Messages in this thread | | | Subject | Re: x86, mce, Use user return notifier in mce | From | Huang Ying <> | Date | Sat, 21 Jan 2012 14:19:30 +0800 |
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On Fri, 2012-01-20 at 21:56 -0800, Tejun Heo wrote: > Hello, > > On Fri, Jan 20, 2012 at 6:44 PM, Huang Ying <ying.huang@intel.com> wrote: > > It appears that WQ_HIGHPRI only provides priority between work queue, > > not between the work queue backing kthread and other tasks. Is there > > any mechanism for that? > > No, it doesn't. > > > If my understanding was correct, WQ_MEM_RECLAIM has some side-effect for > > that. Because hardware errors occurs seldom, the reserved kthread for > > WQ_MEME_RECLAIM just sleeps most of the time. When first hardware error > > occurs and the work item is queued, the reserved kthread is waked up. > > Because the reserved kthread sleeps for long time, it is highly possible > > for it to be scheduled at the next schedule point. > > But rescuer is used only under memory pressure. It doesn't help latency at all. > > > Because hardware error usually has no locality, WQ_UNBOUND can be used > > for it so that the work item can be put on relative low-load CPU. From > > the document, it is said WQ_UNBOUND work items will be executed ASAP > > too. Compared with WQ_HIGHPRI, how about the priority of WQ_UNBOUND? > > Maybe, maybe not. I suggest just using WQ_HIGHPRI for now and worrying > about it later if the scheduling latency actually turns out to matter.
This is a performance issue. So maybe we need to measure the actual latency firstly. The first step can be using WQ_HIGHPRI as you suggested.
Thanks for your information!
Best Regards, Huang Ying
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