From: Stephen Hemminger <shemminger@osdl.org>
To: linux-kernel@vger.kernel.org
Subject: Re: splice blocks indefinitely when len > 64k?
Date: Mon, 30 Oct 2006 13:08:13 -0800 [thread overview]
Message-ID: <20061030130813.12b3adc1@freekitty> (raw)
In-Reply-To: 20061030195426.GO14055@kernel.dk
On Mon, 30 Oct 2006 20:54:27 +0100
Jens Axboe <jens.axboe@oracle.com> wrote:
> On Mon, Oct 30 2006, Daniel Drake wrote:
> > Hi,
> >
> > I'm experimenting with splice and have run into some unusual behaviour.
> >
> > I am using the utilities in git://brick.kernel.dk/data/git/splice.git
> >
> > In splice.h, when changing SPLICE_SIZE from:
> >
> > #define SPLICE_SIZE (64*1024)
> >
> > to
> >
> > #define SPLICE_SIZE ((64*1024)+1)
> >
> > splice-cp hangs indefinitely when copying files sized 65537 bytes or
> > more. It hangs on the first splice() call.
> >
> > Is this a bug? I'd like to be able to copy much more than 64kb on a
> > single splice call.
>
> You can't, internally splice is using a pipe which is currently confined
> to 16 pages. The SPLICE_SIZE define isn't a suggestion in the code, it
> reflects that. You could fix splice-cp to not stall on changing that,
> however that still doesn't change the fact that you can only move chunks
> of 64kb (on your arch) right now.
>
It could accept larger values but only move SPLICE_SIZE, assuming
caller checked for partial completions.
--
Stephen Hemminger <shemminger@osdl.org>
next prev parent reply other threads:[~2006-10-30 21:08 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-10-30 16:39 splice blocks indefinitely when len > 64k? Daniel Drake
2006-10-30 19:11 ` Phillip Susi
2006-10-30 19:32 ` Daniel Drake
2006-10-30 19:55 ` Jens Axboe
2006-10-30 19:54 ` Jens Axboe
2006-10-30 21:08 ` Stephen Hemminger [this message]
2006-10-31 7:27 ` Jens Axboe
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