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9 daysruntime: fix timespec definition on 32bits systemsJorropo
The nsec field of timespec is a C long even when using 64bits time on 32bits systems. This is because by timespec API if nsec never holds more than a second worth of nanoseconds. If it would theses would increment the sec field while the nsec field would get the amount of nanoseconds modulus a second. Fixes #77934 Change-Id: I9803998ba70123eb3b226379bd72b11cae972c38 Reviewed-on: https://go-review.googlesource.com/c/go/+/751341 Reviewed-by: Michael Pratt <mpratt@google.com> Auto-Submit: Jorropo <jorropo.pgm@gmail.com> Reviewed-by: David Chase <drchase@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2025-10-30runtime: delete timedivRuss Cox
Now that the compiler handles constant 64-bit divisions without function calls on 32-bit systems, we no longer need to maintain and test a bad custom implementation of 64-bit division. Change-Id: If28807ad4f86507267ae69bc8f0b09ec18e98b66 Reviewed-on: https://go-review.googlesource.com/c/go/+/716463 LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Russ Cox <rsc@golang.org> Reviewed-by: Alan Donovan <adonovan@google.com>
2025-10-21runtime: use timer_settime64 on 32-bit Linuxabdullahkiani007
Linux introduced new syscalls to fix the year 2038 issue. To still be able to use the old ones, the Kconfig option COMPAT_32BIT_TIME would be necessary. Use the new 64-bit syscall for timer_settime by default. Add a fallback to use the 32-bit syscall when the 64-bit version returns _ENOSYS. Fixes #75133 Change-Id: Iccb8831b67f665067ee526e93c3ff2f4f5392edf GitHub-Last-Rev: 6c3d62d60e5ff02ebe61e56e06d6365e530ec39e GitHub-Pull-Request: golang/go#75957 Reviewed-on: https://go-review.googlesource.com/c/go/+/712642 Reviewed-by: Jorropo <jorropo.pgm@gmail.com> Reviewed-by: David Chase <drchase@google.com> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com> Auto-Submit: Jorropo <jorropo.pgm@gmail.com>
2025-09-18runtime: use futexes with 64-bit time on LinuxDaniel Maslowski
Linux introduced new syscalls to fix the year 2038 issue. To still be able to use the old ones, the Kconfig option COMPAT_32BIT_TIME would be necessary. Use the new syscall with 64-bit values for futex by default. Define _ENOSYS for detecting if it's not available. Add a fallback to use the older syscall in case the new one is not available, since Go runs on Linux from 2.6.32 on, per https://go.dev/wiki/MinimumRequirements. Updates #75133 Change-Id: I65daff0a3d06b55440ff05d8f5a9aa1c07eb201d GitHub-Last-Rev: 96dd1bd84bd12d898e971157fc83da562cc4f6b4 GitHub-Pull-Request: golang/go#75306 Reviewed-on: https://go-review.googlesource.com/c/go/+/701615 Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Mark Freeman <markfreeman@google.com> Reviewed-by: Jorropo <jorropo.pgm@gmail.com> LUCI-TryBot-Result: Go LUCI <golang-scoped@luci-project-accounts.iam.gserviceaccount.com>
2023-08-22runtime: avoid MADV_HUGEPAGE for heap memoryMichael Anthony Knyszek
Currently the runtime marks all new memory as MADV_HUGEPAGE on Linux and manages its hugepage eligibility status. Unfortunately, the default THP behavior on most Linux distros is that MADV_HUGEPAGE blocks while the kernel eagerly reclaims and compacts memory to allocate a hugepage. This direct reclaim and compaction is unbounded, and may result in significant application thread stalls. In really bad cases, this can exceed 100s of ms or even seconds. Really all we want is to undo MADV_NOHUGEPAGE marks and let the default Linux paging behavior take over, but the only way to unmark a region as MADV_NOHUGEPAGE is to also mark it MADV_HUGEPAGE. The overall strategy of trying to keep hugepages for the heap unbroken however is sound. So instead let's use the new shiny MADV_COLLAPSE if it exists. MADV_COLLAPSE makes a best-effort synchronous attempt at collapsing the physical memory backing a memory region into a hugepage. We'll use MADV_COLLAPSE where we would've used MADV_HUGEPAGE, and stop using MADV_NOHUGEPAGE altogether. Because MADV_COLLAPSE is synchronous, it's also important to not re-collapse huge pages if the huge pages are likely part of some large allocation. Although in many cases it's advantageous to back these allocations with hugepages because they're contiguous, eagerly collapsing every hugepage means having to page in at least part of the large allocation. However, because we won't use MADV_NOHUGEPAGE anymore, we'll no longer handle the fact that khugepaged might come in and back some memory we returned to the OS with a hugepage. I've come to the conclusion that this is basically unavoidable without a new madvise flag and that it's just not a good default. If this change lands, advice about Linux huge page settings will be added to the GC guide. Verified that this change doesn't regress Sweet, at least not on my machine with: /sys/kernel/mm/transparent_hugepage/enabled [always or madvise] /sys/kernel/mm/transparent_hugepage/defrag [madvise] /sys/kernel/mm/transparent_hugepage/khugepaged/max_ptes_none [0 or 511] Unfortunately, this workaround means that we only get forced hugepages on Linux 6.1+. Fixes #61718. Change-Id: I7f4a7ba397847de29f800a99f9cb66cb2720a533 Reviewed-on: https://go-review.googlesource.com/c/go/+/516795 Reviewed-by: Austin Clements <austin@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Michael Knyszek <mknyszek@google.com> Auto-Submit: Michael Knyszek <mknyszek@google.com>
2022-11-18runtime: add page tracerMichael Knyszek
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> TryBot-Result: Gopher Robot <gobot@golang.org>
2022-10-07runtime: move epoll syscalls to runtime/internal/syscallAndrew Pogrebnoy
This change moves Linux epoll's syscalls implementation to the "runtime/internal/syscall" package. The intention in this CL was to minimise behavioural changes but make the code more generalised. This also will allow adding new syscalls (like epoll_pwait2) without the need to implement assembly stubs for each arch. It also drops epoll_create as not all architectures provide this call. epoll_create1 was added to the kernel in version 2.6.27 and Go requires Linux kernel version 2.6.32 or later since Go 1.18. So it is safe to always use epoll_create1. This is a resubmit as the previous CL 421994 was reverted due to test failures after the merge with the master. The issue was fixed in CL 438615 For #53824 For #51087 Change-Id: I1bd0f23a85b4f9b80178c5dd36fd3e95ff4f9648 Reviewed-on: https://go-review.googlesource.com/c/go/+/440115 Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Auto-Submit: Michael Pratt <mpratt@google.com> Reviewed-by: Michael Pratt <mpratt@google.com> Run-TryBot: Michael Pratt <mpratt@google.com>
2022-09-30Revert "runtime: move epoll syscalls to runtime/internal/syscall"Michael Pratt
This reverts CL 421994. Reason for revert: breaks runtime.TestCheckPtr2 For #53824 For #51087 Change-Id: I044ea4d6efdffe0a4b7fb0d2bb3717d9f391fc59 Reviewed-on: https://go-review.googlesource.com/c/go/+/437295 TryBot-Result: Gopher Robot <gobot@golang.org> Run-TryBot: Michael Pratt <mpratt@google.com> Auto-Submit: Michael Pratt <mpratt@google.com> Reviewed-by: Bryan Mills <bcmills@google.com>
2022-09-30runtime: move epoll syscalls to runtime/internal/syscallAndrew Pogrebnoy
This change moves Linux epoll's syscalls implementation to the "runtime/internal/syscall" package. The intention in this CL was to minimise behavioural changes but make the code more generalised. This also will allow adding new syscalls (like epoll_pwait2) without the need to implement assembly stubs for each arch. It also drops epoll_create as not all architectures provide this call. epoll_create1 was added to the kernel in version 2.6.27 and Go requires Linux kernel version 2.6.32 or later since Go 1.18. So it is safe to always use epoll_create1. For #53824 For #51087 Change-Id: I9a6a26b7f2075a38e041de1bab4691da0ecb94fc Reviewed-on: https://go-review.googlesource.com/c/go/+/421994 Reviewed-by: Michael Pratt <mpratt@google.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Dmitri Shuralyov <dmitshur@google.com> Run-TryBot: Michael Pratt <mpratt@google.com> Auto-Submit: Michael Pratt <mpratt@google.com>
2022-03-03runtime: remove fallback to pipe on platforms with pipe2Tobias Klauser
On Linux, the minimum required kernel version for Go 1.18 was be changed to 2.6.32, see #45964. The pipe2 syscall was added in 2.6.27. All other platforms already provide the pipe2 syscall in the minimum supported version: - DragonFly BSD added it in version 4.2, see https://www.dragonflybsd.org/release42/ - FreeBSD added it in version 10.0, see https://www.freebsd.org/cgi/man.cgi?pipe(2)#end - NetBSD added it in version 6.0, see https://man.netbsd.org/pipe2.2#HISTORY - OpenBSD added it in version 5.7, see https://man.openbsd.org/pipe.2#HISTORY - Illumos supports it since 2013, see https://www.illumos.org/issues/3714 - Solaris supports it since 11.4 This also allows to remove setNonblock which was only used in the pipe fallback path on these platforms. Change-Id: I1f40d32fd3065d74e22af77b9ff2292b9cf66706 Reviewed-on: https://go-review.googlesource.com/c/go/+/389354 Trust: Tobias Klauser <tobias.klauser@gmail.com> Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> TryBot-Result: Gopher Robot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2022-02-15runtime, syscall: reimplement AllThreadsSyscall using only signals.Michael Pratt
In issue 50113, we see that a thread blocked in a system call can result in a hang of AllThreadsSyscall. To resolve this, we must send a signal to these threads to knock them out of the system call long enough to run the per-thread syscall. Stepping back, if we need to send signals anyway, it should be possible to implement this entire mechanism on top of signals. This CL does so, vastly simplifying the mechanism, both as a direct result of newly-unnecessary code as well as some ancillary simplifications to make things simpler to follow. Major changes: * The rest of the mechanism is moved to os_linux.go, with fields in mOS instead of m itself. * 'Fixup' fields and functions are renamed to 'perThreadSyscall' so they are more precise about their purpose. * Rather than getting passed a closure, doAllThreadsSyscall takes the syscall number and arguments. This avoids a lot of hairy behavior: * The closure may potentially only be live in fields in the M, hidden from the GC. Not necessary with no closure. * The need to loan out the race context. A direct RawSyscall6 call does not require any race context. * The closure previously conditionally panicked in strange locations, like a signal handler. Now we simply throw. * All manual fixup synchronization with mPark, sysmon, templateThread, sigqueue, etc is gone. The core approach is much simpler: doAllThreadsSyscall sends a signal to every thread in allm, which executes the system call from the signal handler. We use (SIGRTMIN + 1), aka SIGSETXID, the same signal used by glibc for this purpose. As such, we are careful to only handle this signal on non-cgo binaries. Synchronization with thread creation is a key part of this CL. The comment near the top of doAllThreadsSyscall describes the required synchronization semantics and how they are achieved. Note that current use of allocmLock protects the state mutations of allm that are also protected by sched.lock. allocmLock is used instead of sched.lock simply to avoid holding sched.lock for so long. Fixes #50113 Change-Id: Ic7ea856dc66cf711731540a54996e08fc986ce84 Reviewed-on: https://go-review.googlesource.com/c/go/+/383434 Reviewed-by: Austin Clements <austin@google.com> Trust: Michael Pratt <mpratt@google.com> Run-TryBot: Michael Pratt <mpratt@google.com> TryBot-Result: Gopher Robot <gobot@golang.org>
2021-11-02runtime: add padding to Linux kernel structuresRhys Hiltner
Go exchanges siginfo and sigevent structures with the kernel. They contain unions, but Go's use is limited to the first few fields. Pad out the rest so the size Go sees is the same as what the Linux kernel sees. This is a follow-up to CL 342052 which added the sigevent struct without padding, and to CL 353136 which added the padding but with an assertion that confused several type-checkers. It updates the siginfo struct as well so there are no bad examples in the defs_linux_*.go files. Reviewed-on: https://go-review.googlesource.com/c/go/+/353136 Change-Id: I9610632ff0ec43eba91f560536f5441fa907b36f Reviewed-on: https://go-review.googlesource.com/c/go/+/360094 Run-TryBot: Ian Lance Taylor <iant@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org> Reviewed-by: Michael Pratt <mpratt@google.com>
2021-10-04Revert "runtime: add padding to Linux kernel structures"Michael Pratt
This reverts commit f0db7eae74ea235e9fbc2598252bfd46c1cc5510. Reason for revert: Breaks linux-386 tests Change-Id: Ia51fbf97460ab52920b67d6db6177ac2d6b0058e Reviewed-on: https://go-review.googlesource.com/c/go/+/353432 Trust: Michael Pratt <mpratt@google.com> Run-TryBot: Michael Pratt <mpratt@google.com> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Bryan C. Mills <bcmills@google.com>
2021-10-04runtime: add padding to Linux kernel structuresRhys Hiltner
Go exchanges siginfo and sigevent structures with the kernel. They contain unions, but Go's use is limited to the first few fields. Pad out the rest so the size Go sees is the same as what the Linux kernel sees. This is a follow-up to CL 342052 which added the sigevent struct without padding. It updates the siginfo struct as well so there are no bad examples in the defs_linux_*.go files. Change-Id: Id991d4a57826677dd7e6cc30ad113fa3b321cddf Reviewed-on: https://go-review.googlesource.com/c/go/+/353136 Run-TryBot: Rhys Hiltner <rhys@justin.tv> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Michael Pratt <mpratt@google.com> Trust: Michael Knyszek <mknyszek@google.com>
2021-09-27runtime: add timer_create syscalls for LinuxRhys Hiltner
Updates #35057 Change-Id: Id702b502fa4e4005ba1e450a945bc4420a8a8b8c Reviewed-on: https://go-review.googlesource.com/c/go/+/342052 Run-TryBot: Rhys Hiltner <rhys@justin.tv> TryBot-Result: Go Bot <gobot@golang.org> Reviewed-by: Michael Pratt <mpratt@google.com> Trust: Than McIntosh <thanm@google.com>
2020-09-02runtime: add file copyright header declarationHeisenberg
Some files have no copyright notice. The copyright time is the earliest modification record of the file. Change-Id: I5698bae16b6b73543e074415877a03348f792951 Reviewed-on: https://go-review.googlesource.com/c/go/+/246378 Run-TryBot: Emmanuel Odeke <emm.odeke@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Emmanuel Odeke <emm.odeke@gmail.com>
2020-02-24runtime: remove unused _F_SETFL const on linuxTobias Klauser
This constant is only used on libc-based platforms (aix, darwin, solaris). Change-Id: Ic57d1fe3b1501c5b552eddb9aba11f1e02510082 Reviewed-on: https://go-review.googlesource.com/c/go/+/220421 Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2019-10-20runtime: define nonblockingPipeIan Lance Taylor
This requires defining pipe, pipe2, and setNonblock for various platforms. The new function is currently only used on AIX. It will be used by later CLs in this series. Updates #27707 Change-Id: Id2f987b66b4c66a3ef40c22484ff1d14f58e9b31 Reviewed-on: https://go-review.googlesource.com/c/go/+/171822 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Michael Knyszek <mknyszek@google.com> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2019-03-15runtime: introduce and consistently use setNsec for timespecIan Lance Taylor
The general code for setting a timespec value sometimes used set_nsec and sometimes used a combination of set_sec and set_nsec. Standardize on a setNsec function that takes a number of nanoseconds and splits them up to set the tv_sec and tv_nsec fields. Consistently mark setNsec as go:nosplit, since it has to be that way on some systems including Darwin and GNU/Linux. Consistently use timediv on 32-bit systems to help stay within split-stack limits on processors that don't have a 64-bit division instruction. Change-Id: I6396bb7ddbef171a96876bdeaf7a1c585a6d725b Reviewed-on: https://go-review.googlesource.com/c/go/+/167389 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2018-09-18runtime: use MADV_FREE on Linux if availableTobias Klauser
On Linux, sysUnused currently uses madvise(MADV_DONTNEED) to signal the kernel that a range of allocated memory contains unneeded data. After a successful call, the range (but not the data it contained before the call to madvise) is still available but the first access to that range will unconditionally incur a page fault (needed to 0-fill the range). A faster alternative is MADV_FREE, available since Linux 4.5. The mechanism is very similar, but the page fault will only be incurred if the kernel, between the call to madvise and the first access, decides to reuse that memory for something else. In sysUnused, test whether MADV_FREE is supported and fall back to MADV_DONTNEED in case it isn't. This requires making the return value of the madvise syscall available to the caller, so change runtime.madvise to return it. Fixes #23687 Change-Id: I962c3429000dd9f4a00846461ad128b71201bb04 Reviewed-on: https://go-review.googlesource.com/135395 Run-TryBot: Tobias Klauser <tobias.klauser@gmail.com> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Ian Lance Taylor <iant@golang.org>
2016-09-26runtime: unify handling of alternate signal stackIan Lance Taylor
Change all Unix systems to use stackt for the alternate signal stack (some were using sigaltstackt). Add OS-specific setSignalstackSP function to handle different types for ss_sp field, and unify all OS-specific signalstack functions into one. Unify handling of alternate signal stack in OS-specific minit and sigtrampgo functions via new functions minitSignalstack and setGsignalStack. Change-Id: Idc316dc69b1dd725717acdf61a1cd8b9f33ed174 Reviewed-on: https://go-review.googlesource.com/29757 Run-TryBot: Ian Lance Taylor <iant@golang.org> TryBot-Result: Gobot Gobot <gobot@golang.org> Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
2015-02-25runtime: mark pages we return to kernel as NOHUGEPAGEKeith Randall
We return memory to the kernel with madvise(..., DONTNEED). Also mark returned memory with NOHUGEPAGE to keep the kernel from merging this memory into a huge page, effectively reallocating it. Only known to be a problem on linux/{386,amd64,amd64p32} at the moment. It may come up on other os/arch combinations in the future. Fixes #8832 Change-Id: Ifffc6627a0296926e3f189a8a9b6e4bdb54c79eb Reviewed-on: https://go-review.googlesource.com/5660 Reviewed-by: Dmitry Vyukov <dvyukov@google.com>
2015-02-04runtime: support panic/print logging in android-L.Hyang-Ah Hana Kim
In android-L, logging is done through the logd daemon. If logd daemon is available, send logging to logd. Otherwise, fallback to the legacy mechanism (/dev/log files). This change adds access/socket/connect calls to interact with the logd. Fixes golang/go#9398. Change-Id: I3c52b81b451f5862107d7c675f799fc85548486d Reviewed-on: https://go-review.googlesource.com/3350 Reviewed-by: David Crawshaw <crawshaw@golang.org>
2014-11-19[dev.cc] runtime: add explicit siginfo.si_addr fieldAustin Clements
struct siginfo_t's si_addr field is part of a union. Previously, we represented this union in Go using an opaque byte array and accessed the si_addr field using unsafe (and wrong on 386 and arm!) pointer arithmetic. Since si_addr is the only field we use from this union, this replaces the opaque byte array with an explicit declaration of the si_addr field and accesses it directly. LGTM=minux, rsc R=rsc, minux CC=golang-codereviews https://golang.org/cl/179970044
2014-11-14[dev.cc] runtime: change set_sec to take int64Russ Cox
Fixes build. Tested that all these systems can make.bash. TBR=austin CC=golang-codereviews https://golang.org/cl/177770043
2014-11-14[dev.cc] runtime: fix linux buildRuss Cox
TBR=austin CC=golang-codereviews https://golang.org/cl/176760044
2014-11-11[dev.cc] runtime: convert defs_$GOOS_$GOARCH.h to GoRuss Cox
The conversion was done with an automated tool and then modified only as necessary to make it compile and run. In a few cases, defs_$GOOS_$GOARCH.go already existed, so the target here is defs1_$GOOS_$GOARCH.go. [This CL is part of the removal of C code from package runtime. See golang.org/s/dev.cc for an overview.] LGTM=r R=r CC=austin, dvyukov, golang-codereviews, iant, khr https://golang.org/cl/171490043
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