Re: experiences with 2.5.40 on a busy usenet news server

From: Nick Sanders (sandersn@btinternet.com)
Date: Tue Oct 08 2002 - 04:22:33 EST


On Tuesday 08 October 2002 9:46 am, Miquel van Smoorenburg wrote:
> Just FYI:
>
> So I booted 2.5.40 with the raid0 fix on our usenet news peering
> server yesterday. It is a box that exchanges binary feeds with
> about 40 peers, 400 GB/day in, 600 GB/day out.
>
> It's a dual PIII/450, 1 GB RAM, 4x18 GB article spool directly
> on partitions (not raw, but normal partitions). INN-2.4/CNFS.
>
> With 2.4.19, it runs fine. With 2.5.40, it goes wildly into
> swap. I'm assuming the I/O is pushing the newsserver binaries
> and database mappings into swap.
>
> # free
> total used free shared buffers cached
> Mem: 1033308 1027316 5992 0 836884 29776
> -/+ buffers/cache: 160656 872652
> Swap: 976888 364032 612856
>
> No need to swap 364 MB when there's 872 MB still free...
> This makes the machine dogslow. An 'expire' process that
> runs every night normally takes 15 minutes to finish now
> has been running for 10 hours and its still not finished.
>
> Article acceptance rate has halved, the machine can't keep up
> with the binaries it is fed.
>
> I'm going to risk corrupting the databases and reboot back
> to 2.4.19 now.
>
You might want to try 2.5.40-mm2

[snip]
- Started work on /proc/sys/vm/swappiness. Setting it to 100% gives
  you current 2.5 behaviour. Setting it to 0 feels pretty similar to
  2.4.19.
[snip]

then you would be able to test different swap behaviours

i.e echo 0 > /proc/sys/vm/swappiness for 2.4.19 behaviour

Nick
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