On Thu, May 29 2014 at 7:52pm -0400, Mikulas Patocka <mpatocka@xxxxxxxxxx> wrote: > > > On Tue, 27 May 2014, Jens Axboe wrote: > > > On 2014-05-27 10:26, Mikulas Patocka wrote: > > > On Tue, 27 May 2014, Jens Axboe wrote: > > > > > > > On 2014-05-27 09:23, Mikulas Patocka wrote: > > > > > > > > > The patch adds bio list flushing to the scheduler just besides plug > > > > > flushsing. > > > > > > > > ... which is exactly why I'm commenting. It'd be great to avoid yet one > > > > more > > > > scheduler hook for this sort of thing. > > > > > > > > -- > > > > Jens Axboe > > > > > > One could create something like schedule notifier chain, but I'm not sure > > > if it is worth the complexity because of just two users. If more users > > > come in the future, it could be generalized. > > > > Except such a thing already exists, there are unplug callback chains. All I'm > > asking is that you look into how feasible it would be to use something like > > that, instead of reinventing the wheel. > > > > -- > > Jens Axboe > > > You can use this patch as an example that moves current->bio_list to > struct plug, but I don't recommend to put it in the kernel - this patch > still has some issues (some lvm raid tests fail). Mikulas, Could it be that cond_resched() wasn't unplugging? As was recently raised in this thread: https://lkml.org/lkml/2015/9/18/378 Chris Mason's patch from that thread fixed this issue... I _think_ Linus has since committed Chris' work but I haven't kept my finger on the pulse of that issue. FYI, I've put rebased versions of your 2 patches in my wip branch, see: http://git.kernel.org/cgit/linux/kernel/git/snitzer/linux.git/log/?h=wip I tweaked the 2nd patch that adds bio_list to plug so that generic_make_request's checks for in_generic_make_request isn't racey (your original patch could happen to have current-plug set but in_generic_make_request not yet set). Anyway, I'm just dusting off your earlier work and seeing if I can make sense of a way forward that meets Jens' approval. Jens, if adding a bio_list to struct blk_plug isn't what you were after either please be more specific on what you would like to see... Thanks, Mike -- dm-devel mailing list dm-devel@xxxxxxxxxx https://www.redhat.com/mailman/listinfo/dm-devel
