Messages in this thread | | | Date | Fri, 30 May 2014 11:51:05 -0400 | From | Tejun Heo <> | Subject | Re: [PATCH RFC - TAKE TWO - 12/12] block, bfq: boost the throughput with random I/O on NCQ-capable HDDs |
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On Thu, May 29, 2014 at 11:05:43AM +0200, Paolo Valente wrote: > This patch is basically the counterpart of patch 13 for NCQ-capable > rotational devices. Exactly as patch 13 does on flash-based devices > and for any workload, this patch disables device idling on rotational > devices, but only for random I/O. More precisely, idling is disabled > only for constantly-seeky queues (see patch 7). In fact, only with > these queues disabling idling boosts the throughput on NCQ-capable > rotational devices. > > To not break service guarantees, idling is disabled for NCQ-enabled > rotational devices and constantly-seeky queues only when the same > symmetry conditions as in patch 13, plus an additional one, hold. The > additional condition is related to the fact that this patch disables > idling only for constantly-seeky queues. In fact, should idling be
Wouldn't it make more sense to limit queue depth to one unless the workload can clearly benefit from allowing higher queue depth? And I really think it'd bring more clarity if we just concentrate on rotational devices.
Thanks.
-- tejun
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