Messages in this thread | | | Date | Wed, 15 Jun 2011 13:57:29 -0700 | From | Andi Kleen <> | Subject | Re: REGRESSION: Performance regressions from switching anon_vma->lock to mutex |
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> 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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