> Il giorno 12 dic 2018, alle ore 22:41, stan <stanl-fedorauser@xxxxxxxxxxx> ha scritto: > > On Wed, 12 Dec 2018 16:07:49 -0500 > Jeff Moyer <jmoyer@xxxxxxxxxx> wrote: > > Thanks for your insight. Doesn't look good for my use of BFQ. > >> Note that you can change the current I/O scheduler for any block >> device by echo-ing into /sys/block/<dev>/queue/scheduler. Cat-ing >> that file will give you the list of available schedulers. > > That's part of the problem. BFQ doesn't appear in the list of > available schedulers. When I cat that location for my disks, I see > [noop]. Since CFQ does appear there if it is compiled into the kernel, > I'll have to look into what is done for CFQ and see how hard it would > be to patch the kernel to repeat that behavior for BFQ. > > My use case in not mq, so after reading one of the links in this > thread about performance, I saw that BFQ gave ~20 to 30 % boost in > disk io performance, and enhanced low latency performance (desktop > responsiveness) for single queue. That's what I want to capture by using > BFQ. I wonder if that is my problem. From what Chris said, an mq > scheduler is required in order to use BFQ, whether it is for mq or > single queue use. I'll try that. I normally use deadline and CFQ for > scheduling. Back to the compiler. > > I'm surprised this is so difficult. It's been in the kernel since the > 2.x series, and usually the configuration options are excellent for > allowing variation in how the kernel is configured. > > On the plus side, I notice only slight degradation in behavior using > noop scheduling. :-) Maybe I should just skip scheduling. :-D To test the behavior of your system, why don't you check, e.g., how long it takes to start an application while there is some background I/O? A super quick way to do this is git clone https://github.com/Algodev-github/S cd S/comm_startup_lat sudo ./comm_startup_lat.sh <scheduler-you-want-to-test> 5 5 seq 3 "replay-startup-io gnometerm" The last command line - starts the reading of 5 files plus the writing of 5 other files - replays, for three times, the I/O that gnome terminal does while; starting up (if you want I can tell you how to change the last command line so as to execute the original application, but you would get the same results); - for each attempt, measures how long this start-up I/O takes to complete. Paolo > _______________________________________________ > kernel mailing list -- kernel@xxxxxxxxxxxxxxxxxxxxxxx > To unsubscribe send an email to kernel-leave@xxxxxxxxxxxxxxxxxxxxxxx > Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html > List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines > List Archives: https://lists.fedoraproject.org/archives/list/kernel@xxxxxxxxxxxxxxxxxxxxxxx _______________________________________________ devel mailing list -- devel@xxxxxxxxxxxxxxxxxxxxxxx To unsubscribe send an email to devel-leave@xxxxxxxxxxxxxxxxxxxxxxx Fedora Code of Conduct: https://getfedora.org/code-of-conduct.html List Guidelines: https://fedoraproject.org/wiki/Mailing_list_guidelines List Archives: https://lists.fedoraproject.org/archives/list/devel@xxxxxxxxxxxxxxxxxxxxxxx
