Messages in this thread | | | Date | Thu, 28 Apr 2011 14:42:35 +0100 | From | Mel Gorman <> | Subject | Re: [PATCH 00/13] Swap-over-NBD without deadlocking |
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On Thu, Apr 28, 2011 at 03:31:55PM +0200, Pavel Machek wrote: > Hi! > > > > For testing swap-over-NBD, a machine was booted with 2G of RAM with a > > swapfile backed by NBD. 16*NUM_CPU processes were started that create > > anonymous memory mappings and read them linearly in a loop. The total > > size of the mappings were 4*PHYSICAL_MEMORY to use swap heavily under > > memory pressure. Without the patches, the machine locks up within > > minutes and runs to completion with them applied. > > > > Comments? > > Nice! > > It is easy to see why swapping needs these fixes, but... dirty memory > writeout is used for memory clearing, too. Are same changes neccessary > to make that safe? >
Dirty page limiting covers the MAP_SHARED cases and are already throttled approprately.
> (Perhaps raise 'max dirty %' for testing?)
Stress testing passed for dirty ratios of 40% at least. Maybe it would cause issues when raised to nearly 100% but I don't think that is a particularly interesting use case.
-- Mel Gorman SUSE Labs
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