Add function slabs_reclaim() to reclaim free slabs positively

Henry Lu henrylu21 at gmail.com
Wed Sep 6 02:35:13 UTC 2006


---------- Forwarded message ----------
From: Henry Lu <henrylu21 at gmail.com>
Date: Sep 6, 2006 10:32 AM
Subject: Re: Add function slabs_reclaim() to reclaim free slabs positively
To: Steven Grimm <sgrimm at facebook.com>

 Well, the TODO file in memcached-1.1.12.tar.gz wrote:
* slab class reassignment still buggy and can crash.  once that's
  stable, server should re-assign pages every 60 seconds or so
  to keep all classes roughly equal.  [Update: fixed now?, but
  not heavily tested.  Future: make slab classes, with per-class
  cleaners functions.]

For example, when you insert blocks of 8k into memcached,
and make it full, after a while, a large number of items of 8k expired,
and some slabs in 8k clsid got free.
At that time, I am trying to insert a block of 16k, it fails with 'out of
memory'.
Actually the free slabs contain items of 8k cannot be moved from 8k clsid to
16 clsid.

So I make a 'global_free_slab_list' to contain all free slabs by runing
'slabs_reclaim()' every 5 seconds.




On 9/6/06, Steven Grimm <sgrimm at facebook.com> wrote:
>
> Henry Lu wrote:
> > Hi guys:
> >
> > Slab class reassignment is a big problem for memcached of the latest
> > version(1.1.12).
>
> What problem are you running into, specifically?
>
> -Steve
>
>
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