Re: [2.4 BUFFERING BUG] (was [BUG] 2.4 VM sucks. Again)

Roy Sigurd Karlsbakk
2002-07-10T08:11:23Z

On Wednesday 10 July 2002 10:05, Andrew Morton wrote:
> Roy Sigurd Karlsbakk wrote:
> > hi
> >
> > I've been using the patch below from Andrew for some weeks now, sometimes
> > under quite heavy load, and find it quite stable.
>
> Wish we knew why. I've tried many times to reproduce the problem
> which you're seeing. With just two gigs of memory, buffer_heads
> really cannot explain anything. It's weird.

well - firstly, I'm using _1_ gig of memory - highmem (= 900 megs something)
secondly - I have reproduced it on two different installations, although on
the same hardware - standard PC with SiS MB and an extra promise controller,
RAID-0 on 4 drives and chunksize 1MB. Given a 30-50 processes each reading a
4gig file and sending it over HTTP, everything works fine _if_ and only _if_
the client reads at high speed. If, however, the client reads at normal
streaming speed (4,3Mbps), buffers go bOOM.

> We discussed this in Ottawa - I guess Andrea will add the toss-the-buffers
> code on the read side (basically the filemap.c stuff). That may
> be sufficient, but without an understanding of what is going on,
> it is hard to predict.

Is there _any_ more data I can give, or any more testing I can do, then I'll
do my very best to help

roy
--
Roy Sigurd Karlsbakk, Datavaktmester

Computers are like air conditioners.
They stop working when you open Windows.