Re: [Alsa-user] new source of MIDI playback slow-down identified- 5a03b051ed87e72b959f32a86054e1142ac4cf55 thp: use compaction in kswapdfor GFP_ATOMIC order > 0
From: Arthur Marsh
Date: Sun Feb 27 2011 - 03:48:18 EST
Andrea Arcangeli wrote, on 26/02/11 17:13:
On Thu, Feb 24, 2011 at 02:54:05AM +0100, Andrea Arcangeli wrote:
Ok so tomorrow I'll get all results on these 3 kernels (
compaction_alloc_lowlat2) on network server load, where throughout is
measured in addition to latency. Then we'll have a better picture to
Latency is still lowest with compaction-no-kswapd-3. compaction_alloc
still is at the top of the profiling with
compaction-kswapd-3 reduced the overhead somewhat but not enough to be
as fast as with compaction-no-kswapd-3 (even if much better than
So we should apply compaction-no-kswapd-3 to 2.6.38 I think.
I built a kernel based against git head of around 0800 UTC Saturday
2011-02-26 plus compaction-no-kswapd-3 (Andrea's) and
compaction_alloc_lowlat-2 (Mel's) patches.
The the latency performance for MIDI playback is excellent and kswap0
has reported 100 seconds of CPU time in 22 hours of the kernel kernel
However, I am now battling against the kernel freeing up memory when
using icedove/thunderbird. top is reporting 74 MiB resident, 418 MiB
virtual, and as I pause typing to watch top output, free RAM has gone up
to 50 MiB and I'm stuck waiting for parts of icedove to swap back in so
that I can get a response from my input (either scrolling a message when
reading it or composing a message, where I am left waiting for the text
that I typed to appear).
Normally in this machine with only 384 MiB RAM and (say) 2.6.35-2.6.37
kernels, free RAM will hover around the 5 MiB mark when lots of
applications are open. I may wait when switching from one running
application to another for it to respond, but once I am using that
particular application it sufficiently responsive not to be annoying.
The aggressive reclamation of RAM by the kernel I built around 0800 UTC
Saturday is working against the application currently in focus.
I will try Andrea's and Mel's patches built against 2.6.36-rc6 over the
next several hours to see how that compares.
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