Re: REGRESSION: Performance regressions from switching anon_vma->lockto mutex
From: Andi Kleen
Date: Wed Jun 15 2011 - 16:57:34 EST
7.44% exim [kernel.kallsyms] [k] format_decode
|
--- format_decod
This is a glibc issue. exim calls libdb and libdb asks sysconf for the
number of CPUs to tune
its locking, and glibc reads /proc/stat. And /proc/stat is incredible slow.
I would blame glibc, but in this case it's really the kernel to blame
for not providing proper
interface.
This was my motivation for the sysconf() syscall I submitted some time ago.
https://lkml.org/lkml/2011/5/13/455
Anyways a quick workaround is to use this LD_PRELOAD:
http://halobates.de/smallsrc/sysconf.c
But it's not 100% equivalent.
-Andi
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