On Tue, 2007-09-25 at 18:21 +0530, Srivatsa Vaddagiri wrote: > On Tue, Sep 25, 2007 at 12:36:17PM +0200, Ingo Molnar wrote: > > hm. perhaps this fixup in kernel/sched.c:set_task_cpu(): > > > > p->se.vruntime -= old_rq->cfs.min_vruntime - > > new_rq->cfs.min_vruntime; > > This definitely does need some fixup, even though I am not sure yet if > it will solve completely the latency issue. > > I tried the following patch. I *think* I see some improvement, wrt > latency seen when I type on the shell. Before this patch, I noticed > oddities like "kill -9 chew-max-pid" wont kill chew-max (it is queued in > runqueue waiting for a looong time to run before it can acknowledge > signal and exit). With this patch, I don't see such oddities ..So I am hoping > it fixes the latency problem you are seeing as well.
http://lkml.org/lkml/2007/9/25/117 plus the below seems to be the SIlver Bullet for the latencies I was seeing. > Index: current/kernel/sched.c > =================================================================== > --- current.orig/kernel/sched.c > +++ current/kernel/sched.c > @@ -1039,6 +1039,8 @@ void set_task_cpu(struct task_struct *p, > { > int old_cpu = task_cpu(p); > struct rq *old_rq = cpu_rq(old_cpu), *new_rq = cpu_rq(new_cpu); > + struct cfs_rq *old_cfsrq = task_cfs_rq(p), > + *new_cfsrq = cpu_cfs_rq(old_cfsrq, new_cpu); > u64 clock_offset; > > clock_offset = old_rq->clock - new_rq->clock; > @@ -1051,7 +1053,8 @@ void set_task_cpu(struct task_struct *p, > if (p->se.block_start) > p->se.block_start -= clock_offset; > #endif > - p->se.vruntime -= old_rq->cfs.min_vruntime - new_rq->cfs.min_vruntime; > + p->se.vruntime -= old_cfsrq->min_vruntime - > + new_cfsrq->min_vruntime; > > __set_task_cpu(p, new_cpu); > } > > > -- > Regards, > vatsa - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
