From owner-freebsd-hackers Sun Sep 23 14:30: 6 2001 Delivered-To: freebsd-hackers@freebsd.org Received: from InterJet.elischer.org (c421509-a.pinol1.sfba.home.com [24.7.86.9]) by hub.freebsd.org (Postfix) with ESMTP id 8E6E437B407 for ; Sun, 23 Sep 2001 14:29:55 -0700 (PDT) Received: from elischer.org (InterJet.elischer.org [192.168.1.1]) by InterJet.elischer.org (8.9.1a/8.9.1) with ESMTP id PAA46997; Sun, 23 Sep 2001 15:14:13 -0700 (PDT) Message-ID: <3BAE5283.C7B434CF@elischer.org> Date: Sun, 23 Sep 2001 14:22:11 -0700 From: Julian Elischer X-Mailer: Mozilla 4.7 [en] (X11; U; FreeBSD 5.0-CURRENT i386) X-Accept-Language: en, hu MIME-Version: 1.0 To: Matt Dillon Cc: Poul-Henning Kamp , David Greenman , Seigo Tanimura , bright@wintelcom.net, hackers@FreeBSD.ORG Subject: Re: Conclusions on... was Re: More on the cache_purgeleafdirs() routine References: <1620.1001272770@critter> <200109232019.f8NKJZL88354@earth.backplane.com> Content-Type: text/plain; charset=iso-8859-2 Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG Matt Dillon wrote: > > :Block input operations is the one notable exception and it tells a > :very interesting story: Matts patch results in a 4% increase, but > :combined with vmdirioenable it results in a 21.5% decrease. > : > :That's pretty darn significant: one out of every five I/O have > :been saved. Notice that both the user and system times increased.. if there had been another parallel task, the overall system throughout may have decreased.. I'm not saying this is wrong, just that we should look at other workloads too. no point in optimising the system for compiling itself.. that's not really a real-world task.. lmost noo-one buys a freeBSD box so that they can compile freeBS.. they usually have other plans for what they want out of it... (of course this may effect other tasks in an even more positive way, but we should know that..) > : > :The reason it has not manifested itself in the "real" number is > :probably the high degree of parallelism in the task which practically > :ensures that the CPU will not go idle. > : > :I suggest we let Matt's patch depend on the vmiodirenable sysctl > :and change the default for that. > : > :If there are no bad side effects found in the next couple of months, > :then kill the sysctl and lets be done with it. > : > :Poul-Henning > > Very interesting! I agree completely. I will instrument the code > to make the namei cache check conditional on vmiodirenable. I will > also add a sysctl to change the check condition to test for leaf > directories or not (closer to what Seigo's code accomplished) so we can > test for differences there. If we can get that 4% down the code will > be more acceptable. > > The results make a lot of sense, especially if the machine has sufficient > memory to cache most of the source tree. Increasing the number of > vnode reclaims will increase I/O on directories, especially for something > like a buildworld which is doing major path expansions up the wazoo. > Turning on vmiodirenable in a buildworld situation will decrease I/O > significantly. > > -Matt > > To Unsubscribe: send mail to majordomo@FreeBSD.org > with "unsubscribe freebsd-hackers" in the body of the message -- +------------------------------------+ ______ _ __ | __--_|\ Julian Elischer | \ U \/ / hard at work in | / \ julian@elischer.org +------>x USA \ a very strange | ( OZ ) \___ ___ | country ! +- X_.---._/ presently in San Francisco \_/ \\ v To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message