Re: [patch] voluntary-preempt-2.6.9-rc1-bk12-R5

[Ingo Molnar]

* Lee Revell <rlrevell@xxxxxxxxxxx> 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
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