From owner-freebsd-current@FreeBSD.ORG Fri Oct 5 01:32:16 2007 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 8F27316A419 for ; Fri, 5 Oct 2007 01:32:16 +0000 (UTC) (envelope-from deischen@freebsd.org) Received: from mail.netplex.net (mail.netplex.net [204.213.176.10]) by mx1.freebsd.org (Postfix) with ESMTP id 5461913C48D for ; Fri, 5 Oct 2007 01:32:16 +0000 (UTC) (envelope-from deischen@freebsd.org) Received: from sea.ntplx.net (sea.ntplx.net [204.213.176.11]) by mail.netplex.net (8.14.1/8.14.1/NETPLEX) with ESMTP id l951W7R2027630; Thu, 4 Oct 2007 21:32:07 -0400 (EDT) X-Virus-Scanned: by AMaViS and Clam AntiVirus (mail.netplex.net) X-Greylist: Message whitelisted by DRAC access database, not delayed by milter-greylist-3.0 (mail.netplex.net [204.213.176.10]); Thu, 04 Oct 2007 21:32:07 -0400 (EDT) Date: Thu, 4 Oct 2007 21:32:07 -0400 (EDT) From: Daniel Eischen X-X-Sender: eischen@sea.ntplx.net To: Jeff Roberson In-Reply-To: <20071004182539.H912@10.0.0.1> Message-ID: References: <20071002165007.D587@10.0.0.1> <20071003110727.411aa2de@pleiades.nextvenue.com> <2155.10.202.77.103.1191443576.squirrel@webmail.superhero.nl> <20071004174044.E912@10.0.0.1> <20071004182539.H912@10.0.0.1> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-current@freebsd.org, "Gelsema, P \(Patrick\) - FreeBSD" Subject: Re: ULE/yielding patch for testing. X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Daniel Eischen List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 05 Oct 2007 01:32:16 -0000 On Thu, 4 Oct 2007, Jeff Roberson wrote: > On Thu, 4 Oct 2007, Daniel Eischen wrote: > >> On Thu, 4 Oct 2007, Jeff Roberson wrote: >> >>> >>> I believe I have fixed this bug in the enclosed patch. It is rooted from >>> /usr/src/sys so you should cd there to apply it. >> >> This doesn't break realtime threads doing a sched_yield() does >> it? I couldn't easily see how the priority gets set back into >> the realtime class range. But then, maybe I'm a dummy ;-) > > Well the historical behavior was for sched_yield() to not adjust priorities. > It just requeues at the back of the queue for that priority. Xu changed this > in 7.0 but he didn't answer my mail as to why. We have a yield() call that > does drop to the max timeshare priority, however, it doesn't seem to have a > man page. > > The code removed was this: > > - if (td->td_pri_class == PRI_TIMESHARE) > - sched_prio(td, PRI_MAX_TIMESHARE); > > > So it really only effected timesharing threads. As I read the change, now it affects real-time (which is the desired behavior since it is a POSIX real-time extension). But it should have POSIX-defined behavior, which is to requeue at the back of the queue for that priority. -- DE