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| author | Ian Lance Taylor <ian@gcc.gnu.org> | 2019-05-31 17:56:36 +0000 |
|---|---|---|
| committer | Ian Lance Taylor <ian@gcc.gnu.org> | 2019-05-31 17:56:36 +0000 |
| commit | 4d12cf3cc3143843225ecdb0e5048fc7c37b1574 (patch) | |
| tree | 30d27f1ac980671a5b890c86e562a746f4f4b54e /libgo/runtime/runtime.h | |
| parent | 34a13a521e3fc6f46fcaf2f158d20e66874e99fd (diff) | |
| download | gcc-4d12cf3cc3143843225ecdb0e5048fc7c37b1574.zip gcc-4d12cf3cc3143843225ecdb0e5048fc7c37b1574.tar.gz gcc-4d12cf3cc3143843225ecdb0e5048fc7c37b1574.tar.bz2 | |
runtime: implement cheaper context switch on Linux/AMD64
Currently, goroutine switches are implemented with libc
getcontext/setcontext functions, which saves/restores the machine
register states and also the signal context. This does more than
what we need, and performs an expensive syscall.
This CL implements a simplified version of getcontext/setcontext,
in assembly, that only saves/restores the necessary part, i.e.
the callee-save registers, and the PC, SP. A simplified version
of makecontext, written in C, is also added. Currently this is
only implemented on Linux/AMD64.
Reviewed-on: https://go-review.googlesource.com/c/gofrontend/+/178298
From-SVN: r271818
Diffstat (limited to 'libgo/runtime/runtime.h')
| -rw-r--r-- | libgo/runtime/runtime.h | 17 |
1 files changed, 17 insertions, 0 deletions
diff --git a/libgo/runtime/runtime.h b/libgo/runtime/runtime.h index 71c1a3e..a421dea 100644 --- a/libgo/runtime/runtime.h +++ b/libgo/runtime/runtime.h @@ -510,3 +510,20 @@ bool probestackmaps(void) // older versions of glibc when a SIGPROF signal arrives while // collecting a backtrace. extern uint32 __go_runtime_in_callers; + +// Cheaper context switch functions. Currently only defined on +// Linux/AMD64. +#if defined(__x86_64__) && defined(__linux__) && !defined(__CET__) +typedef struct { + uint64 regs[8]; +} __go_context_t; +int __go_getcontext(__go_context_t*); +int __go_setcontext(__go_context_t*); +void __go_makecontext(__go_context_t*, void (*)(), void*, size_t); +#else +#define __go_context_t ucontext_t +#define __go_getcontext(c) getcontext(c) +#define __go_setcontext(c) setcontext(c) +#define __go_makecontext(c, fn, sp, size) \ + ((c)->uc_stack.ss_sp = sp, (c)->uc_stack.ss_size = size, makecontext(c, fn, 0)) +#endif |