linux-kernel - Re: Are Linux pipes slower than the FreeBSD ones ?

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Message-Id: <200803060302.07084.nickpiggin@yahoo.com.au>
Date:	Thu, 6 Mar 2008 03:02:06 +1100
From:	Nick Piggin <nickpiggin@...oo.com.au>
To:	"Ray Lee" <ray-lk@...rabbit.org>
Cc:	"Eric Dumazet" <dada1@...mosbay.com>,
	"David Miller" <davem@...emloft.net>, dmantipov@...dex.ru,
	linux-kernel@...r.kernel.org
Subject: Re: Are Linux pipes slower than the FreeBSD ones ?

On Thursday 06 March 2008 02:55, Ray Lee wrote:
> On Wed, Mar 5, 2008 at 7:38 AM, Nick Piggin <nickpiggin@...oo.com.au> wrote:

> >  Yeah, but why does the pipe inode need to have its times updated?
> >  I guess there is some reason... hopefully not C&P related.
>
> In principle so that the reader or writer can find out the last time
> the other end did any processing of the pipe. And yeah, for POSIX
> compliance: "Upon successful completion, pipe() will mark for update
> the st_atime, st_ctime and st_mtime fields of the pipe. "

Thanks.

> But it'd be 
> nice if there were a way to avoid touching it more than once a second
> (note the 'will mark for update' language). Or if the pipe is a
> physical FIFO on a noatime filesystem?

I doubt it really matters for anything except this test. I wouldn't
bother doing anything fancy really. It just caught my eye and I was
wondering why it was there at all.

Thanks,
Nick

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