Re: [BUG+FIX] 2.4 buggercache sucks

Martin J. Bligh
2002-08-28T15:28:34Z

Andrew had a new version that he just submitted to 2.5,
but it may not backport easily.

The agreement at OLS was to treat read and write seperately -
nuke them immediately for one side, and reclaim under mem
pressure for the other. Half of Andrea's patch, and half of
Andrew's. Unfortunately I can never remember which was which ;-)
And I don't think anyone has rolled that together yet ....

Summary: the code below probably isn't the desired solution.

M.

--On Wednesday, August 28, 2002 11:28 AM +0200 Roy Sigurd Karlsbakk <roy@karlsbakk.net> wrote:

> hi
>
> the patch below has now been tested out for quite some time.
>
> Will it be likely to see this into 2.4.20?
>
> roy
>
>
> On Friday 24 May 2002 21:32, Andrew Morton wrote:
>> "Martin J. Bligh" wrote:
>> > >> Sounds like exactly the same problem we were having. There are two
>> > >> approaches to solving this - Andrea has a patch that tries to free
>> > >> them under memory pressure, akpm has a patch that hacks them down as
>> > >> soon as you've fininshed with them (posted to lse-tech mailing list).
>> > >> Both approaches seemed to work for me, but the performance of the
>> > >> fixes still has to be established.
>> > >
>> > > Where can I find the akpm patch?
>> >
>> > http://marc.theaimsgroup.com/?l=lse-tech&m=102083525007877&w=2
>> >
>> > > Any plans to merge this into the main kernel, giving a choice
>> > > (in config or /proc) to enable this?
>> >
>> > I don't think Andrew is ready to submit this yet ... before anything
>> > gets merged back, it'd be very worthwhile testing the relative
>> > performance of both solutions ... the more testers we have the
>> > better ;-)
>>
>> Cripes no. It's pretty experimental. Andrea spotted a bug, too. Fixed
>> version is below.
>>
>> It's possible that keeping the number of buffers as low as possible
>> will give improved performance over Andrea's approach because it
>> leaves more ZONE_NORMAL for other things. It's also possible that
>> it'll give worse performance because more get_block's need to be
>> done for file overwriting.
>>