From owner-cvs-src@FreeBSD.ORG Mon Nov 10 21:22:05 2003 Return-Path: Delivered-To: cvs-src@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id EF0B616A4D0; Mon, 10 Nov 2003 21:22:05 -0800 (PST) Received: from sohgo.tanimura.dyndns.org (IP1A0514.kng.mesh.ad.jp [211.13.103.134]) by mx1.FreeBSD.org (Postfix) with ESMTP id 71F2B44008; Mon, 10 Nov 2003 21:22:00 -0800 (PST) (envelope-from tanimura@tanimura.dyndns.org) Received: from sohgo.tanimura.dyndns.org (localhost [IPv6:::1]) ESMTP id hAB5Lvd0041124 ; Tue, 11 Nov 2003 14:21:57 +0900 (JST) Received: (from uucp@localhost) (8.12.9/3.7W-submit-carrots-Tokyu-Meguro) with UUCP id hAB5LuZ5041123 ; Tue, 11 Nov 2003 14:21:56 +0900 (JST) Received: from urban.nkth.tanimura.dyndns.org (localhost [IPv6:::1]) with ESMTP id hAB5JgFX008891 ; Tue, 11 Nov 2003 14:19:42 +0900 (JST) Message-Id: <200311110519.hAB5JgFX008891@urban> Date: Tue, 11 Nov 2003 14:19:42 +0900 From: Seigo Tanimura To: Bruce Evans In-Reply-To: <20031111040413.V717@gamplex.bde.org> References: <20031110180540.P2148@gamplex.bde.org> <200311101217.hAACH9FZ001752@urban> <20031111040413.V717@gamplex.bde.org> User-Agent: Wanderlust/2.10.1 (Watching The Wheels) SEMI/1.14.5 (Awara-Onsen) FLIM/1.14.5 (Demachiyanagi) APEL/10.6 MULE XEmacs/21.4 (patch 13) (Rational FORTRAN) (i386--freebsd) Organization: My Home MIME-Version: 1.0 (generated by SEMI 1.14.5 - "Awara-Onsen") Content-Type: text/plain; charset=US-ASCII cc: cvs-src@freebsd.org cc: Seigo Tanimura cc: src-committers@freebsd.org cc: cvs-all@freebsd.org cc: John Baldwin Subject: Re: cvs commit: src/sys/cam/scsi scsi_target.c src/sys/coda coda_psdev.c src/sys/dev/aac aac.c src/sys/dev/bktr bktr_core.c src/sys/dev/firewire firewire.c src/sys/dev/kbd kbd.c src/sys/dev/nmdm nmdm. X-BeenThere: cvs-src@freebsd.org X-Mailman-Version: 2.1.1 Precedence: list List-Id: CVS commit messages for the src tree List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 11 Nov 2003 05:22:06 -0000 On Tue, 11 Nov 2003 04:16:15 +1100 (EST), Bruce Evans said: bde> On Mon, 10 Nov 2003, Seigo Tanimura wrote: >> On Mon, 10 Nov 2003 18:14:14 +1100 (EST), >> Bruce Evans said: >> ... bde> set the thread priority using that. So this changes is needed to get the bde> same behaviour as using tsleep(). However, I think that behaviour is not bde> quite right -- if the thread is a user thread then it waking it up is only bde> urgent if it needs to do some urgent things in kernel mode on wakeup. It bde> should not return to user mode until its user priority permits its bde> scheduling. However2, we still have the bugfeature that user threads keep bde> the kernel priority that they wake up at all the way back to user mode, bde> and this may be necessary for interactivity. >> >> I could implement priority bumping in selwakeuppri(), but I thought it >> would be troublesome to tweak struct cv outside kern_condvar.c. >> >> In case of select(2) et. al., selecting threads waken up repolls file >> descriptors. As it is a in-kernel work, those threads should remain >> at in-kernel priorities until polling succeeds, aren't they? bde> I think there is no need for elevated kernel priority in select() if bde> threads drop back to their normal user priority on return to user mode, bde> since nothing (?) except the user process is affected by the results bde> of select() (unlike for some i/o operations). Note that the priority That would hold if a thread waken up went straightly back to user mode. bde> is not elevated at the start of select(), so processes can be preempted bde> there now that we have a semi-preempive kernel. Why should the bde> completion of select() be different if the thread needed to sleep? bde> Any increase in priority should be because the thread slept for a while bde> and not arbitrary. We may need some tricks to protect all of the file descriptors being polled in kern_select(). -- Seigo Tanimura