Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262238AbUCXXdj (ORCPT ); Wed, 24 Mar 2004 18:33:39 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262273AbUCXXdj (ORCPT ); Wed, 24 Mar 2004 18:33:39 -0500 Received: from ppp-217-133-42-200.cust-adsl.tiscali.it ([217.133.42.200]:943 "EHLO dualathlon.random") by vger.kernel.org with ESMTP id S262238AbUCXXdi (ORCPT ); Wed, 24 Mar 2004 18:33:38 -0500 Date: Thu, 25 Mar 2004 00:34:30 +0100 From: Andrea Arcangeli To: Dipankar Sarma Cc: "Paul E. McKenney" , Arjan van de Ven , tiwai@suse.de, Robert Love , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH] RCU for low latency (experimental) Message-ID: <20040324233430.GJ2065@dualathlon.random> References: <20040323101755.GC3676@in.ibm.com> <1080038105.5296.8.camel@laptop.fenrus.com> <20040323123105.GI22639@dualathlon.random> <20040323124002.GH3676@in.ibm.com> <20040323125044.GL22639@dualathlon.random> <20040324172657.GA1303@us.ibm.com> <20040324175142.GW2065@dualathlon.random> <20040324213914.GD4539@in.ibm.com> <20040324225326.GH2065@dualathlon.random> <20040324231145.GB12035@in.ibm.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20040324231145.GB12035@in.ibm.com> User-Agent: Mutt/1.4.1i X-GPG-Key: 1024D/68B9CB43 13D9 8355 295F 4823 7C49 C012 DFA1 686E 68B9 CB43 X-PGP-Key: 1024R/CB4660B9 CC A0 71 81 F4 A0 63 AC C0 4B 81 1D 8C 15 C8 E5 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1107 Lines: 24 On Thu, Mar 25, 2004 at 04:41:45AM +0530, Dipankar Sarma wrote: > That was not 16 callbacks per tick, it was 16 callbacks in one > batch of a single softirq. And then I reschedule the RCU tasklet sorry so you're already using tasklets in current code? I misunderstood the current code then. > to process the rest. I am planning to vary this and see if we > should do even less per softirq. yes, I think 16 is too much, the softirq code should just retry 10 times, summing up to 160 callbacks. After you re-arm the tasklet the first time, all other rearmed invocations should probably execute less callbacks than 16. it greatly depends on the number of times we retry a softirq before giving up and offloading the work to ksoftirqd, that number is 10 currently (see MAX_SOFTIRQ_RESTART). The bigger that number, the less callbacks you can execute per tasklet. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/