Arthur Marsh wrote: > I'm experiencing MIDI playback slow-downs when I'm observing kswapd0 > active (a few percent of cpu in top output) in recent kernels. > > I git-bisected the problem down to: > > commit 5a03b051ed87e72b959f32a86054e1142ac4cf55 > Author: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Date: Thu Jan 13 15:47:11 2011 -0800 > > thp: use compaction in kswapd for GFP_ATOMIC order > 0 > > This takes advantage of memory compaction to properly generate pages of > order > 0 if regular page reclaim fails and priority level becomes more > severe and we don't reach the proper watermarks. > > Signed-off-by: Andrea Arcangeli <aarcange@xxxxxxxxxx> > Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> > Signed-off-by: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> > > I ran git-bisect over the weekend, building and installing ALSA 1.0.24 > with each kernel. After identifying the above commit, I rebuilt the 2.6 > head with that commit reverted and verified that the problem was no > longer present. Apparently, huge page compaction disables interrupts for much too long. > MIDI playback was via aplaymidi -p 17:0 to a Soundblaster Audigy 2 ZS > (SB0350) wavetable. The ALSA sequencer uses either the system timer or an HR timer at 1 kHz to deliver MIDI commands (notes); the wavetable driver requires its own interrupts in regular 5.3 ms intervals. Regards, Clemens ------------------------------------------------------------------------------ Index, Search & Analyze Logs and other IT data in Real-Time with Splunk Collect, index and harness all the fast moving IT data generated by your applications, servers and devices whether physical, virtual or in the cloud. Deliver compliance at lower cost and gain new business insights. Free Software Download: http://p.sf.net/sfu/splunk-dev2dev _______________________________________________ Alsa-user mailing list Alsa-user@xxxxxxxxxxxxxxxxxxxxx https://lists.sourceforge.net/lists/listinfo/alsa-user
