From owner-freebsd-stable@FreeBSD.ORG Wed Aug 15 18:17:26 2007 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 946F016A4E0 for ; Wed, 15 Aug 2007 18:17:26 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.freebsd.org (Postfix) with ESMTP id 2CC3713C4CB for ; Wed, 15 Aug 2007 18:17:26 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from phobos.samsco.home (phobos.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.13.8/8.13.8) with ESMTP id l7FIHMnI010377; Wed, 15 Aug 2007 12:17:22 -0600 (MDT) (envelope-from scottl@samsco.org) Message-ID: <46C3432F.709@samsco.org> Date: Wed, 15 Aug 2007 12:17:19 -0600 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.6) Gecko/20070802 SeaMonkey/1.1.4 MIME-Version: 1.0 To: Kris Kennaway References: <000b01c7df5f$0ee4eec0$0c00a8c0@Artem> <20070815174218.GB71910@rot26.obsecurity.org> In-Reply-To: <20070815174218.GB71910@rot26.obsecurity.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (pooker.samsco.org [168.103.85.57]); Wed, 15 Aug 2007 12:17:22 -0600 (MDT) X-Spam-Status: No, score=-1.4 required=5.5 tests=ALL_TRUSTED autolearn=failed version=3.1.8 X-Spam-Checker-Version: SpamAssassin 3.1.8 (2007-02-13) on pooker.samsco.org Cc: Artem Kuchin , freebsd-stable@freebsd.org Subject: Re: twa is giant locked in 7-Current or everywhere? X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 15 Aug 2007 18:17:26 -0000 Kris Kennaway wrote: > On Wed, Aug 15, 2007 at 09:09:33PM +0400, Artem Kuchin wrote: >> Hi! >> >> When i installed twas driver on 6.2-STABLE it said >> [FAST] >> >> i presumed that it measn that twa is giant-lock free. >> >> Now, after installing 7-CURRENT i see >> >> Aug 15 17:00:02 omni3 kernel: 3ware device driver for 9000 series storage >> controllers, version: 3.70.03.007 >> Aug 15 17:00:02 omni3 kernel: twa0: <3ware 9000 series Storage Controller> >> port 0x3000-0x30ff mem 0x88000000-0x89ffffff,0x8a200000-0x8a200fff irq 16 >> at devic >> Aug 15 17:00:02 omni3 kernel: twa0: [GIANT-LOCKED] >> Aug 15 17:00:02 omni3 kernel: twa0: [ITHREAD] >> >> >> So, it says GIANT-LOCKED and then ITHREAD. >> >> Apparently, i have no real understaning what those words mean. >> COuld anyone explain the meaning of >> >> FAST >> ITHREAD >> >> Giant-locked is self explanatory and.. bad. > > I think 6.x doesn't display the GIANT-LOCKED messages because users > were freaking out too much after they were added at an earlier point > in 6.x development ("Q: why is this driver suddenly giant locked?" "A: > It's always been giant locked, now this fact is displayed as a note to > developers."). > > While it's true that a non-giant locked driver would be better, it's > not as bad as you might think because almost nothing else requires > giant for most workloads thesedays (see > http://wiki.freebsd.org/SMPTODO), so in those workloads performance > will not be worse because of it. If you are really bothered by this > you can enable mutex profiling to check how much of a problem it is > for you. > Just to set the facts straight, the TWA driver has always been covered by Giant, as I explained in another part of this thread. The indication was just hidden because it used an INTR_FAST handler. As for performance, having Giant-free drivers is still highly important. Not having to compete with the tty subsystem or the USB stack is very important. My recent change to make ATAPI-CAM Giant-free made CD burning a lot more pleasant for people. Scott