Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761426AbYARNeS (ORCPT ); Fri, 18 Jan 2008 08:34:18 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1759143AbYARNeJ (ORCPT ); Fri, 18 Jan 2008 08:34:09 -0500 Received: from py-out-1112.google.com ([64.233.166.181]:8437 "EHLO py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757594AbYARNeH (ORCPT ); Fri, 18 Jan 2008 08:34:07 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=message-id:date:from:reply-to:user-agent:mime-version:to:cc:subject:references:in-reply-to:content-type:content-transfer-encoding; b=gyo6iUiXpU9ee4qccUWDlHJVLjZWihGU5WIdmYxjf+W9wVET2yWfs4/gvbJEuMB3M+Fd9Yco6ZIP7CH+1DG/mD8CDvwxtdR+cmsoSJ5eCkhuu55s7GgAhctZlw32i0+IB9l36VepoiSTCOv/maZcSwPDBlVtHRQ+I5ZpH7Qr7jc= Message-ID: <4790AAC7.2080703@gmail.com> Date: Fri, 18 Jan 2008 08:33:59 -0500 From: Gregory Haskins Reply-To: gregory.haskins@gmail.com User-Agent: Thunderbird 2.0.0.9 (Windows/20071031) MIME-Version: 1.0 To: Mark Hansen CC: linux-kernel@vger.kernel.org, Ingo Molnar , rostedt@goodmis.org Subject: Re: priority based thread wakeup References: In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2472 Lines: 72 Mark Hansen wrote: > Hello, > > Firstly, may I apologise as I am not a member of the LKML, and ask that > I be CC'd in any responses that may be forthcoming. > > My question concerns the following patch which was incorporated into the > 2.6.22 kernel (quoted from that change log): > >> Today, all threads waiting for a given futex are woken in FIFO >> order (first waiter woken first) instead of priority order. >> >> This patch makes use of plist (pirotity ordered lists) instead >> of simple list in futex_hash_bucket. >> >> All non-RT threads are stored with priority MAX_RT_PRIO, causing >> them to be woken last, in FIFO order (RT-threads are woken first, >> in priority order). >> >> Signed-off-by: Sebastien Dugue >> Signed-off-by: Pierre Peiffer > > After updating to this version of the kernel, I was able to observe the > above fix, where multiple RT threads invoking pthread_cond_wait(), and > the highest priority thread will acquire the mutex first, after the > thread holding the mutex calls pthread_cond_signal(); > pthread_mutex_unlock() > > However, since kernel 2.6.23, it seems that the functionality relating > to this "priority based wakeup" has disappeared. > > I understand there have been significant changes in this kernel > concerning the "Completely Fair Scheduler" replacing the "mainline" > scheduler; however my understanding is that the RT functionality would > be preserved. This does not appear to be the case based on repeating the > experiment described above. > > I was wondering if this functionality is considered no longer > desirable/necessary? > > If not, is it anticipated that this functionality could/would be > included in a later kernel? > Hi Mark, In a coffee deprived stupor ;), I responded to this mail in the wrong thread, here: http://lkml.org/lkml/2008/1/18/207 Sorry for the confusion HTH -Greg > Regards, > Mark Hansen > > > -- > 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/ > -- 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/