From: Jens Axboe <jens.axboe@oracle.com>
To: Jamie Lokier <jamie@shareable.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
Max Kellermann <max@duempel.org>,
torvalds@linux-foundation.org, linux-fsdevel@vger.kernel.org,
linux-kernel@vger.kernel.org, npiggin@suse.de
Subject: Re: [patch 0/3] make splice more generic
Date: Fri, 15 May 2009 09:32:06 +0200 [thread overview]
Message-ID: <20090515073206.GW4140@kernel.dk> (raw)
In-Reply-To: <20090514202706.GB20363@shareable.org>
On Thu, May 14 2009, Jamie Lokier wrote:
> Jens Axboe wrote:
> > SPLICE_F_MOVE is a soft flag in that it will move if it
> > can, but not fail if it can't.
>
> According to local man page, it's not even that.
>
> SPLICE_F_MOVE [...] The initial implementation of this flag was buggy:
> therefore starting in Linux 2.6.21 it is a *no-op*
> (but is still permitted in a splice() call); in the
> future, a correct implementation may be restored.
That's a temporary condition, and the statement isn't completely true
either. What happened was that the stealing of fs pages was disabled.
Other users of splice could still implement it and take advantage of it.
Nick pulled the original code and did promise to work on a replacement,
but so far that hasn't happened.
> > Perhaps we should add a flag that does pass back an error if we
> > can't just move pages around, SPLICE_F_STRICT or something like
> > that.
>
> What should it do in cases where the kernel would choose to copy data,
> i.e. data that isn't a whole page?
Probably -EINVAL, like O_DIRECT would.
--
Jens Axboe
prev parent reply other threads:[~2009-05-15 7:32 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-05-07 13:37 [patch 0/3] make splice more generic Miklos Szeredi
2009-05-07 13:37 ` [patch 1/3] splice: implement pipe to pipe splicing Miklos Szeredi
2009-05-07 13:37 ` [patch 2/3] splice: implement default splice_read method Miklos Szeredi
2009-05-13 5:35 ` Andrew Morton
2009-05-13 6:37 ` Jens Axboe
2009-05-13 9:01 ` Miklos Szeredi
2009-05-14 17:29 ` Jens Axboe
2009-05-14 17:54 ` Miklos Szeredi
2009-05-14 18:00 ` Jens Axboe
2009-05-18 12:36 ` Miklos Szeredi
2009-05-19 9:38 ` Jens Axboe
2009-05-07 13:37 ` [patch 3/3] splice: implement default splice_write method Miklos Szeredi
2009-05-07 15:55 ` [patch 0/3] make splice more generic Linus Torvalds
2009-05-11 15:17 ` Miklos Szeredi
2009-05-09 11:36 ` Max Kellermann
2009-05-11 12:12 ` Jens Axboe
2009-05-11 15:22 ` Miklos Szeredi
2009-05-14 20:27 ` Jamie Lokier
2009-05-15 7:32 ` Jens Axboe [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20090515073206.GW4140@kernel.dk \
--to=jens.axboe@oracle.com \
--cc=jamie@shareable.org \
--cc=linux-fsdevel@vger.kernel.org \
--cc=linux-kernel@vger.kernel.org \
--cc=max@duempel.org \
--cc=miklos@szeredi.hu \
--cc=npiggin@suse.de \
--cc=torvalds@linux-foundation.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).