On Fri, November 11, 2016 11:11 pm, Jens Axboe wrote: > Respun on top of for-4.10/block, dropping patches that have been > merged. This patchset adds Christoph's simplified sync O_DIRECT bdev access > mode, and implements a more efficient IO polling on top of it. For more > details, see the v2 posting here: > > http://www.mail-archive.com/linux-block@xxxxxxxxxxxxxxx/msg02079.html > > > Changes since v2: > > > - Adapt to blk stat changes > - Make it explicit that only blk-mq supports polling > - Fix a bug in the hrtimer code, switching to absolute mode if we > have to loop around (thanks Omar). > Hi Jens I applied this series cleanly on top of 2868f13c303e147 in your for-4.10/block branch. I tested using a simple fio wrapper script [1] on a low-latency NVMe SSD [2]. Here are some results: io_poll io_poll_delay threads latency CPU/threads 0 N/A 1 17.0 47% 1 -1 1 13.8 100% 1 0 1 14.6 73% 1 10 1 17.0 56% 0 N/A 8 18.7 47% 1 -1 8 14.4 100% 1 0 8 15.7 73% 1 10 8 19.0 56% The io_poll_delay option 0 is definitely a nice compromise between no polling and 100% polling. The result for io_poll_delay=10us is interesting as it implies there might be some mismatch between that value and the completion time. However I think that is something we can improve on over time and I don't see it as a reason to not get this series upstream. For the series: Tested-By: Stephen Bates <sbates@xxxxxxxxxxxx> Reviewed-By: Stephen Bates <sbates@xxxxxxxxxxxx> Cheers Stephen [1] https://github.com/sbates130272/fio-stuff/blob/master/misc/iopoll-test.sh [2] http://www.microsemi.com/products/storage/flashtec-nvram-drives/flashtec-nvram-drives -- 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
