From: Jens Axboe <axboe@suse.de>
To: Oleg Nesterov <oleg@tv-sign.ru>
Cc: linux-kernel@vger.kernel.org, Linus Torvalds <torvalds@osdl.org>,
Ingo Molnar <mingo@elte.hu>
Subject: Re: splice(SPLICE_F_MOVE) problems
Date: Tue, 2 May 2006 07:28:50 +0200 [thread overview]
Message-ID: <20060502052850.GP3814@suse.de> (raw)
In-Reply-To: <20060502001118.GA88@oleg>
On Tue, May 02 2006, Oleg Nesterov wrote:
> On 05/01, Jens Axboe wrote:
> >
> > > If readahead doesn't work, SPLICE_F_MOVE is problematic too.
> > > add_to_page_cache_lru()->lru_cache_add() first increments
> > > page->count and adds this page to lru_add_pvecs. This means
> > > page_cache_pipe_buf_steal()->remove_mapping() will probably
> > > fail.
> >
> > Because of the temporarily elevated page count?
>
> Yes.
>
> On the other hand, if readahead doesn't work we already have a
> bigger problem, and SPLICE_F_MOVE is not garanteed, so I think
> this is very minor.
Yes, clearly readahead has to work as expected. I haven't noticed any
problems, even on half cached workloads. With your handle_ra_miss()
addition and possibly killing the redundant !offset || nr_pages check,
it should be fine.
--
Jens Axboe
next prev parent reply other threads:[~2006-05-02 5:28 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-05-01 6:59 splice(SPLICE_F_MOVE) problems Oleg Nesterov
2006-05-01 6:54 ` Jens Axboe
2006-05-01 19:06 ` Oleg Nesterov
2006-05-01 17:41 ` Jens Axboe
2006-05-02 0:11 ` Oleg Nesterov
2006-05-02 5:28 ` Jens Axboe [this message]
2006-05-03 4:14 ` Oleg Nesterov
2006-05-03 6:56 ` Jens Axboe
2006-05-03 14:35 ` Oleg Nesterov
2006-05-03 10:48 ` Jens Axboe
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