From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S267333AbUHECJ4 (ORCPT ); Wed, 4 Aug 2004 22:09:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267350AbUHECJ4 (ORCPT ); Wed, 4 Aug 2004 22:09:56 -0400 Received: from gizmo01ps.bigpond.com ([144.140.71.11]:59365 "HELO gizmo01ps.bigpond.com") by vger.kernel.org with SMTP id S267333AbUHECJx (ORCPT ); Wed, 4 Aug 2004 22:09:53 -0400 Message-ID: <411196EE.9050408@bigpond.net.au> Date: Thu, 05 Aug 2004 12:09:50 +1000 From: Peter Williams User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.4) Gecko/20030624 Netscape/7.1 X-Accept-Language: en-us, en MIME-Version: 1.0 To: Nick Piggin CC: Albert Cahalan , linux-kernel mailing list , kernel@kolivas.org, Andrew Morton OSDL Subject: Re: SCHED_BATCH and SCHED_BATCH numbering References: <1091638227.1232.1750.camel@cube> <41118AAE.7090107@bigpond.net.au> <41118D0C.9090103@yahoo.com.au> In-Reply-To: <41118D0C.9090103@yahoo.com.au> Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Nick Piggin wrote: > Peter Williams wrote: > >> Albert Cahalan wrote: >> >>> Are these going to be numbered consecutively, or might >>> they better be done like the task state? SCHED_FIFO is >>> in fact already treated this way in one place. One might >>> want to test values this way: >>> >>> if(foo & (SCHED_ISO|SCHED_RR|SCHED_FIFO)) ... >>> >>> (leaving aside SCHED_OTHER==0, or just translate >>> that single value for the ABI) >>> >>> I'd like to see these get permenant allocations >>> soon, even if the code doesn't go into the kernel. >>> This is because user-space needs to know the values. >> >> >> >> Excellent idea. The definition of rt_task() could become: >> >> #define rt_task(p) ((p)->policy & (SCHED_RR|SCHED_FIFO)) >> >> instead of the highly dodgy: I probably should have said "slightly" instead of "highly" here but I got carried away. :-) >> >> #define rt_task(p) ((p)->prio < MAX_RT_PRIO) >> > > Nothing wrong with that, is there? It's sloppy logic in that "prio" being less than MAX_RT_PRIO is a consequence of the task being real time not the definition of it. At the moment it is a sufficient condition for identifying a task as real time but that may not always be the case. But, the real issue is, what's the point of having a field, "policy", that IS the definitive indicator of the task's scheduling policy if you don't use it? An rt_task() function/macro defined in terms of the policy field with this suggested numbering scheme should always be correct. At the moment rt_task(p) could be defined as ((p)->policy != SCHED_OTHER) but the addition of SCHED_ISO and SCHED_BATCH would break that. Another option would be (((p)->policy == SCHED_FIFO) || ((p)->policy == SCHED_RR)) but that's a little long winded and (avoiding it) is probably the reason for the current definition. So I stand by my comment that Albert's numbering scheme is an excellent idea. Peter -- Peter Williams pwil3058@bigpond.net.au "Learning, n. The kind of ignorance distinguishing the studious." -- Ambrose Bierce