> On Thu, Apr 15, 2010 at 01:09:01PM +0900, KOSAKI Motohiro wrote:
> > Hi
> >
> > > How about this? For now, we stop direct reclaim from doing writeback
> > > only on order zero allocations, but allow it for higher order
> > > allocations. That will prevent the majority of situations where
> > > direct reclaim blows the stack and interferes with background
> > > writeout, but won't cause lumpy reclaim to change behaviour.
> > > This reduces the scope of impact and hence testing and validation
> > > the needs to be done.
> >
> > Tend to agree. but I would proposed slightly different algorithm for
> > avoind incorrect oom.
> >
> > for high order allocation
> > allow to use lumpy reclaim and pageout() for both kswapd and direct reclaim
>
> SO same as current.
Yes. as same as you propsed.
>
> > for low order allocation
> > - kswapd: always delegate io to flusher thread
> > - direct reclaim: delegate io to flusher thread only if vm pressure is low
>
> IMO, this really doesn't fix either of the problems - the bad IO
> patterns nor the stack usage. All it will take is a bit more memory
> pressure to trigger stack and IO problems, and the user reporting the
> problems is generating an awful lot of memory pressure...
This patch doesn't care stack usage. because
- again, I think all stack eater shold be diet.
- under allowing lumpy reclaim world, only deny low order reclaim
doesn't solve anything.
Please don't forget priority=0 recliam failure incvoke OOM-killer.
I don't imagine anyone want it.
And, Which IO workload trigger <6 priority vmscan?
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