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Subject: Re: splice: move balance_dirty_pages_ratelimited() outside of  
	splice actor
From: Peter Zijlstra <peterz@infradead.org>
To: Jens Axboe <jens.axboe@oracle.com>
Cc: Andrew Morton <akpm@linux-foundation.org>, linux-kernel@vger.kernel.org
In-Reply-To: <20070612121047.GB18832@kernel.dk>
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Date: Tue, 12 Jun 2007 14:16:12 +0200
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On Tue, 2007-06-12 at 14:10 +0200, Jens Axboe wrote:
> On Tue, Jun 12 2007, Peter Zijlstra wrote:
> > On Tue, 2007-06-12 at 13:31 +0200, Jens Axboe wrote:
> > 
> > > Would you prefer this change, then? I'd prefer keeping the current code,
> > > unless it's absolutely critical that we call
> > > balance_dirty_pages_ratelimited() for each and every page instead of eg
> > > every 16 pages here.
> > 
> > For that we should call:
> >   balance_dirty_pages_ratelimited_nr(mapping, nr);
> > 
> > Which is ok, for small nr.
> 
> OK, then this should be better:
> 
> diff --git a/fs/splice.c b/fs/splice.c
> index 25ec9c8..ed40967 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -844,6 +883,9 @@ generic_file_splice_write_nolock(struct pipe_inode_info *pipe, struct file *out,
>  	sd.file = out;
>  	ret = __splice_from_pipe(pipe, &sd, pipe_to_file);
>  	if (ret > 0) {
> +		unsigned long nr_pages;
> +
> +		nr_pages = (ret + PAGE_CACHE_SIZE - 1) >> PAGE_CACHE_SHIFT;

perhaps?
	nr_pages = DIV_ROUND_UP(ret, PAGE_CACHE_SIZE); 

not sure how horrid that turns out to be; you never know with gcc.

Otherwise, looks good.