[lkml]   [2016]   [Oct]   [19]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH v6 0/3] Enabling ATA Command Priorities
On Mon, Oct 17, 2016 at 11:27:27AM -0700, Adam Manzanares wrote:
> This patch builds ATA commands with high priority if the iocontext of a process
> is set to real time. The goal of the patch is to improve tail latencies of
> workloads that use higher queue depths. This requires setting the iocontext
> ioprio on the request when it is initialized
> This patch has been tested with an Ultrastar HE8 HDD and cuts the
> the p99.99 tail latency of foreground IO from 2s down to 72ms when
> using the deadline scheduler. This patch works independently of the
> scheduler so it can be used with all of the currently available
> request based schedulers.
> Foreground IO, for the previously described results, is an async fio job
> submitting 4K read requests at a QD of 1 to the HDD. The foreground IO is set
> with the iopriority class of real time. The background workload is another fio
> job submitting read requests at a QD of 32 to the same HDD with default
> iopriority.
> This feature is enabled for ATA devices by setting the ata ncq_prio_on device
> attribute to 1. An ATA device is also checked to see if the device supports per
> command priority.

Applied 1-3 to libata/for-4.10 w/ some modifications.



 \ /
  Last update: 2016-10-19 20:39    [W:0.073 / U:0.728 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site