From: Linus Torvalds <torvalds@linux-foundation.org>
To: Nick Piggin <npiggin@suse.de>
Cc: Steven Rostedt <rostedt@goodmis.org>,
Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
Peter Zijlstra <peterz@infradead.org>,
Frederic Weisbecker <fweisbec@gmail.com>,
Pierre Tardy <tardyp@gmail.com>, Ingo Molnar <mingo@elte.hu>,
Arnaldo Carvalho de Melo <acme@redhat.com>,
Tom Zanussi <tzanussi@gmail.com>,
Paul Mackerras <paulus@samba.org>,
linux-kernel@vger.kernel.org, arjan@infradead.org,
ziga.mahkovec@gmail.com, davem <davem@davemloft.net>,
linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
Christoph Lameter <cl@linux-foundation.org>,
Tejun Heo <tj@kernel.org>, Jens Axboe <jens.axboe@oracle.com>
Subject: Re: Unexpected splice "always copy" behavior observed
Date: Wed, 19 May 2010 07:39:11 -0700 (PDT) [thread overview]
Message-ID: <alpine.LFD.2.00.1005190736370.23538@i5.linux-foundation.org> (raw)
In-Reply-To: <20100519063116.GR2516@laptop>
On Wed, 19 May 2010, Nick Piggin wrote:
>
> We can possibly do an attempt to invalidate existing pagecache and
> then try to install the new page.
Yes, but that's going to be rather hairier. We need to make sure that the
filesystem doesn't have some kind of dirty pointers to the old page etc.
Although I guess that should always show up in the page counters, so I
guess we can always handle the case of page_count() being 1 (only page
cache) and the page being unlocked.
So I'd much rather just handle the "append to the end".
The real limitation is likely always going to be the fact that it has to
be page-aligned and a full page. For a lot of splice inputs, that simply
won't be the case, and you'll end up copying for alignment reasons anyway.
Linus
next prev parent reply other threads:[~2010-05-19 14:42 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-05-18 15:34 Mathieu Desnoyers
2010-05-18 15:51 ` Nick Piggin
2010-05-18 15:56 ` Christoph Lameter
2010-05-18 16:00 ` Nick Piggin
2010-05-18 16:13 ` Nick Piggin
2010-05-18 15:53 ` Steven Rostedt
2010-05-18 16:10 ` Steven Rostedt
2010-05-18 16:25 ` Linus Torvalds
2010-05-19 6:31 ` Nick Piggin
2010-05-19 14:39 ` Linus Torvalds [this message]
2010-05-19 14:56 ` Steven Rostedt
2010-05-19 14:59 ` Linus Torvalds
2010-05-19 15:12 ` Steven Rostedt
2010-05-19 15:51 ` Mathieu Desnoyers
2010-05-19 15:33 ` Miklos Szeredi
2010-05-19 15:45 ` Steven Rostedt
2010-05-19 15:55 ` Nick Piggin
2010-05-19 16:01 ` Mathieu Desnoyers
2010-05-19 16:36 ` Steven Rostedt
2010-05-19 15:57 ` Mathieu Desnoyers
2010-05-19 16:27 ` Nick Piggin
2010-05-19 19:14 ` Mathieu Desnoyers
2010-05-19 19:31 ` Linus Torvalds
2010-05-19 21:49 ` Mathieu Desnoyers
2010-05-20 0:04 ` Linus Torvalds
2010-05-20 1:56 ` Mathieu Desnoyers
2010-05-20 14:18 ` Linus Torvalds
2010-05-19 20:59 ` Rick Sherm
2010-05-19 15:17 ` Nick Piggin
2010-05-19 15:30 ` Linus Torvalds
2010-05-19 15:44 ` Nick Piggin
2010-05-19 15:28 ` Miklos Szeredi
2010-05-19 15:32 ` Linus Torvalds
2010-05-19 15:56 ` Miklos Szeredi
2010-05-19 16:01 ` Linus Torvalds
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