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85f64f3851
Thanks to @autumnjolitz (in #876) the Cosmopolitan codebase is now acquainted with Apple's outstanding ulock system calls which offer something much closer to futexes than Grand Central Dispatch which wasn't quite as good, since its wait function can't be interrupted by signals (therefore necessitating a busy loop) and it also needs semaphore objects to be created and freed. Even though ulock is an internal Apple API, strictly speaking, the benefits of futexes are so great that it's worth the risk for now especially since we have the GCD implementation still as a quick escape hatch if it changes Here's why this change is important for x86 XNU users. Cosmo has a suboptimal polyfill when the operating system doesn't offer an API that let's us implement futexes properly. Sadly we had to use that on X86 XNU until now. The polyfill works using clock_nanosleep, to poll the futex in a busy loop with exponential backoff. On XNU x86 clock_nanosleep suffers from us not being able to use a fast clock gettime implementation, which had a compounding effect that's made the polyfill function even more poorly. On X86 XNU we also need to polyfill sched_yield() using select(), which made things even more troublesome. Now that we have futexes we don't have any busy loops anymore for both condition variables and thread joining so optimal performance is attained. To demonstrate, consider these benchmarks Before: $ ./lockscale_test.com -b consumed 38.8377 seconds real time and 0.087131 seconds cpu time After: $ ./lockscale_test.com -b consumed 0.007955 seconds real time and 0.011515 seconds cpu time Fixes #876
77 lines
2.2 KiB
C
77 lines
2.2 KiB
C
#ifndef COSMOPOLITAN_LIBC_CALLS_STRACE_INTERNAL_H_
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#define COSMOPOLITAN_LIBC_CALLS_STRACE_INTERNAL_H_
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#include "libc/intrin/likely.h"
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#include "libc/runtime/runtime.h"
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#define _NTTRACE 0 /* not configurable w/ flag yet */
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#define _POLLTRACE 0 /* not configurable w/ flag yet */
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#define _DATATRACE 1 /* not configurable w/ flag yet */
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#define _LOCKTRACE 0 /* not configurable w/ flag yet */
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#define _STDIOTRACE 0 /* not configurable w/ flag yet */
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#define _KERNTRACE 0 /* not configurable w/ flag yet */
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#define _TIMETRACE 0 /* not configurable w/ flag yet */
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#define STRACE_PROLOGUE "%rSYS %6P %6H %'18T "
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#if !(__ASSEMBLER__ + __LINKER__ + 0)
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COSMOPOLITAN_C_START_
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#ifdef SYSDEBUG
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#define STRACE(FMT, ...) \
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do { \
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if (UNLIKELY(strace_enter())) { \
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__stracef(STRACE_PROLOGUE FMT "\n", ##__VA_ARGS__); \
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ftrace_enabled(+1); \
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} \
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} while (0)
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#else
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#define STRACE(FMT, ...) (void)0
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#endif
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#if defined(SYSDEBUG) && _DATATRACE
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#define DATATRACE(FMT, ...) STRACE(FMT, ##__VA_ARGS__)
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#else
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#define DATATRACE(FMT, ...) (void)0
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#endif
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#if defined(SYSDEBUG) && _POLLTRACE
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#define POLLTRACE(FMT, ...) STRACE(FMT, ##__VA_ARGS__)
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#else
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#define POLLTRACE(FMT, ...) (void)0
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#endif
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#if defined(SYSDEBUG) && _KERNTRACE
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#define KERNTRACE(FMT, ...) STRACE(FMT, ##__VA_ARGS__)
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#else
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#define KERNTRACE(FMT, ...) (void)0
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#endif
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#if defined(SYSDEBUG) && _STDIOTRACE
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#define STDIOTRACE(FMT, ...) STRACE(FMT, ##__VA_ARGS__)
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#else
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#define STDIOTRACE(FMT, ...) (void)0
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#endif
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#if defined(SYSDEBUG) && _NTTRACE
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#define NTTRACE(FMT, ...) STRACE("\e[2m" FMT "\e[0m", ##__VA_ARGS__)
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#else
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#define NTTRACE(FMT, ...) (void)0
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#endif
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#if defined(SYSDEBUG) && _LOCKTRACE
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#define LOCKTRACE(FMT, ...) STRACE(FMT, ##__VA_ARGS__)
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#else
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#define LOCKTRACE(FMT, ...) (void)0
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#endif
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#if defined(SYSDEBUG) && _TIMETRACE
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#define TIMETRACE(FMT, ...) STRACE(FMT, ##__VA_ARGS__)
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#else
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#define TIMETRACE(FMT, ...) (void)0
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#endif
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void __stracef(const char *, ...);
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COSMOPOLITAN_C_END_
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#endif /* !(__ASSEMBLER__ + __LINKER__ + 0) */
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#endif /* COSMOPOLITAN_LIBC_CALLS_STRACE_INTERNAL_H_ */
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