lkml.org 
[lkml]   [2011]   [Jun]   [11]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
SubjectRe: [PATCH net-next-2.6] snmp: reduce percpu needs by 50%
From
From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Sat, 11 Jun 2011 07:45:51 +0200

> SNMP mibs use two percpu arrays, one used in BH context, another in USER
> context. With increasing number of cpus in machines, and fact that ipv6
> uses per network device ipstats_mib, this is consuming a lot of memory
> if many network devices are registered.
>
> commit be281e554e2a (ipv6: reduce per device ICMP mib sizes) shrinked
> percpu needs for ipv6, but we can reduce memory use a bit more.
>
> With recent percpu infrastructure (irqsafe_cpu_inc() ...), we no longer
> need this BH/USER separation since we can update counters in a single
> x86 instruction, regardless of the BH/USER context.
>
> Other arches than x86 might need to disable irq in their
> irqsafe_cpu_inc() implementation : If this happens to be a problem, we
> can make SNMP_ARRAY_SZ arch dependent, but a previous poll
> ( https://lkml.org/lkml/2011/3/17/174 ) to arch maintainers did not
> raise strong opposition.
>
> Only on 32bit arches, we need to disable BH for 64bit counters updates
> done from USER context (currently used for IP MIB)
>
> This also reduces vmlinux size :
>
> 1) x86_64 build
> $ size vmlinux.before vmlinux.after
> text data bss dec hex filename
> 7853650 1293772 1896448 11043870 a8841e vmlinux.before
> 7850578 1293772 1896448 11040798 a8781e vmlinux.after
>
> 2) i386 build
> $ size vmlinux.before vmlinux.afterpatch
> text data bss dec hex filename
> 6039335 635076 3670016 10344427 9dd7eb vmlinux.before
> 6037342 635076 3670016 10342434 9dd022 vmlinux.afterpatch
>
> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>

Looks good to me, applied, thanks Eric.


\
 
 \ /
  Last update: 2011-06-12 01:27    [W:0.036 / U:0.396 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site