Messages in this thread | | | Date | Thu, 11 Jan 2007 10:08:55 +1100 | From | David Chinner <> | Subject | Re: [REGRESSION] 2.6.19/2.6.20-rc3 buffered write slowdown |
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On Wed, Jan 10, 2007 at 03:04:15PM -0800, Christoph Lameter wrote: > On Thu, 11 Jan 2007, David Chinner wrote: > > > The performance and smoothness is fully restored on 2.6.20-rc3 > > by setting dirty_ratio down to 10 (from the default 40), so > > something in the VM is not working as well as it used to.... > > dirty_background_ratio is left as is at 10?
Yes.
> So you gain performance by switching off background writes via pdflush?
Well, pdflush appears to be doing very little on both 2.6.18 and 2.6.20-rc3. In both cases kswapd is consuming 10-20% of a CPU and all of the pdflush threads combined (I've seen up to 7 active at once) use maybe 1-2% of cpu time. This occurs regardless of the dirty_ratio setting.
Cheers,
Dave. -- Dave Chinner Principal Engineer SGI Australian Software Group - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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