Dave Chinner <dchin...@redhat.com> writes: > On Tue, Oct 02, 2012 at 10:52:05AM +0200, Lukáš Czerner wrote: >> On Mon, 1 Oct 2012, Jeff Moyer wrote: >> > Date: Mon, 01 Oct 2012 12:52:19 -0400 >> > From: Jeff Moyer <jmo...@redhat.com> >> > To: Lukas Czerner <lczer...@redhat.com> >> > Cc: Jens Axboe <ax...@kernel.dk>, linux-kernel@vger.kernel.org, >> > Dave Chinner <dchin...@redhat.com> >> > Subject: Re: [PATCH] loop: Limit the number of requests in the bio list >> > >> > Lukas Czerner <lczer...@redhat.com> writes: >> > >> > > Currently there is not limitation of number of requests in the loop bio >> > > list. This can lead into some nasty situations when the caller spawns >> > > tons of bio requests taking huge amount of memory. This is even more >> > > obvious with discard where blkdev_issue_discard() will submit all bios >> > > for the range and wait for them to finish afterwards. On really big loop >> > > devices this can lead to OOM situation as reported by Dave Chinner. >> > > >> > > With this patch we will wait in loop_make_request() if the number of >> > > bios in the loop bio list would exceed 'nr_requests' number of requests. >> > > We'll wake up the process as we process the bios form the list. >> > >> > I think you might want to do something similar to what is done for >> > request_queues by implementing a congestion on and off threshold. As >> > Jens writes in this commit (predating the conversion to git): >> >> Right, I've had the same idea. However my first proof-of-concept >> worked quite well without this and my simple performance testing did >> not show any regression.
Did you look at system time? -Jeff -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
