Messages in this thread | | | Date | Mon, 14 Nov 2011 13:47:17 -0500 | From | Dave Jones <> | Subject | Re: long sleep_on_page delays writing to slow storage |
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On Thu, Nov 10, 2011 at 10:34:42AM +0100, Johannes Weiner wrote:
> > I wonder if a change like this would be enough? > > > > sync_migration = !(gfp_mask & __GFP_NO_KSWAPD); > > > > But even if hidden in a new function, the main downside overall is the > > fact we'll pass one more var through the stack of fast paths. > > > > Johannes I recall you reported this too and Mel suggested the above > > change, did it help in the end? > > Yes, it completely fixed the latency problem. > > That said, I haven't looked at the impact on the THP success rate, but > a regression there is probably less severe than half-minute-stalls in > interactive applications.
FWIW, we've had a few reports from Fedora users since we moved to 3.x kernels about similar problems, so whatever the fix is for this should probably go to stable too.
I could push an update for Fedora users to test the change above if that would be helpful ?
Dave
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