From owner-freebsd-current@FreeBSD.ORG Sun Aug 29 09:38:10 2010 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 9F3B710656A9; Sun, 29 Aug 2010 09:38:10 +0000 (UTC) (envelope-from jhellenthal@gmail.com) Received: from mail-iw0-f182.google.com (mail-iw0-f182.google.com [209.85.214.182]) by mx1.freebsd.org (Postfix) with ESMTP id 0FE8E8FC0C; Sun, 29 Aug 2010 09:38:10 +0000 (UTC) Received: by iwn36 with SMTP id 36so4546519iwn.13 for ; Sun, 29 Aug 2010 02:38:09 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=domainkey-signature:received:received:sender:message-id:date:from :user-agent:mime-version:to:cc:subject:references:in-reply-to :x-enigmail-version:content-type:content-transfer-encoding; bh=2TY+eZ7PF4rLM38QbmJkwdY6fkjgxDNF6nxgCSK9m5E=; b=tdbjlkGwr92usBzV4QkQpRzHQRcKFmidehXFfzBiDo8/hFXf77LEkMGC4gmXY3IPu4 XpTyaoJh//2y8YiTfKCaR6XzMsvjFV88uXfGDMxPqOucpmYnsxzFbA+0bRsplq5kTkGj 1n6J6jNrcEU9NiaiU/oDcSmidCyNjZxq918jg= DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=sender:message-id:date:from:user-agent:mime-version:to:cc:subject :references:in-reply-to:x-enigmail-version:content-type :content-transfer-encoding; b=FZ423Y2zUwD21U5eYGnh5YwBhYUcZFJCuu8T7K3u4XxoKgMBBtDZGcZfD7RhQj1vdI NpfHXz0O+sPbMjrcku6q2Ul142O/v/Z01uznd+X+ZAS1sc5yvpp2kfPsmE14UlcshsoR zbk3Qo2v6QGEquQirK4h9CVU6LNB8TO5Q3rbI= Received: by 10.231.184.168 with SMTP id ck40mr3293412ibb.174.1283074689586; Sun, 29 Aug 2010 02:38:09 -0700 (PDT) Received: from centel.dataix.local ([99.181.137.20]) by mx.google.com with ESMTPS id n20sm5974354ibe.11.2010.08.29.02.38.07 (version=SSLv3 cipher=RC4-MD5); Sun, 29 Aug 2010 02:38:07 -0700 (PDT) Sender: "J. Hellenthal" Message-ID: <4C7A2A7D.5040007@DataIX.net> Date: Sun, 29 Aug 2010 05:38:05 -0400 From: jhell User-Agent: Mozilla/5.0 (X11; U; FreeBSD i386; en-US; rv:1.9.2.8) Gecko/20100806 Lightning/1.0b1 Thunderbird MIME-Version: 1.0 To: Pawel Jakub Dawidek References: <4C713EF5.8080402@FreeBSD.org> <4C714FC0.90005@FreeBSD.org> <20100828081917.ee931f7f.nork@FreeBSD.org> <4C78655C.3010200@DataIX.net> <4C78C6C3.1010005@icyb.net.ua> <4C78D0EE.6040708@DataIX.net> <20100828092602.GG2077@garage.freebsd.pl> In-Reply-To: <20100828092602.GG2077@garage.freebsd.pl> X-Enigmail-Version: 1.1.2 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: freebsd-current@freebsd.org, Artem Belevich , Martin Matuska , Andriy Gapon Subject: Re: [CFT] Improved ZFS metaslab code (faster write speed) X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 29 Aug 2010 09:38:10 -0000 On 08/28/2010 05:26, Pawel Jakub Dawidek wrote: > On Sat, Aug 28, 2010 at 05:03:42AM -0400, jhell wrote: >> On 08/28/2010 04:20, Andriy Gapon wrote: >>> on 28/08/2010 04:24 jhell said the following: >>>> The modified patch from avg@ (portion patch) is: >>>> >>>> #ifdef _KERNEL >>>> if (arc_reclaim_needed()) { >>>> needfree = 0; >>>> wakeup(&needfree); >>>> } >>>> #endif >>>> >>>> I still moved that down to below _KERNEL for the obvious reasons. But >>>> when I was using the original patch with if (needfree) I noticed a >>>> performance degradation after ~12 hours of use with and without UMA >>>> turned on. So far with ~48 hours of testing with the top half of that >>>> being with the above change, I have not seen more degradation of >>> >>> This is quite unexpected. >>> needfree should be checked as the very first thing in arc_reclaim_needed() >>> [unless you have patched it locally]. So if needfree is 1 then >>> arc_reclaim_needed() should also return 1. But the converse is not true, >>> arc_reclaim_needed() may return 1 even if needfree is zero. >>> >>> So if your testing results are conclusive then it must mean that some extra >>> wakeups on needfree are needed. I.e. needfree is zero, so there shouldn't be >>> anything waiting on it (see arc_lowmem) and no notification should be needed, >>> but issuing somehow does make difference, >>> Hmm... >>> >> >> I will look further into this and see if I can throw a counter around it >> or some printf's so I can at least log what its doing in both instances. >> >> I thought the very same thing you said above when I saw your patch for >> that and was astounded at the results that were returned from it. So in >> short testing I reverted it back quickly to see if that was the cause of >> the problem and sure enough everything resumed to the way it was before. >> >> Anyway thanks for the reply. I will get back to you if I see anything >> cool arise from this. > > Could you include the following patch to your testing: > > http://people.freebsd.org/~pjd/patches/arc.c.9.patch > Sure thing. Adding it now. -- jhell,v