This CL optimizes open-coded defers in two ways:
1. It modifies local variable sorting to place all open-coded defer
closure slots in order, so that rather than requiring the metadata to
contain each offset individually, we just need a single offset to the
first slot.
2. Because the slots are in ascending order and can be directly
indexed, we can get rid of the count of how many defers are in the
frame. Instead, we just find the top set bit in the active defers
bitmask, and load the corresponding closure.
Change-Id: I6f912295a492211023a9efe12c94a14f449d86ad
Reviewed-on: https://go-review.googlesource.com/c/go/+/516199
Reviewed-by: Keith Randall <khr@golang.org>
Reviewed-by: Keith Randall <khr@google.com>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
These fields are no longer needed since go.dev/cl/513837.
Change-Id: I980fc9db998c293e930094bbb87e8c8f1654e39c
Reviewed-on: https://go-review.googlesource.com/c/go/+/516198
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Cuong Manh Le <cuong.manhle.vn@gmail.com>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@golang.org>
This CL refactors gopanic, Goexit, and deferreturn to share a common
state machine for processing pending defers. The new state machine
removes a lot of redundant code and does overall less work.
It should also make it easier to implement further optimizations
(e.g., TODOs added in this CL).
Change-Id: I71d3cc8878a6f951d8633505424a191536c8e6b3
Reviewed-on: https://go-review.googlesource.com/c/go/+/513837
Reviewed-by: Keith Randall <khr@golang.org>
Run-TryBot: Matthew Dempsky <mdempsky@google.com>
Reviewed-by: Keith Randall <khr@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This change adds traceBlockReason which leaks fewer implementation
details of the tracer to the runtime. Currently, gopark is called with
an explicit trace event, but this leaks details about trace internals
throughout the runtime.
This change will make it easier to change out the trace implementation.
Change-Id: Id633e1704d2c8838c6abd1214d9695537c4ac7db
Reviewed-on: https://go-review.googlesource.com/c/go/+/494185
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
This reapplies CL 485500, with a fix drafted in CL 492987 incorporated.
CL 485500 is reverted due to #60004 and #60007. #60004 is fixed in
CL 492743. #60007 is fixed in CL 492987 (incorporated in this CL).
[Original CL 485500 description]
This reapplies CL 481061, with the followup fixes in CL 482975, CL 485315, and
CL 485316 incorporated.
CL 481061, by doujiang24 <doujiang24@gmail.com>, speed up C to Go
calls by binding the M to the C thread. See below for its
description.
CL 482975 is a followup fix to a C declaration in testprogcgo.
CL 485315 is a followup fix for x_cgo_getstackbound on Illumos.
CL 485316 is a followup cleanup for ppc64 assembly.
CL 479915 passed the G to _cgo_getstackbound for direct updates to
gp.stack.lo. A G can be reused on a new thread after the previous thread
exited. This could trigger the C TSAN race detector because it couldn't
see the synchronization in Go (lockextra) preventing the same G from
being used on multiple threads at the same time.
We work around this by passing the address of a stack variable to
_cgo_getstackbound rather than the G. The stack is generally unique per
thread, so TSAN won't see the same address from multiple threads. Even
if stacks are reused across threads by pthread, C TSAN should see the
synchonization in the stack allocator.
A regression test is added to misc/cgo/testsanitizer.
[Original CL 481061 description]
This reapplies CL 392854, with the followup fixes in CL 479255,
CL 479915, and CL 481057 incorporated.
CL 392854, by doujiang24 <doujiang24@gmail.com>, speed up C to Go
calls by binding the M to the C thread. See below for its
description.
CL 479255 is a followup fix for a small bug in ARM assembly code.
CL 479915 is another followup fix to address C to Go calls after
the C code uses some stack, but that CL is also buggy.
CL 481057, by Michael Knyszek, is a followup fix for a memory leak
bug of CL 479915.
[Original CL 392854 description]
In a C thread, it's necessary to acquire an extra M by using needm while invoking a Go function from C. But, needm and dropm are heavy costs due to the signal-related syscalls.
So, we change to not dropm while returning back to C, which means binding the extra M to the C thread until it exits, to avoid needm and dropm on each C to Go call.
Instead, we only dropm while the C thread exits, so the extra M won't leak.
When invoking a Go function from C:
Allocate a pthread variable using pthread_key_create, only once per shared object, and register a thread-exit-time destructor.
And store the g0 of the current m into the thread-specified value of the pthread key, only once per C thread, so that the destructor will put the extra M back onto the extra M list while the C thread exits.
When returning back to C:
Skip dropm in cgocallback, when the pthread variable has been created, so that the extra M will be reused the next time invoke a Go function from C.
This is purely a performance optimization. The old version, in which needm & dropm happen on each cgo call, is still correct too, and we have to keep the old version on systems with cgo but without pthreads, like Windows.
This optimization is significant, and the specific value depends on the OS system and CPU, but in general, it can be considered as 10x faster, for a simple Go function call from a C thread.
For the newly added BenchmarkCGoInCThread, some benchmark results:
1. it's 28x faster, from 3395 ns/op to 121 ns/op, in darwin OS & Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
2. it's 6.5x faster, from 1495 ns/op to 230 ns/op, in Linux OS & Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz
[CL 479915 description]
Currently, when C calls into Go the first time, we grab an M
using needm, which sets m.g0's stack bounds using the SP. We don't
know how big the stack is, so we simply assume 32K. Previously,
when the Go function returns to C, we drop the M, and the next
time C calls into Go, we put a new stack bound on the g0 based on
the current SP. After CL 392854, we don't drop the M, and the next
time C calls into Go, we reuse the same g0, without recomputing
the stack bounds. If the C code uses quite a bit of stack space
before calling into Go, the SP may be well below the 32K stack
bound we assumed, so the runtime thinks the g0 stack overflows.
This CL makes needm get a more accurate stack bound from
pthread. (In some platforms this may still be a guess as we don't
know exactly where we are in the C stack), but it is probably
better than simply assuming 32K.
[CL 492987 description]
On the first call into Go from a C thread, currently we set the g0
stack's high bound imprecisely based on the SP. With CL 485500, we
keep the M and don't recompute the stack bounds when it calls into
Go again. If the first call is made when the C thread uses some
deep stack, but a subsequent call is made with a shallower stack,
the SP may be above g0.stack.hi.
This is usually okay as we don't check usually stack.hi. One place
where we do check for stack.hi is in the signal handler, in
adjustSignalStack. In particular, C TSAN delivers signals on the
g0 stack (instead of the usual signal stack). If the SP is above
g0.stack.hi, we don't see it is on the g0 stack, and throws.
This CL makes it get an accurate stack upper bound with the
pthread API (on the platforms where it is available).
Also add some debug print for the "handler not on signal stack"
throw.
Fixes#51676.
Fixes#59294.
Fixes#59678.
Fixes#60007.
Change-Id: Ie51c8e81ade34ec81d69fd7bce1fe0039a470776
Reviewed-on: https://go-review.googlesource.com/c/go/+/495855
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
More tightening up of the tracer's interface.
Change-Id: I992141c7f30e5c2d5d77d1fcd6817d35bc6e5f6d
Reviewed-on: https://go-review.googlesource.com/c/go/+/494191
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
More tightening up of the tracer's interface.
While we're here, clarify why waittraceskip isn't included by explaining
what the wait* fields in the M are really for.
Change-Id: I0e7b4cac79fb77a7a0b3ca6b6cc267668e3610bc
Reviewed-on: https://go-review.googlesource.com/c/go/+/494190
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
More tightening up of the tracer's interface.
This increases the size of each G very slightly, which isn't great, but
we stay within the same size class, so actually memory use will be
unchanged.
Change-Id: I7d1f5798edcf437c212beb1e1a2619eab833aafb
Reviewed-on: https://go-review.googlesource.com/c/go/+/494188
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
Fix comments, including duplicate is, wrong phrases and articles, misspellings, etc.
Change-Id: I8bfea53b9b275e649757cc4bee6a8a026ed9c7a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/493035
Reviewed-by: Benny Siegert <bsiegert@gmail.com>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: shuang cui <imcusg@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Ian Lance Taylor <iant@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
This reverts CL 485500.
Reason for revert: This breaks internal tests at Google, see b/280861579 and b/280820455.
Change-Id: I426278d400f7611170918fc07c524cb059b9cc55
Reviewed-on: https://go-review.googlesource.com/c/go/+/492995
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Chressie Himpel <chressie@google.com>
This reapplies CL 481061, with the followup fixes in CL 482975, CL 485315, and
CL 485316 incorporated.
CL 481061, by doujiang24 <doujiang24@gmail.com>, speed up C to Go
calls by binding the M to the C thread. See below for its
description.
CL 482975 is a followup fix to a C declaration in testprogcgo.
CL 485315 is a followup fix for x_cgo_getstackbound on Illumos.
CL 485316 is a followup cleanup for ppc64 assembly.
[Original CL 481061 description]
This reapplies CL 392854, with the followup fixes in CL 479255,
CL 479915, and CL 481057 incorporated.
CL 392854, by doujiang24 <doujiang24@gmail.com>, speed up C to Go
calls by binding the M to the C thread. See below for its
description.
CL 479255 is a followup fix for a small bug in ARM assembly code.
CL 479915 is another followup fix to address C to Go calls after
the C code uses some stack, but that CL is also buggy.
CL 481057, by Michael Knyszek, is a followup fix for a memory leak
bug of CL 479915.
[Original CL 392854 description]
In a C thread, it's necessary to acquire an extra M by using needm while invoking a Go function from C. But, needm and dropm are heavy costs due to the signal-related syscalls.
So, we change to not dropm while returning back to C, which means binding the extra M to the C thread until it exits, to avoid needm and dropm on each C to Go call.
Instead, we only dropm while the C thread exits, so the extra M won't leak.
When invoking a Go function from C:
Allocate a pthread variable using pthread_key_create, only once per shared object, and register a thread-exit-time destructor.
And store the g0 of the current m into the thread-specified value of the pthread key, only once per C thread, so that the destructor will put the extra M back onto the extra M list while the C thread exits.
When returning back to C:
Skip dropm in cgocallback, when the pthread variable has been created, so that the extra M will be reused the next time invoke a Go function from C.
This is purely a performance optimization. The old version, in which needm & dropm happen on each cgo call, is still correct too, and we have to keep the old version on systems with cgo but without pthreads, like Windows.
This optimization is significant, and the specific value depends on the OS system and CPU, but in general, it can be considered as 10x faster, for a simple Go function call from a C thread.
For the newly added BenchmarkCGoInCThread, some benchmark results:
1. it's 28x faster, from 3395 ns/op to 121 ns/op, in darwin OS & Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
2. it's 6.5x faster, from 1495 ns/op to 230 ns/op, in Linux OS & Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz
[CL 479915 description]
Currently, when C calls into Go the first time, we grab an M
using needm, which sets m.g0's stack bounds using the SP. We don't
know how big the stack is, so we simply assume 32K. Previously,
when the Go function returns to C, we drop the M, and the next
time C calls into Go, we put a new stack bound on the g0 based on
the current SP. After CL 392854, we don't drop the M, and the next
time C calls into Go, we reuse the same g0, without recomputing
the stack bounds. If the C code uses quite a bit of stack space
before calling into Go, the SP may be well below the 32K stack
bound we assumed, so the runtime thinks the g0 stack overflows.
This CL makes needm get a more accurate stack bound from
pthread. (In some platforms this may still be a guess as we don't
know exactly where we are in the C stack), but it is probably
better than simply assuming 32K.
[CL 485500 description]
CL 479915 passed the G to _cgo_getstackbound for direct updates to
gp.stack.lo. A G can be reused on a new thread after the previous thread
exited. This could trigger the C TSAN race detector because it couldn't
see the synchronization in Go (lockextra) preventing the same G from
being used on multiple threads at the same time.
We work around this by passing the address of a stack variable to
_cgo_getstackbound rather than the G. The stack is generally unique per
thread, so TSAN won't see the same address from multiple threads. Even
if stacks are reused across threads by pthread, C TSAN should see the
synchonization in the stack allocator.
A regression test is added to misc/cgo/testsanitizer.
Fixes#51676.
Fixes#59294.
Fixes#59678.
Change-Id: Ic62be31a06ee83568215e875a891df37084e08ca
Reviewed-on: https://go-review.googlesource.com/c/go/+/485500
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Cherry Mui <cherryyz@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
This reverts CL 481061.
Reason for revert: When built with C TSAN, x_cgo_getstackbound triggers
race detection on `g->stacklo` because the synchronization is in Go,
which isn't instrumented.
For #51676.
For #59294.
For #59678.
Change-Id: I38afcda9fcffd6537582a39a5214bc23dc147d47
Reviewed-on: https://go-review.googlesource.com/c/go/+/485275
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Than McIntosh <thanm@google.com>
This reapplies CL 392854, with the followup fixes in CL 479255,
CL 479915, and CL 481057 incorporated.
CL 392854, by doujiang24 <doujiang24@gmail.com>, speed up C to Go
calls by binding the M to the C thread. See below for its
description.
CL 479255 is a followup fix for a small bug in ARM assembly code.
CL 479915 is another followup fix to address C to Go calls after
the C code uses some stack, but that CL is also buggy.
CL 481057, by Michael Knyszek, is a followup fix for a memory leak
bug of CL 479915.
[Original CL 392854 description]
In a C thread, it's necessary to acquire an extra M by using needm while invoking a Go function from C. But, needm and dropm are heavy costs due to the signal-related syscalls.
So, we change to not dropm while returning back to C, which means binding the extra M to the C thread until it exits, to avoid needm and dropm on each C to Go call.
Instead, we only dropm while the C thread exits, so the extra M won't leak.
When invoking a Go function from C:
Allocate a pthread variable using pthread_key_create, only once per shared object, and register a thread-exit-time destructor.
And store the g0 of the current m into the thread-specified value of the pthread key, only once per C thread, so that the destructor will put the extra M back onto the extra M list while the C thread exits.
When returning back to C:
Skip dropm in cgocallback, when the pthread variable has been created, so that the extra M will be reused the next time invoke a Go function from C.
This is purely a performance optimization. The old version, in which needm & dropm happen on each cgo call, is still correct too, and we have to keep the old version on systems with cgo but without pthreads, like Windows.
This optimization is significant, and the specific value depends on the OS system and CPU, but in general, it can be considered as 10x faster, for a simple Go function call from a C thread.
For the newly added BenchmarkCGoInCThread, some benchmark results:
1. it's 28x faster, from 3395 ns/op to 121 ns/op, in darwin OS & Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
2. it's 6.5x faster, from 1495 ns/op to 230 ns/op, in Linux OS & Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz
[CL 479915 description]
Currently, when C calls into Go the first time, we grab an M
using needm, which sets m.g0's stack bounds using the SP. We don't
know how big the stack is, so we simply assume 32K. Previously,
when the Go function returns to C, we drop the M, and the next
time C calls into Go, we put a new stack bound on the g0 based on
the current SP. After CL 392854, we don't drop the M, and the next
time C calls into Go, we reuse the same g0, without recomputing
the stack bounds. If the C code uses quite a bit of stack space
before calling into Go, the SP may be well below the 32K stack
bound we assumed, so the runtime thinks the g0 stack overflows.
This CL makes needm get a more accurate stack bound from
pthread. (In some platforms this may still be a guess as we don't
know exactly where we are in the C stack), but it is probably
better than simply assuming 32K.
Fixes#51676.
Fixes#59294.
Change-Id: I9bf1400106d5c08ce621d2ed1df3a2d9e3f55494
Reviewed-on: https://go-review.googlesource.com/c/go/+/481061
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
Reviewed-by: DeJiang Zhu (doujiang) <doujiang24@gmail.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
This reverts CL 392854.
Reason for revert: caused #59294, which was derived from google
internal tests. The attempted fix of #59294 caused more breakage.
Change-Id: I5a061561ac2740856b7ecc09725ac28bd30f8bba
Reviewed-on: https://go-review.googlesource.com/c/go/+/481060
Reviewed-by: Heschi Kreinick <heschi@google.com>
Run-TryBot: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
In a C thread, it's necessary to acquire an extra M by using needm while invoking a Go function from C. But, needm and dropm are heavy costs due to the signal-related syscalls.
So, we change to not dropm while returning back to C, which means binding the extra M to the C thread until it exits, to avoid needm and dropm on each C to Go call.
Instead, we only dropm while the C thread exits, so the extra M won't leak.
When invoking a Go function from C:
Allocate a pthread variable using pthread_key_create, only once per shared object, and register a thread-exit-time destructor.
And store the g0 of the current m into the thread-specified value of the pthread key, only once per C thread, so that the destructor will put the extra M back onto the extra M list while the C thread exits.
When returning back to C:
Skip dropm in cgocallback, when the pthread variable has been created, so that the extra M will be reused the next time invoke a Go function from C.
This is purely a performance optimization. The old version, in which needm & dropm happen on each cgo call, is still correct too, and we have to keep the old version on systems with cgo but without pthreads, like Windows.
This optimization is significant, and the specific value depends on the OS system and CPU, but in general, it can be considered as 10x faster, for a simple Go function call from a C thread.
For the newly added BenchmarkCGoInCThread, some benchmark results:
1. it's 28x faster, from 3395 ns/op to 121 ns/op, in darwin OS & Intel(R) Core(TM) i7-9750H CPU @ 2.60GHz
2. it's 6.5x faster, from 1495 ns/op to 230 ns/op, in Linux OS & Intel(R) Xeon(R) CPU E5-2630 0 @ 2.30GHz
Fixes#51676
Change-Id: I380702fe2f9b6b401b2d6f04b0aba990f4b9ee6c
GitHub-Last-Rev: 93dc64ad98
GitHub-Pull-Request: golang/go#51679
Reviewed-on: https://go-review.googlesource.com/c/go/+/392854
Reviewed-by: Ian Lance Taylor <iant@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: thepudds <thepudds1460@gmail.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
This is relatively easy using the new traceback iterator.
Ancestor tracebacks are now limited to 50 frames. We could keep that
at 100, but the fact that it used 100 before seemed arbitrary and
unnecessary.
Fixes#7181
Updates #54466
Change-Id: If693045881d84848f17e568df275a5105b6f1cb0
Reviewed-on: https://go-review.googlesource.com/c/go/+/475960
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Michael Pratt <mpratt@google.com>
Printing is the only remaining functionality of gentraceback. Move
this into the traceback printing code and eliminate gentraceback. This
lets us simplify the logic, which fixes at least one minor bug:
previously, if inline unwinding pushed the total printed count over
_TracebackMaxFrames, we would print extra frames and then fail to
print "additional frames elided".
The cumulative performance effect of the series of changes starting
with "add a benchmark of Callers" (CL 472956) is:
goos: linux
goarch: amd64
pkg: runtime
cpu: Intel(R) Xeon(R) CPU E5-2690 v3 @ 2.60GHz
│ baseline │ unwinder │
│ sec/op │ sec/op vs base │
Callers/cached-48 1.464µ ± 1% 1.684µ ± 1% +15.03% (p=0.000 n=20)
Callers/inlined-48 1.391µ ± 1% 1.536µ ± 1% +10.42% (p=0.000 n=20)
Callers/no-cache-48 10.50µ ± 1% 11.11µ ± 0% +5.82% (p=0.000 n=20)
StackCopyPtr-48 88.74m ± 1% 81.22m ± 2% -8.48% (p=0.000 n=20)
StackCopy-48 80.90m ± 1% 70.56m ± 1% -12.78% (p=0.000 n=20)
StackCopyNoCache-48 2.458m ± 1% 2.209m ± 1% -10.15% (p=0.000 n=20)
StackCopyWithStkobj-48 26.81m ± 1% 25.66m ± 1% -4.28% (p=0.000 n=20)
geomean 518.8µ 512.9µ -1.14%
The performance impact of intermediate CLs in this sequence varies a
lot as we went through many refactorings. The slowdown in Callers
comes primarily from the introduction of unwinder because that doesn't
get inlined and results in somewhat worse code generation in code
that's extremely hot in those microbenchmarks. The performance gains
on stack copying come mostly from replacing callbacks with direct use
of the unwinder.
Updates #54466.
Fixes#32383.
Change-Id: I4970603b2861633eecec30545e852688bc7cc9a4
Reviewed-on: https://go-review.googlesource.com/c/go/+/468301
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Austin Clements <austin@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Currently, all stack walking logic is in one venerable, large, and
very, very complicated function: runtime.gentraceback. This function
has three distinct operating modes: printing, populating a PC buffer,
or invoking a callback. And it has three different modes of unwinding:
physical Go frames, inlined Go frames, and cgo frames. It also has
several flags. All of this logic is very interwoven.
This CL reimplements the monolithic gentraceback function as an
"unwinder" type with an iterator API. It moves all of the logic for
stack walking into this new type, and gentraceback is now a
much-simplified wrapper around the new unwinder type that still
implements printing, populating a PC buffer, and invoking a callback.
Follow-up CLs will replace uses of gentraceback with direct uses of
unwinder.
Exposing traceback functionality as an iterator API will enable a lot
of follow-up work such as simplifying the open-coded defer
implementation (which should in turn help with #26813 and #37233),
printing the bottom of deep stacks (#7181), and eliminating the small
limit on CPU stacks in profiles (#56029).
Fixes#54466.
Change-Id: I36e046dc423c9429c4f286d47162af61aff49a0d
Reviewed-on: https://go-review.googlesource.com/c/go/+/458218
Reviewed-by: Michael Pratt <mpratt@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Run-TryBot: Austin Clements <austin@google.com>
We've replicated the code to expand inlined frames in many places in
the runtime at this point. This CL adds a simple iterator API that
abstracts this out.
We also use this to try out a new idea for structuring tests of
runtime internals: rather than exporting this whole internal data type
and API, we write the test in package runtime and import the few bits
of std we need. The idea is that, for tests of internals, it's easier
to inject public APIs from std than it is to export non-public APIs
from runtime. This is discussed more in #55108.
For #54466.
Change-Id: Iebccc04ff59a1509694a8ac0e0d3984e49121339
Reviewed-on: https://go-review.googlesource.com/c/go/+/466096
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This change adds a new GODEBUG flag called pagetrace that writes a
low-overhead trace of how pages of memory are managed by the Go runtime.
The page tracer is kept behind a GOEXPERIMENT flag due to a potential
security risk for setuid binaries.
Change-Id: I6f4a2447d02693c25214400846a5d2832ad6e5c0
Reviewed-on: https://go-review.googlesource.com/c/go/+/444157
Reviewed-by: Austin Clements <austin@google.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
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Ms are allocated via standard heap allocation (`new(m)`), which means we
must keep them alive (i.e., reachable by the GC) until we are completely
done using them.
Ms are primarily reachable through runtime.allm. However, runtime.mexit
drops the M from allm fairly early, long before it is done using the M
structure. If that was the last reference to the M, it is now at risk of
being freed by the GC and used for some other allocation, leading to
memory corruption.
Ms with a Go-allocated stack coincidentally already keep a reference to
the M in sched.freem, so that the stack can be freed lazily. This
reference has the side effect of keeping this Ms reachable. However, Ms
with an OS stack skip this and are at risk of corruption.
Fix this lifetime by extending sched.freem use to all Ms, with the value
of mp.freeWait determining whether the stack needs to be freed or not.
Fixes#56243.
Change-Id: Ic0c01684775f5646970df507111c9abaac0ba52e
Reviewed-on: https://go-review.googlesource.com/c/go/+/443716
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Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Knyszek <mknyszek@google.com>
This adds the function "start line number" to runtime._func and
runtime.inlinedCall objects. The "start line number" is the line number
of the func keyword or TEXT directive for assembly.
Subtracting the start line number from PC line number provides the
relative line offset of a PC from the the start of the function. This
helps with source stability by allowing code above the function to move
without invalidating samples within the function.
Encoding start line rather than relative lines directly is convenient
because the pprof format already contains a start line field.
This CL uses a straightforward encoding of explictly including a start
line field in every _func and inlinedCall. It is possible that we could
compress this further in the future. e.g., functions with a prologue
usually have <line of PC 0> == <start line>. In runtime.test, 95% of
functions have <line of PC 0> == <start line>.
According to bent, this is geomean +0.83% binary size vs master and
-0.31% binary size vs 1.19.
Note that //line directives can change the file and line numbers
arbitrarily. The encoded start line is as adjusted by //line directives.
Since this can change in the middle of a function, `line - start line`
offset calculations may not be meaningful if //line directives are in
use.
For #55022.
Change-Id: Iaabbc6dd4f85ffdda294266ef982ae838cc692f6
Reviewed-on: https://go-review.googlesource.com/c/go/+/429638
Run-TryBot: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
Reviewed-by: Matthew Dempsky <mdempsky@google.com>
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Reviewed-by: Cherry Mui <cherryyz@google.com>
Extra Ms may lead to the "no consistent ordering of events possible" error when parsing trace file with cgo enabled, since:
1. The gs in the extra Ms may be in `_Gdead` status while starting trace by invoking `runtime.StartTrace`,
2. and these gs will trigger `traceEvGoSysExit` events in `runtime.exitsyscall` when invoking go functions from c,
3. then, the events of those gs are under non-consistent ordering, due to missing the previous events.
Add two events, `traceEvGoCreate` and `traceEvGoInSyscall`, in `runtime.StartTrace`, will make the trace parser happy.
Fixes#29707
Change-Id: I2fd9d1713cda22f0ddb36efe1ab351f88da10881
GitHub-Last-Rev: 7bbfddb81b
GitHub-Pull-Request: golang/go#54974
Reviewed-on: https://go-review.googlesource.com/c/go/+/429858
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Bryan Mills <bcmills@google.com>
Run-TryBot: xie cui <523516579@qq.com>
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Auto-Submit: Michael Pratt <mpratt@google.com>
This change adds a metric to the runtime/metrics package which tracks
total mutex wait time for sync.Mutex and sync.RWMutex. The purpose of
this metric is to be able to quickly get an idea of the total mutex wait
time.
The implementation of this metric piggybacks off of the existing G
runnable tracking infrastructure, as well as the wait reason set on a G
when it goes into _Gwaiting.
Fixes#49881.
Change-Id: I4691abf64ac3574bec69b4d7d4428b1573130517
Reviewed-on: https://go-review.googlesource.com/c/go/+/427618
Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
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Currently, wait reasons are set somewhat inconsistently. In a follow-up
CL, we're going to want to rely on the wait reason being there for
casgstatus, so the status quo isn't really going to work for that. Plus
this inconsistency means there are a whole bunch of cases where we could
be more specific about the G's status but aren't.
So, this change adds a new function, casGToWaiting which is like
casgstatus but also sets the wait reason. The goal is that by using this
API it'll be harder to forget to set a wait reason (or the lack thereof
will at least be explicit). This change then updates all casgstatus(gp,
..., _Gwaiting) calls to casGToWaiting(gp, ..., waitReasonX) instead.
For a number of these cases, we're missing a wait reason, and it
wouldn't hurt to add a wait reason for them, so this change also adds
those wait reasons.
For #49881.
Change-Id: Ia95e06ecb74ed17bb7bb94f1a362ebfe6bec1518
Reviewed-on: https://go-review.googlesource.com/c/go/+/427617
Reviewed-by: Michael Pratt <mpratt@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
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This change adds 3 new waitReasons that correspond to sync.Mutex.Lock,
sync.RWMutex.RLock, and sync.RWMutex.Lock that are plumbed down into
semacquire1 by exporting new functions to the sync package from the
runtime.
Currently these three functions show up as "semacquire" in backtraces
which isn't very clear, though the stack trace itself should reveal
what's really going on. This represents a minor improvement to backtrace
readability, though blocking on an RWMutex.w.Lock will still show up as
blocking on a regular mutex (I suppose technically it is).
This is a step toward helping the runtime identify when a goroutine is
blocked on a mutex of some kind.
For #49881.
Change-Id: Ia409b4d27e117fe4bfdc25fa541e9c58d6d587b9
Reviewed-on: https://go-review.googlesource.com/c/go/+/427616
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
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Run-TryBot: Michael Knyszek <mknyszek@google.com>
This changes adds a breakdown for estimated CPU usage by time. These
estimates are not based on real on-CPU counters, so each metric has a
disclaimer explaining so. They can, however, be more reasonably
compared to a total CPU time metric that this change also adds.
Fixes#47216.
Change-Id: I125006526be9f8e0d609200e193da5a78d9935be
Reviewed-on: https://go-review.googlesource.com/c/go/+/404307
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Josh MacDonald <jmacd@lightstep.com>
Auto-Submit: Michael Knyszek <mknyszek@google.com>
Reviewed-by: David Chase <drchase@google.com>
Run-TryBot: Michael Knyszek <mknyszek@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
To match _func.nameOff.
Change-Id: I75e71cadaa0f7ca8844d1b49950673797b227074
Reviewed-on: https://go-review.googlesource.com/c/go/+/428658
Run-TryBot: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
TryBot-Result: Gopher Robot <gobot@golang.org>
Auto-Submit: Michael Pratt <mpratt@google.com>
Switch to the more Go-style name to match inlinedCall.nameOff.
Change-Id: I2115b27af8309e1ead7d61ecc65fe4fc966030f7
Reviewed-on: https://go-review.googlesource.com/c/go/+/428657
Run-TryBot: Michael Pratt <mpratt@google.com>
Auto-Submit: Michael Pratt <mpratt@google.com>
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Reviewed-by: Cherry Mui <cherryyz@google.com>
Note that this changes some unsynchronized operations of g.atomicstatus to synchronized operations.
Updates #53821
Change-Id: If249d62420ea09fbec39b570942f96c63669c333
Reviewed-on: https://go-review.googlesource.com/c/go/+/425363
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Reviewed-by: Heschi Kreinick <heschi@google.com>
Currently these are only implicitly documented by the code that
generates and consumes them. Add explicit documentation.
Change-Id: I25a1294f04dc11785242643bec83370c66ff7a20
Reviewed-on: https://go-review.googlesource.com/c/go/+/427954
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The stkframe struct and its methods are strewn across different source
files. Since they actually have a pretty coherent theme at this point,
migrate it all into a new file, stkframe.go. There are no code changes
in this CL.
For #54466, albeit rather indirectly.
Change-Id: Ibe53fc4b1106d131005e1c9d491be838a8f14211
Reviewed-on: https://go-review.googlesource.com/c/go/+/424516
Reviewed-by: Michael Pratt <mpratt@google.com>
Reviewed-by: Cherry Mui <cherryyz@google.com>
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Auto-Submit: Austin Clements <austin@google.com>
Currently, stkframe.arglen and stkframe.argmap are populated by
gentraceback under a particular set of circumstances. But because they
can be constructed from other fields in stkframe, they don't need to
be computed eagerly at all. They're also rather misleading, as they're
only part of computing the actual argument map and most callers should
be using getStackMap, which does the rest of the work.
This CL drops these fields from stkframe. It shifts the functions that
used to compute them, getArgInfoFast and getArgInfo, into
corresponding methods stkframe.argBytes and stkframe.argMapInternal.
argBytes is expected to be used by callers that need to know only the
argument frame size, while argMapInternal is used only by argBytes and
getStackMap.
We also move some of the logic from getStackMap into argMapInternal
because the previous split of responsibilities didn't make much sense.
This lets us return just a bitvector from argMapInternal, rather than
both a bitvector, which carries a size, and an "actually use this
size".
The getArgInfoFast function was inlined before (and inl_test checked
this). We drop that requirement from stkframe.argBytes because the
uses of this have shifted and now it's only called from heap dumping
(which never happens) and conservative stack frame scanning (which
very, very rarely happens).
There will be a few follow-up clean-up CLs.
For #54466. This is a nice clean-up on its own, but it also serves to
remove pointers from the traceback state that would eventually become
troublesome write barriers once we stack-rip gentraceback.
Change-Id: I107f98ed8e7b00185c081de425bbf24af02a4163
Reviewed-on: https://go-review.googlesource.com/c/go/+/424514
Run-TryBot: Austin Clements <austin@google.com>
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Reviewed-by: Cherry Mui <cherryyz@google.com>
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The meaning of some of the fields in stkframe is actually quite
subtle.
Change-Id: Iac765ff6fbf4c3b7c9f2453f5b4a2e5e640f5750
Reviewed-on: https://go-review.googlesource.com/c/go/+/424256
TryBot-Result: Gopher Robot <gobot@golang.org>
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Reviewed-by: Michael Pratt <mpratt@google.com>
Auto-Submit: Austin Clements <austin@google.com>
Note that this changes the non-atomic operations in p.destroy() to atomic operations.
For #53821
Change-Id: I7bba77c9a2287ba697c87cce2c79293e4d1b3334
Reviewed-on: https://go-review.googlesource.com/c/go/+/425774
Run-TryBot: Michael Knyszek <mknyszek@google.com>
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Note that this changes a few unsynchronized operations of forcegcstate.idle to synchronized operations.
Updates #53821
Change-Id: I041654cc84a188fad45e2df7abce3a434f9a1f15
Reviewed-on: https://go-review.googlesource.com/c/go/+/425361
Reviewed-by: Michael Knyszek <mknyszek@google.com>
Reviewed-by: Michael Pratt <mpratt@google.com>
On the write side, g.selectDone has been converted
from non-atomic to atomic access.
For #53821.
Change-Id: Iac46bc6acce7eed51dfd990285dd57f0d58b4ae2
Reviewed-on: https://go-review.googlesource.com/c/go/+/425414
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CL 424396 and CL 424397 changed timer0When/timerModifiedEarliest to
atomic.Uint64, just they're guaranted to have 64-bit alignment.
Change-Id: Idaff1059da2aac84520b9b0e34f9721a74dbba5a
Reviewed-on: https://go-review.googlesource.com/c/go/+/424794
Auto-Submit: Cuong Manh Le <cuong.manhle.vn@gmail.com>
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So they match with when/nextwhen fields of timer struct.
Updates #53821
Change-Id: Iad0cceb129796745774facfbbfe5756df3a320b4
Reviewed-on: https://go-review.googlesource.com/c/go/+/423117
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