From: Andrew Morton <akpm@linux-foundation.org>
To: Jeremy Allison <jra@samba.org>
Cc: Christoph Hellwig <hch@infradead.org>,
Milosz Tanski <milosz@adfin.com>,
linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org,
linux-aio@kvack.org, Mel Gorman <mgorman@suse.de>,
Volker Lendecke <Volker.Lendecke@sernet.de>,
Tejun Heo <tj@kernel.org>, Jeff Moyer <jmoyer@redhat.com>,
Theodore Ts'o <tytso@mit.edu>, Al Viro <viro@zeniv.linux.org.uk>,
linux-api@vger.kernel.org,
Michael Kerrisk <mtk.manpages@gmail.com>,
linux-arch@vger.kernel.org, Dave Chinner <david@fromorbit.com>
Subject: Re: [PATCH v7 0/5] vfs: Non-blockling buffered fs read (page cache only)
Date: Mon, 30 Mar 2015 13:37:58 -0700 [thread overview]
Message-ID: <20150330133758.d2788f6de72f121170ff0301@linux-foundation.org> (raw)
In-Reply-To: <20150330203227.GA4987@samba2>
On Mon, 30 Mar 2015 13:32:27 -0700 Jeremy Allison <jra@samba.org> wrote:
> On Mon, Mar 30, 2015 at 01:26:25PM -0700, Andrew Morton wrote:
> >
> > cons:
> >
> > d) fincore() is more expensive
> >
> > e) fincore() will very occasionally block
>
> The above is the killer for Samba. If fincore
> returns true but when we schedule the pread
> we block, we're hosed.
>
> Once we block, we're done serving clients on the main
> thread until this returns. That can cause unpredictable
> response times which can cause client timeouts.
>
> A fincore+pread solution that blocks is simply unsafe
> to use for us. We'll have to stay with the threadpool :-(.
Finally. Thanks ;)
This implies that the samba main thread also has to avoid any memory
allocations both direct and within syscall and pagefault - those will
occasionally exhibit similar worse-case latency. Is this done now?
next prev parent reply other threads:[~2015-03-30 20:38 UTC|newest]
Thread overview: 108+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-03-16 18:27 [PATCH v7 0/5] vfs: Non-blockling buffered fs read (page cache only) Milosz Tanski
2015-03-16 18:27 ` [PATCH v7 1/5] vfs: Prepare for adding a new preadv/pwritev with user flags Milosz Tanski
2015-03-16 18:27 ` Milosz Tanski
2015-03-16 21:05 ` Andreas Dilger
2015-03-16 21:05 ` Andreas Dilger
2015-03-16 18:27 ` [PATCH v7 2/5] vfs: Define new syscalls preadv2,pwritev2 Milosz Tanski
2015-03-16 18:27 ` Milosz Tanski
2015-03-16 18:27 ` [PATCH v7 3/5] x86: wire up preadv2 and pwritev2 Milosz Tanski
2015-03-16 18:27 ` Milosz Tanski
2015-03-16 18:27 ` [PATCH v7 4/5] vfs: RWF_NONBLOCK flag for preadv2 Milosz Tanski
2015-03-16 18:27 ` Milosz Tanski
2015-03-16 18:27 ` [PATCH v7 5/5] xfs: add RWF_NONBLOCK support Milosz Tanski
2015-03-16 18:27 ` Milosz Tanski
2015-03-16 22:04 ` Dave Chinner
2015-03-16 22:04 ` Dave Chinner
2015-03-16 18:32 ` [PATCH] Add preadv2/pwritev2 documentation Milosz Tanski
2015-03-16 18:32 ` Milosz Tanski
2015-03-27 16:49 ` Andrew Morton
2015-03-27 16:49 ` Andrew Morton
[not found] ` <20150327094932.31b5c9fc.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2015-03-30 7:33 ` Christoph Hellwig
2015-03-30 7:33 ` Christoph Hellwig
[not found] ` <cover.1426528417.git.milosz-B5zB6C1i6pkAvxtiuMwx3w@public.gmane.org>
2015-03-16 18:34 ` [PATCH] fstests: generic test for preadv2 behavior on linux Milosz Tanski
2015-03-16 18:34 ` Milosz Tanski
2015-03-16 21:07 ` Andreas Dilger
2015-03-16 21:07 ` Andreas Dilger
2015-03-16 22:03 ` Milosz Tanski
2015-03-16 22:02 ` Dave Chinner
2015-03-16 22:02 ` Dave Chinner
2015-03-16 22:11 ` Milosz Tanski
2015-03-16 22:11 ` Milosz Tanski
[not found] ` <CANP1eJEj2buvwaU-jum=GROowY6DrysQ0NU+weXstn=83yVspQ-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-16 22:56 ` Dave Chinner
2015-03-16 22:56 ` Dave Chinner
2015-03-27 3:28 ` [PATCH v7 0/5] vfs: Non-blockling buffered fs read (page cache only) Andrew Morton
2015-03-27 3:28 ` Andrew Morton
2015-03-27 5:41 ` Volker Lendecke
2015-03-27 5:41 ` Volker Lendecke
[not found] ` <E1YbN1J-0084qO-3s-dqLtpHMqGvUyWpdLl23E4A@public.gmane.org>
2015-03-27 6:08 ` Andrew Morton
2015-03-27 6:08 ` Andrew Morton
[not found] ` <20150326230833.4ccfaebb.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2015-03-27 8:02 ` Volker Lendecke
2015-03-27 8:02 ` Volker Lendecke
2015-03-27 8:12 ` Christoph Hellwig
2015-03-27 8:12 ` Christoph Hellwig
2015-03-27 8:18 ` Christoph Hellwig
2015-03-27 8:18 ` Christoph Hellwig
[not found] ` <20150327081822.GA28669-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-03-27 8:35 ` Andrew Morton
2015-03-27 8:35 ` Andrew Morton
2015-03-27 8:48 ` Christoph Hellwig
2015-03-27 8:48 ` Christoph Hellwig
[not found] ` <20150327084833.GA7689-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-03-27 9:01 ` Andrew Morton
2015-03-27 9:01 ` Andrew Morton
2015-03-27 9:44 ` Volker Lendecke
2015-03-27 9:44 ` Volker Lendecke
2015-03-27 15:58 ` Jeremy Allison
2015-03-27 15:58 ` Jeremy Allison
2015-03-27 16:30 ` Andrew Morton
2015-03-27 16:30 ` Andrew Morton
2015-03-27 16:39 ` Jeremy Allison
2015-03-27 16:39 ` Jeremy Allison
2015-03-27 16:39 ` Andrew Morton
2015-03-27 16:39 ` Andrew Morton
2015-03-27 16:45 ` Milosz Tanski
2015-03-27 16:45 ` Milosz Tanski
2015-03-31 1:27 ` Milosz Tanski
2015-03-27 16:38 ` Milosz Tanski
2015-03-27 16:38 ` Milosz Tanski
2015-03-30 7:36 ` Christoph Hellwig
2015-03-30 7:36 ` Christoph Hellwig
[not found] ` <20150330073604.GB22229-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>
2015-03-30 17:19 ` Jeremy Allison
2015-03-30 17:19 ` Jeremy Allison
2015-03-30 22:51 ` Milosz Tanski
2015-03-30 20:26 ` Andrew Morton
2015-03-30 20:26 ` Andrew Morton
2015-03-30 20:32 ` Jeremy Allison
2015-03-30 20:37 ` Andrew Morton [this message]
2015-03-30 20:49 ` Jeremy Allison
2015-03-30 20:49 ` Jeremy Allison
2015-03-30 21:33 ` Andrew Morton
2015-03-30 22:35 ` Milosz Tanski
2015-03-30 22:35 ` Milosz Tanski
2015-03-30 22:49 ` Milosz Tanski
2015-03-30 22:57 ` Andrew Morton
[not found] ` <20150330155700.92f4c8a0bf13418aaf01ae04-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2015-03-30 23:06 ` Milosz Tanski
2015-03-30 23:06 ` Milosz Tanski
2015-03-30 23:25 ` Milosz Tanski
2015-03-30 23:25 ` Milosz Tanski
2015-04-04 3:42 ` Andrew Morton
2015-04-04 3:42 ` Andrew Morton
[not found] ` <20150403204209.75405f37.akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
2015-04-06 3:53 ` Milosz Tanski
2015-04-06 3:53 ` Milosz Tanski
2015-03-30 23:09 ` Milosz Tanski
2015-03-30 23:09 ` Milosz Tanski
2015-03-27 15:21 ` Milosz Tanski
2015-03-27 15:21 ` Milosz Tanski
2015-03-27 17:04 ` Andrew Morton
2015-03-27 17:04 ` Andrew Morton
2015-03-30 7:40 ` Christoph Hellwig
2015-03-30 7:40 ` Christoph Hellwig
2015-03-30 18:54 ` Andrew Morton
2015-03-30 22:40 ` Milosz Tanski
[not found] ` <CANP1eJH4BcZ0vgZ6pZdKOd4orEzfKUqjpKXb3m=WMy0mbK+PFA-JsoAwUIsXosN+BqQ9rBEUg@public.gmane.org>
2015-03-30 22:50 ` Andrew Morton
2015-03-30 22:50 ` Andrew Morton
2015-03-26 11:55 ` Christoph Hellwig
2015-03-26 11:55 ` Christoph Hellwig
2015-03-26 19:12 ` Milosz Tanski
2015-03-26 19:12 ` Milosz Tanski
2015-03-27 2:26 ` Milosz Tanski
2015-03-27 2:29 ` Milosz Tanski
2015-03-27 2:29 ` Milosz Tanski
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