lkml.org 
[lkml]   [2016]   [Aug]   [4]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v2] mm/slab: Improve performance of gathering slabinfo stats
On Thu,  4 Aug 2016 12:01:13 -0700 Aruna Ramakrishna <aruna.ramakrishna@oracle.com> wrote:

> On large systems, when some slab caches grow to millions of objects (and
> many gigabytes), running 'cat /proc/slabinfo' can take up to 1-2 seconds.
> During this time, interrupts are disabled while walking the slab lists
> (slabs_full, slabs_partial, and slabs_free) for each node, and this
> sometimes causes timeouts in other drivers (for instance, Infiniband).
>
> This patch optimizes 'cat /proc/slabinfo' by maintaining a counter for
> total number of allocated slabs per node, per cache. This counter is
> updated when a slab is created or destroyed. This enables us to skip
> traversing the slabs_full list while gathering slabinfo statistics, and
> since slabs_full tends to be the biggest list when the cache is large, it
> results in a dramatic performance improvement. Getting slabinfo statistics
> now only requires walking the slabs_free and slabs_partial lists, and
> those lists are usually much smaller than slabs_full. We tested this after
> growing the dentry cache to 70GB, and the performance improved from 2s to
> 5ms.

I assume this is tested on both slab and slub?

It isn't the smallest of patches but given the seriousness of the
problem I think I'll tag it for -stable backporting.

\
 
 \ /
  Last update: 2016-08-05 00:01    [W:0.088 / U:0.400 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site