Date: Thu, 13 Apr 2017 14:58:54 +0300 From: Slawa Olhovchenkov <slw@zxy.spb.ru> To: Adrian Chadd <adrian.chadd@gmail.com> Cc: "stable@freebsd.org" <stable@freebsd.org> Subject: Re: Lock contention in AIO Message-ID: <20170413115854.GZ70430@zxy.spb.ru> In-Reply-To: <CAJ-VmonmHDACnnOvVSwwQffnoUYO5q=aa-gferfaHXVUe7-1aQ@mail.gmail.com> References: <20170321164227.GE86500@zxy.spb.ru> <CAJ-VmonmHDACnnOvVSwwQffnoUYO5q=aa-gferfaHXVUe7-1aQ@mail.gmail.com>
next in thread | previous in thread | raw e-mail | index | archive | help
On Wed, Apr 12, 2017 at 05:21:02PM -0700, Adrian Chadd wrote: > It's the same pages, right? Perhaps. > Is it just the refcounting locking that's > causing it? Don't know. > I think the biggest thing here is to figure out how to have pages have > a lifecycle where the refcount can be inc/dec (obviously >1, ie not in > a state where you can dec to 0) via atomics, without grabbing a lock. > That'll make this particular use case muuuuch faster. > > (dfbsd does this.) I can try you patch. > -a > > > On 21 March 2017 at 09:42, Slawa Olhovchenkov <slw@zxy.spb.ru> wrote: > > I am see lock contetntion cuased by aio read (same file segment from > > multiple process simultaneous): > > > > 07.74% [26756] lock_delay @ /boot/kernel/kernel > > 92.21% [24671] __mtx_lock_sleep > > 52.14% [12864] vm_page_enqueue > > 100.0% [12864] vm_fault_hold > > 87.71% [11283] vm_fault_quick_hold_pages > > 100.0% [11283] vn_io_fault1 > > 100.0% [11283] vn_io_fault > > 99.88% [11270] aio_process_rw > > 100.0% [11270] aio_daemon > > 100.0% [11270] fork_exit > > 00.12% [13] dofileread > > 100.0% [13] kern_readv > > > > Is this know problem? > > _______________________________________________ > > freebsd-stable@freebsd.org mailing list > > https://lists.freebsd.org/mailman/listinfo/freebsd-stable > > To unsubscribe, send any mail to "freebsd-stable-unsubscribe@freebsd.org"
Want to link to this message? Use this URL: <https://mail-archive.FreeBSD.org/cgi/mid.cgi?20170413115854.GZ70430>