Re: [MMTests] IO metadata on XFS

From: Mel Gorman
Date: Tue Jul 03 2012 - 07:44:24 EST

On Tue, Jul 03, 2012 at 11:59:51AM +0100, Mel Gorman wrote:
> > Can you run latencytop to see
> > if there is excessive starvation/wait times for allocation
> > completion?
> I'm not sure what format you are looking for. latencytop is shit for
> capturing information throughout a test and it does not easily allow you to
> record a snapshot of a test. You can record all the console output of course
> but that's a complete mess. I tried capturing /proc/latency_stats over time
> instead because that can be trivially sorted on a system-wide basis but
> as I write this I find that latency_stats was bust. It was just spitting out
> Latency Top version : v0.1
> and nothing else. Either latency_stats is broken or my config is. Not sure
> which it is right now and won't get enough time on this today to pinpoint it.

PEBKAC. Script that monitored /proc/latency_stats was not enabling
latency top via /proc/sys/kernel/latencytop

Mel Gorman
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