From: Steve French <smfrench@gmail.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Jeff Layton <jlayton@redhat.com>,
David Howells <dhowells@redhat.com>,
Trond Myklebust <trondmy@hammerspace.com>,
Anna Schumaker <anna.schumaker@netapp.com>,
Steve French <sfrench@samba.org>,
Dominique Martinet <asmadeus@codewreck.org>,
CIFS <linux-cifs@vger.kernel.org>,
ceph-devel@vger.kernel.org, linux-cachefs@redhat.com,
Alexander Viro <viro@zeniv.linux.org.uk>,
linux-mm <linux-mm@kvack.org>,
linux-afs@lists.infradead.org,
v9fs-developer@lists.sourceforge.net,
Christoph Hellwig <hch@lst.de>,
linux-fsdevel <linux-fsdevel@vger.kernel.org>,
linux-nfs <linux-nfs@vger.kernel.org>,
Linus Torvalds <torvalds@linux-foundation.org>,
David Wysochanski <dwysocha@redhat.com>,
LKML <linux-kernel@vger.kernel.org>,
William Kucharski <william.kucharski@oracle.com>
Subject: Re: [PATCH 00/33] Network fs helper library & fscache kiocb API [ver #3]
Date: Mon, 15 Feb 2021 23:22:20 -0600 [thread overview]
Message-ID: <CAH2r5mv+AdiODH1TSL+SOQ5qpZ25n7Ysrp+iYxauX9sD8ehhVQ@mail.gmail.com> (raw)
In-Reply-To: <20210216021015.GH2858050@casper.infradead.org>
On Mon, Feb 15, 2021 at 8:10 PM Matthew Wilcox <willy@infradead.org> wrote:
>
> On Mon, Feb 15, 2021 at 06:40:27PM -0600, Steve French wrote:
> > It could be good if netfs simplifies the problem experienced by
> > network filesystems on Linux with readahead on large sequential reads
> > - where we don't get as much parallelism due to only having one
> > readahead request at a time (thus in many cases there is 'dead time'
> > on either the network or the file server while waiting for the next
> > readpages request to be issued). This can be a significant
> > performance problem for current readpages when network latency is long
> > (or e.g. in cases when network encryption is enabled, and hardware
> > offload not available so time consuming on the server or client to
> > encrypt the packet).
> >
> > Do you see netfs much faster than currentreadpages for ceph?
> >
> > Have you been able to get much benefit from throttling readahead with
> > ceph from the current netfs approach for clamping i/o?
>
> The switch from readpages to readahead does help in a couple of corner
> cases. For example, if you have two processes reading the same file at
> the same time, one will now block on the other (due to the page lock)
> rather than submitting a mess of overlapping and partial reads.
Do you have a simple repro example of this we could try (fio, dbench, iozone
etc) to get some objective perf data?
My biggest worry is making sure that the switch to netfs doesn't degrade
performance (which might be a low bar now since current network file copy
perf seems to signifcantly lag at least Windows), and in some easy to understand
scenarios want to make sure it actually helps perf.
--
Thanks,
Steve
next prev parent reply other threads:[~2021-02-16 5:22 UTC|newest]
Thread overview: 47+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-02-15 15:44 [PATCH 00/33] Network fs helper library & fscache kiocb API [ver #3] David Howells
2021-02-15 15:44 ` [PATCH 01/33] iov_iter: Add ITER_XARRAY David Howells
2021-02-15 15:44 ` [PATCH 02/33] mm: Add an unlock function for PG_private_2/PG_fscache David Howells
2021-02-16 10:26 ` Christoph Hellwig
2021-02-15 15:44 ` [PATCH 03/33] mm: Implement readahead_control pageset expansion David Howells
2021-02-16 10:32 ` Christoph Hellwig
2021-02-16 13:22 ` Matthew Wilcox
2021-02-17 14:36 ` Mike Marshall
2021-02-17 15:42 ` David Howells
2021-02-17 16:59 ` Mike Marshall
2021-02-17 22:20 ` David Howells
2021-02-16 11:48 ` David Howells
2021-02-17 16:13 ` Matthew Wilcox
2021-02-17 22:34 ` David Howells
2021-02-17 22:49 ` Matthew Wilcox
2021-02-18 17:47 ` David Howells
2021-02-15 15:45 ` [PATCH 04/33] vfs: Export rw_verify_area() for use by cachefiles David Howells
2021-02-16 10:26 ` Christoph Hellwig
2021-02-16 11:55 ` David Howells
2021-02-15 15:45 ` [PATCH 05/33] netfs: Make a netfs helper module David Howells
2021-02-15 15:45 ` [PATCH 06/33] netfs, mm: Move PG_fscache helper funcs to linux/netfs.h David Howells
2021-02-15 15:45 ` [PATCH 07/33] netfs, mm: Add unlock_page_fscache() and wait_on_page_fscache() David Howells
2021-02-15 15:45 ` [PATCH 08/33] netfs: Provide readahead and readpage netfs helpers David Howells
2021-02-15 15:45 ` [PATCH 09/33] netfs: Add tracepoints David Howells
2021-02-15 15:46 ` [PATCH 10/33] netfs: Gather stats David Howells
2021-02-15 15:46 ` [PATCH 11/33] netfs: Add write_begin helper David Howells
2021-02-15 15:46 ` [PATCH 12/33] netfs: Define an interface to talk to a cache David Howells
2021-02-15 15:46 ` [PATCH 13/33] netfs: Hold a ref on a page when PG_private_2 is set David Howells
2021-02-15 18:05 ` [PATCH 00/33] Network fs helper library & fscache kiocb API [ver #3] Jeff Layton
2021-02-16 0:40 ` Steve French
2021-02-16 2:10 ` Matthew Wilcox
2021-02-16 5:18 ` Steve French
2021-02-16 5:22 ` Steve French [this message]
2021-02-23 20:27 ` Matthew Wilcox
2021-02-24 4:57 ` Steve French
2021-02-24 13:32 ` David Howells
2021-02-24 15:51 ` Matthew Wilcox
2021-02-16 11:01 ` Jeff Layton
2021-02-15 22:46 ` [PATCH 34/33] netfs: Use in_interrupt() not in_softirq() David Howells
2021-02-16 8:42 ` Christoph Hellwig
2021-02-16 9:06 ` Sebastian Andrzej Siewior
2021-02-16 9:29 ` David Howells
2021-02-16 9:30 ` Christoph Hellwig
2021-02-18 14:02 ` [PATCH 34/33] netfs: Pass flag rather than use in_softirq() David Howells
2021-02-18 15:06 ` Marc Dionne
2021-02-18 15:16 ` Marc Dionne
2021-02-19 9:01 ` Sebastian Andrzej Siewior
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