linux-kernel - Re: [PATCH][RFC] dynamic pipe resizing

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Date:	Mon, 27 Aug 2007 10:50:45 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	Jan Engelhardt <jengelh@...putergmbh.de>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH][RFC] dynamic pipe resizing

On Fri, Aug 24 2007, Jan Engelhardt wrote:
> 
> On Aug 24 2007 10:52, Jens Axboe wrote:
> >Hi,
> >
> >Dabbling around with splice a bit, I added some code to change the size
> >of a pipe. Currently it's hardcoded as 16 pages, with this patch you can
> >shrink (if you wanted) or grow (the likely scenario) if you want to
> >increase the size of your in-kernel buffer for splice operations.
> 
> Wonderful, I just did the same {-.-}
> (but then dropped the patch because it did not help my application at all,
> so never mind).
> 
> >Like with my original splice patches from 2005, I used fcntl()
> >F_GETPIPE_SZ and F_SETPIPE_SZ to change the size of the pipe. I'm not
> >particularly fond of that interface, so suggestions on how to improve it
> >would be appreciated. Even if fcntl() should be the preferred approach,
> >I think it would be better to pass in a byte based value instead of a
> >number of pages.
> 
> And using  % pipe->buffers then?

I'd probably prefer sticking to power-of-2 array sizes, so just round it
up appropriately. But it's likely not a big deal.

-- 
Jens Axboe

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