Messages in this thread | | | Date | Fri, 13 Aug 2004 12:31:51 +0200 | From | Ingo Molnar <> | Subject | Re: [patch] Latency Tracer, voluntary-preempt-2.6.8-rc4-O6 |
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* Lee Revell <rlrevell@joe-job.com> wrote:
> > > http://redhat.com/~mingo/voluntary-preempt/voluntary-preempt-2.6.8-rc4-O6 > > Ugh, this is a bad one: > > preemption latency trace v1.0 > ----------------------------- > latency: 506 us, entries: 157 (157) > process: evolution/3461, uid: 1000 > nice: 0, policy: 0, rt_priority: 0 > =======> > 0.000ms (+0.000ms): get_random_bytes (__check_and_rekey) [...] > 0.493ms (+0.001ms): local_bh_enable (__check_and_rekey)
indeed this is a new one. Entropy rekeying every 300 seconds. Most of the overhead comes from the memcpy's - 10 usecs a pop!
this could possibly explain some earlier reports of RTC problems every couple of minutes - on slower boxes it could easily be more than the 0.5 msec you got. (and with a 8192 Hz RTC the interrupt period is 122 usecs.)
such bhs-off spinlocked sections exclude all softirq traffic - and in the redirected hardirqs case the hardirqs are excluded too.
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