Messages in this thread | | | Date | Wed, 19 May 2010 13:59:16 -0700 (PDT) | From | Rick Sherm <> | Subject | Re: Unexpected splice "always copy" behavior observed |
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Sorry for deleting CC'd addresses. yahoo was whining...
--- On Wed, 5/19/10, Linus Torvalds <torvalds@linux-foundation.org> wrote:
> From: Linus Torvalds <torvalds@linux-foundation.org> > Subject: Re: Unexpected splice "always copy" behavior observed > To: "Steven Rostedt" <rostedt@goodmis.org> > Cc: "Nick Piggin" <npiggin@suse.de>, "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> > Date: Wednesday, May 19, 2010, 2:59 PM > > > On Wed, 19 May 2010, Steven Rostedt wrote: > > > On Wed, 2010-05-19 at 07:39 -0700, Linus Torvalds > wrote: > > > > > 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. > > > > That's understandable. For the use cases of splice I > use, I work to make > > it page aligned and full pages. Anyone else using > splice for > > optimizations, should do the same. It only makes > sense. > > > > The end of buffer may not be a full page, but then > it's the end anyway, > > and I'm not as interested in the speed. > > Btw, since you apparently have a real case - is the "splice > to file" > always just an append? IOW, if I'm not right in assuming > that the only > sane thing people would reasonable care about is "append to > a file", then > holler now. >
I've a similar 'append' use case: http://marc.info/?l=linux-kernel&m=127143736527459&w=4
My mmapped buffers are pinned down.
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