Messages in this thread | | | Subject | Re: [patch] voluntary-preempt-2.6.9-rc1-bk12-R5 | From | Lee Revell <> | Date | Sun, 05 Sep 2004 17:03:12 -0400 |
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On Sun, 2004-09-05 at 15:12, Ingo Molnar wrote: > * Lee Revell <rlrevell@joe-job.com> wrote: > > > Ok, first new one in a while. This was with -R0, but I haven't seen > > anyone else report it. Let me know if you need the complete trace. > > > > preemption latency trace v1.0.2 > > ------------------------------- > > latency: 511 us, entries: 951 (951) > > ----------------- > > | task: dbench/4810, uid:1000 nice:0 policy:0 rt_prio:0 > > ----------------- > > => started at: kill_pg_info+0x10/0x50 > > => ended at: kill_pg_info+0x2e/0x50 > > =======> > > 00000001 0.000ms (+0.000ms): kill_pg_info (sys_kill) > > 00000001 0.000ms (+0.000ms): __kill_pg_info (kill_pg_info) > > 00000001 0.000ms (+0.000ms): find_pid (__kill_pg_info) > > this is quite hard to fix - lots of processes were SIGKILL-ed (or > SIGTERM-ed) and the signal semantics require us to deliver signals > atomically. The only fix would be to turn the signal locks into > semaphores but that's quite hard. (it's also a bit problematic for > interrupt-delivered signals.) > > Ingo >
Here is a histogram I generated using realfeel2. This should provide better data than my jackd histograms because the latter are dependent on the ALSA driver, jackd's design, etc.
I had to modify the amlat utilities to use usecs instead of msecs, this is a very good sign. ;-)
http://krustophenia.net/testresults.php?dataset=2.6.9-rc1-R0#/var/www/2.6.9-rc1-R0/foo.hist
I find the two smaller spikes to either side of the central spike really odd. These showed up in my jackd tests too, I had attributed them to some measurement artifact, but they seem real. Maybe a rounding bug, or some kind of weird cache effect?
Lee
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