Re: Make pipe data structure be a circular list of pages, rather than

From: Lee Revell <rlrevell@joe-job.com>
To: Linus Torvalds <torvalds@osdl.org>
Cc: Chris Friesen <cfriesen@nortelnetworks.com>,
	Mike Waychison <Michael.Waychison@Sun.COM>,
	Alan Cox <alan@lxorguk.ukuu.org.uk>,
	Oleg Nesterov <oleg@tv-sign.ru>,
	William Lee Irwin III <wli@holomorphy.com>,
	Linux Kernel Mailing List <linux-kernel@vger.kernel.org>
Subject: Re: Make pipe data structure be a circular list of pages, rather than
Date: Sat, 08 Jan 2005 17:02:49 -0500	[thread overview]
Message-ID: <1105221769.24592.118.camel@krustophenia.net> (raw)
In-Reply-To: <Pine.LNX.4.58.0501081345440.2386@ppc970.osdl.org>

On Sat, 2005-01-08 at 13:51 -0800, Linus Torvalds wrote:
> 
> On Sat, 8 Jan 2005, Lee Revell wrote:
> > 
> > Many latency critical apps use (tmpfs mounted) FIFO's for IPC; the Linux
> > FIFO being one of the fastest known IPC mechanisms.  Each client in the
> > JACK (http://jackit.sf.net) graph wakes the next one by writing a single
> > byte to a FIFO.  Ardour's GUI, control, and audio threads interact via a
> > similar mechanism.  How would you expect this change to impact the inter
> > thread wakeup latency?  It's confusing when people say "performance",
> > meaning "increased throughput albeit with more latency".  For many
> > people that's a regression.
> 
> I posted the performance numbers in the thread already, and with every
> single throughput number I also talked abotu what the latency difference
> was. So quite frankly, if you were confused, I suspect it was because you
> didn't read them. Tssk, tssk.
> 

How embarassing, I found that message immediately after hitting send.
Looks like a big win.  I'll try the JACK stress test on it just to make
sure.

Lee