Re: 2.4.19rc2aa1 VM too aggressive?

[Andrea Arcangeli]

On Tue, Jul 23, 2002 at 02:34:46PM -0700, Stephen Hemminger wrote:
> 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

sorry I thought you were using 2.4.19rc3aa1, -ac reintroduces a number
of vm bugs with the rmap vm that I fixed some age ago, plus it
underperformns in many areas, and about async-io I'm not shipping it.
You should report this to Alan and Ben. I'm interested only about
problems that can be reproduced with mainline and -aa, thanks.

> > can you try:
> > 
> > 	echo 1000 >/proc/sys/vm/vm_mapped_ratio
> 
> That file does not exist in 2.4.19rc3ac3

yes I misunderstood the kernel version.

> 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
> 

Andrea