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LibC: Make gettid() cache the thread ID in thread-local-storage

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This makes gettid() very cheap, compared to the cost of having to do
a syscall every time.
This commit is contained in:
Andreas Kling 2019-09-14 11:37:58 +02:00
parent ec5091fa7d
commit 161cb89e87
1 changed files with 5 additions and 2 deletions
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7
Libraries/LibC/unistd.cpp
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@ -538,10 +538,13 @@ int ftruncate(int fd, off_t length)
__RETURN_WITH_ERRNO(rc, rc, -1); __RETURN_WITH_ERRNO(rc, rc, -1);
} }
__thread int t_cached_tid = -1;
int gettid() int gettid()
{ {
int rc = syscall(SC_gettid); if (t_cached_tid == -1)
__RETURN_WITH_ERRNO(rc, rc, -1); t_cached_tid = syscall(SC_gettid);
return t_cached_tid;
} }
int donate(int tid) int donate(int tid)