From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932531AbVHYUKr (ORCPT ); Thu, 25 Aug 2005 16:10:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932533AbVHYUKr (ORCPT ); Thu, 25 Aug 2005 16:10:47 -0400 Received: from ms-smtp-01.nyroc.rr.com ([24.24.2.55]:4350 "EHLO ms-smtp-01.nyroc.rr.com") by vger.kernel.org with ESMTP id S932531AbVHYUKq (ORCPT ); Thu, 25 Aug 2005 16:10:46 -0400 Subject: Re: [RFC] RT-patch update to remove the global pi_lock From: Steven Rostedt To: Ingo Molnar Cc: Thomas Gleixner , LKML , Sven-Thorsten Dietrich , Adrian Bunk , george anzinger , dwalker@mvista.com, Karsten Wiese , "Paul E. McKenney" In-Reply-To: <20050825174732.GA23774@elte.hu> References: <1124704837.5208.22.camel@localhost.localdomain> <20050822101632.GA28803@elte.hu> <1124710309.5208.30.camel@localhost.localdomain> <20050822113858.GA1160@elte.hu> <1124715755.5647.4.camel@localhost.localdomain> <20050822183355.GB13888@elte.hu> <1124739657.5809.6.camel@localhost.localdomain> <1124739895.5809.11.camel@localhost.localdomain> <1124981238.5350.6.camel@localhost.localdomain> <1124982413.5350.19.camel@localhost.localdomain> <20050825174732.GA23774@elte.hu> Content-Type: text/plain Organization: Kihon Technologies Date: Thu, 25 Aug 2005 16:09:23 -0400 Message-Id: <1125000563.6264.10.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.2.3 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 2005-08-25 at 19:47 +0200, Ingo Molnar wrote: > your patch works great here, on 3 separate systems: a 1-way, a 2/4-way > and an 8-way. > > the 1-way system performed so well running the SMP kernel that i first > thought i booted the UP kernel by accident :-) > > on the 8-way box, "hackbench 10" got _3.7_ times faster (!!!). > > i have booted the 8-way box without your patch once more because i didnt > believe the results initially and thought they were some benchmarking > fluke. But no, it wasnt a fluke. The kernel profiles are nicely flat > now. > > i've released 2.6.13-rc7-rt2 with your patch included. This is certainly > a major milestone for PREEMPT_RT, it is now a first-class scalability > citizen on SMP too. Great work Steven! > > Ingo A word of caution (aka. disclaimer). This is still new. I still expect there are some cases in the code that was missed and can cause a dead lock or other bad side effect. Hopefully, we can iron these all out. Also, I noticed that since the task takes it's own pi_lock for most of the code, if something locks up and a NMI goes off, the down_trylock in printk will also lock when it tries to take it's own pi_lock. I stated earlier, that I converted printk to use early_printk (serial) on a oops_in_progress, so I wouldn't need to worry about the unlocking circus that needs to be done. So, I'm sure if something goes wrong now, you won't see anything, even with an NMI. If someone else would like to fix that, I'm sure Ingo would be willing to accept patches :-) -- Steve