diff options
| author | Martin Pieuchot <mpi@cvs.openbsd.org> | 2013-02-11 17:05:26 +0000 |
|---|---|---|
| committer | Martin Pieuchot <mpi@cvs.openbsd.org> | 2013-02-11 17:05:26 +0000 |
| commit | 0bc83736ede1f82c457e48727982eae123b2a215 (patch) | |
| tree | f169dcb391924b9a9743965a7212c6aac4e50a60 /sys/lib | |
| parent | a9adb71cfc4f8563cec7231e996164c74b19585c (diff) | |
Fix kernel profiling on MP systems by using per-CPU buffer. Previously
various CPUs were iterating over the same global buffer at the same
time to modify it and never ended.
This diff includes some ideas submited by Thor Simon to NetBSD via miod@.
ok mikeb@, haesbaert@
Diffstat (limited to 'sys/lib')
| -rw-r--r-- | sys/lib/libkern/mcount.c | 24 |
1 files changed, 16 insertions, 8 deletions
diff --git a/sys/lib/libkern/mcount.c b/sys/lib/libkern/mcount.c index b6421c3cc3d..bcb5c1286bd 100644 --- a/sys/lib/libkern/mcount.c +++ b/sys/lib/libkern/mcount.c @@ -1,4 +1,4 @@ -/* $OpenBSD: mcount.c,v 1.10 2013/01/16 23:38:14 dlg Exp $ */ +/* $OpenBSD: mcount.c,v 1.11 2013/02/11 17:05:25 mpi Exp $ */ /* $NetBSD: mcount.c,v 1.3.6.1 1996/06/12 04:23:01 cgd Exp $ */ /*- @@ -43,13 +43,10 @@ * _mcount updates data structures that represent traversals of the * program's call graph edges. frompc and selfpc are the return * address and function address that represents the given call graph edge. - * - * Note: the original BSD code used the same variable (frompcindex) for - * both frompcindex and frompc. Any reasonable, modern compiler will - * perform this optimization. */ _MCOUNT_DECL(u_long frompc, u_long selfpc) __used; -_MCOUNT_DECL(u_long frompc, u_long selfpc) /* _mcount; may be static, inline, etc */ +/* _mcount; may be static, inline, etc */ +_MCOUNT_DECL(u_long frompc, u_long selfpc) { u_short *frompcindex; struct tostruct *top, *prevtop; @@ -57,9 +54,21 @@ _MCOUNT_DECL(u_long frompc, u_long selfpc) /* _mcount; may be static, inline, et long toindex; #ifdef _KERNEL int s; -#endif + /* + * Do not profile execution if memory for the current CPU + * desciptor and profiling buffers has not yet been allocated + * or if the CPU we are running on has not yet set its trap + * handler. + */ + if (gmoninit == 0) + return; + + if ((p = curcpu()->ci_gmon) == NULL) + return; +#else p = &_gmonparam; +#endif /* * check that we are profiling * and that we aren't recursively invoked. @@ -156,7 +165,6 @@ _MCOUNT_DECL(u_long frompc, u_long selfpc) /* _mcount; may be static, inline, et *frompcindex = toindex; goto done; } - } done: #ifdef _KERNEL |