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Subject: Re: 2.4.19rc2aa1 VM too aggressive?
From: Stephen Hemminger <shemminger@osdl.org>
To: Andrea Arcangeli <andrea@suse.de>
Cc: Johannes Erdfelt <johannes@erdfelt.com>,
       Mark Hahn <hahn@physics.mcmaster.ca>, linux-kernel@vger.kernel.org
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On Tue, 2002-07-23 at 13:33, Andrea Arcangeli wrote:

> some seldom swapout is ok, the strange thing are those small
> swapins/swapouts. I also assume it's writing using write(2), not with
> map_shared+msync.

I am using ben's lahaise new AIO which effectively maps the pages in
before the i/o. Using normal I/O I don't see swapping, the cached peaks
at about .827028

> 
> can you try:
> 
> 	echo 1000 >/proc/sys/vm/vm_mapped_ratio

That file does not exist in 2.4.19rc3ac3
bash-2.05$ ls /proc/sys/vm 
bdflush  max_map_count  min-readahead      page-cluster
kswapd   max-readahead  overcommit_memory  pagetable_cache
> 
> I also wonder if you've quite some amount of mapped address space durign
> the benchmark. In such case there's no trivial way around it, the vm
> will constantly found tons of mapped address space, and it will trigger
> some swapouts, however the swapins shouldn't happen so fast in such
> case.
The AIO will pin some space, but the upper bound should be 
	NIO(16) * Record Size(64k) = 1 Meg


> In any case the sysctl will allow you to tune for your workload.
> 
> Andrea


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