Re: [patch 1/3] raid5: offload stripe handle to workqueue

From: Tejun Heo
Date: Tue Jul 30 2013 - 09:58:00 EST


On Tue, Jul 30, 2013 at 09:07:08PM +0800, Shaohua Li wrote:
> Ok, I should explain here. I can't add a work_struct for each stripe, because
> this will stress workqueue very hard. My system handles > 1M/s stripes, which
> makes workqueue pool lock contended very hard.

It doesn't have to be embedding work_struct in each stripe and
schduling them altogether. It's more about scheduling "work units"
rather than "workers" - ie. letting each scheduled work item handle
single work unit rather than making it dispatch multiple work items.
It may make controlling concurrency a bit more interesting but you can
always do it with workqueue_set_max_active(), which is the intended
usage anyway.


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