Adam, On Tue, Dec 06, 2016 at 09:18:01AM -0800, Adam Manzanares wrote: > From: Adam Manzanares <adam.manzanares@xxxxxxx> > > 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_enable > device attribute to 1. An ATA device is also checked to see if the device > supports per command priority. > > v7: > - Run ncq prio support check when sysfs variable set (zero day bug fix) > - Fixes from TJ merged in > - Merge fix for linux-next incorporated The previous version has already been merged into libata/for-4.10. Can you please send me an incremental patch on top of it? The tree can be fetched from git://git.kernel.org/pub/scm/linux/kernel/git/tj/libata.git for-4.10 Thanks. -- tejun -- To unsubscribe from this list: send the line "unsubscribe linux-block" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
