From owner-freebsd-current@FreeBSD.ORG Sat Aug 28 09:03:56 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 5479F1065694; Sat, 28 Aug 2010 09:03:56 +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 044478FC14; Sat, 28 Aug 2010 09:03:55 +0000 (UTC) Received: by iwn36 with SMTP id 36so3827916iwn.13 for ; Sat, 28 Aug 2010 02:03:55 -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=jFLv9I3QR74RIUEzQf6j7AxtIOZ6YKQJ8Hf6xi7efWw=; b=xEidw9RtGD5i018+rzzDaTL7gKDRJ57MPhDtkqqdNuzvBsBFE5aZfZxE5YG9fjGWrm Kj22JxmsB1U6gFzZu/Ii/R65BampmZcHFCyBY5uoJgDu3Frr/xsHi2O2VzPATIvj+yNd 43jx4TDeknLPfpXgMsC5lhHpne6E5Q+vL4WgM= 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=RdeT43Td55tNL9chQD6tbIEPrlIFX2PRttAbXLQyd52hPiBk9t1xvZv9lxYErcpRtc bWGpbjW3Q2WFdQreKYbyeYEzRbxVWBGkYRMll3fgkewqMlBkfHzDQTEjX+n7tivy48Md 54/LPmHgLMW2pBhKpf+RWWC85ppcjbPXHFELA= Received: by 10.231.11.71 with SMTP id s7mr2447534ibs.85.1282986225621; Sat, 28 Aug 2010 02:03:45 -0700 (PDT) Received: from centel.dataix.local ([99.181.137.20]) by mx.google.com with ESMTPS id n20sm4670291ibe.17.2010.08.28.02.03.43 (version=SSLv3 cipher=RC4-MD5); Sat, 28 Aug 2010 02:03:44 -0700 (PDT) Sender: "J. Hellenthal" Message-ID: <4C78D0EE.6040708@DataIX.net> Date: Sat, 28 Aug 2010 05:03:42 -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: Andriy Gapon References: <4C713EF5.8080402@FreeBSD.org> <4C714FC0.90005@FreeBSD.org> <20100828081917.ee931f7f.nork@FreeBSD.org> <4C78655C.3010200@DataIX.net> <4C78C6C3.1010005@icyb.net.ua> In-Reply-To: <4C78C6C3.1010005@icyb.net.ua> 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 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: Sat, 28 Aug 2010 09:03:56 -0000 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. Regards, -- jhell,v