From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Gregory Haskins" Subject: Re: [(RT RFC) PATCH v2 1/9] allow rt-mutex lock-stealing to includelateral priority Date: Mon, 03 Mar 2008 08:41:17 -0700 Message-ID: <47CBD5CD.BA47.005A.0@novell.com> References: <20080225155959.11268.35541.stgit@novell1.haskins.net> <20080225160043.11268.83915.stgit@novell1.haskins.net> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 8BIT Cc: , , , , , , , , "Moiz Kohari" , "Peter Morreale" , "Sven Dietrich" , , , , , , , , To: "Steven Rostedt" Return-path: Received: from sinclair.provo.novell.com ([137.65.248.137]:31210 "EHLO sinclair.provo.novell.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754646AbYCCPsd convert rfc822-to-8bit (ORCPT ); Mon, 3 Mar 2008 10:48:33 -0500 In-Reply-To: Content-Disposition: inline Sender: linux-rt-users-owner@vger.kernel.org List-ID: >>> On Mon, Mar 3, 2008 at 10:13 AM, in message , Steven Rostedt wrote: > > See the issue. The RT task on CPU0 may experience huge latencies. Agreed, but equal priority threads can always cause unbounded latencies by definition. I.e. we only guarantee to the highest thread. > Remember, RT is worried about latencies over performance. > If we can not ***guarantee*** a bounded latency, then, I don't care > how good the perfomance is, it is not good enough for RT. > > > That said, here's the compromise. > > Non-RT tasks care more about overall perfomance than worst case latencies. > So.... See imbedded: This isn't a bad idea, but note that it means RT tasks will not get a performance boost, which is quite substantial. Note that I have substantially cleaned up this patch for the drop I will make later this week (v3). -Greg