From owner-freebsd-current@FreeBSD.ORG Mon Oct 28 18:35:24 2013 Return-Path: Delivered-To: freebsd-current@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id CFF43E0 for ; Mon, 28 Oct 2013 18:35:24 +0000 (UTC) (envelope-from freebsd@allanjude.com) Received: from mx1.scaleengine.net (beauharnois2.bhs1.scaleengine.net [142.4.218.15]) by mx1.freebsd.org (Postfix) with ESMTP id ABE00241F for ; Mon, 28 Oct 2013 18:35:24 +0000 (UTC) Received: from [10.1.1.1] (S01060001abad1dea.hm.shawcable.net [50.70.108.129]) (Authenticated sender: allan.jude@scaleengine.com) by mx1.scaleengine.net (Postfix) with ESMTPSA id 9F2A04290B for ; Mon, 28 Oct 2013 18:35:23 +0000 (UTC) Message-ID: <526EAE73.8040406@allanjude.com> Date: Mon, 28 Oct 2013 14:35:31 -0400 From: Allan Jude User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:24.0) Gecko/20100101 Thunderbird/24.0.1 MIME-Version: 1.0 To: freebsd-current@freebsd.org Subject: Re: ZFS txg implementation flaw References: <20131028092844.GA24997@zxy.spb.ru> <0F1D571E-2806-4392-A5EC-BE66A3C92BF7@gmail.com> <20131028181631.GV63359@zxy.spb.ru> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.14 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: Mon, 28 Oct 2013 18:35:24 -0000 On 2013-10-28 14:25, aurfalien wrote: > On Oct 28, 2013, at 11:16 AM, Slawa Olhovchenkov wrote: > >> On Mon, Oct 28, 2013 at 10:45:02AM -0700, aurfalien wrote: >> >>> On Oct 28, 2013, at 2:28 AM, Slawa Olhovchenkov wrote: >>> >>>> I can be wrong. >>>> As I see ZFS cretate seperate thread for earch txg writing. >>>> Also for writing to L2ARC. >>>> As result -- up to several thousands threads created and destoyed per >>>> second. And hundreds thousands page allocations, zeroing, maping >>>> unmaping and freeing per seconds. Very high overhead. >>>> >>>> In systat -vmstat I see totfr up to 600000, prcfr up to 200000. >>>> >>>> Estimated overhead -- 30% of system time. >>>> >>>> Can anybody implement thread and page pool for txg? >>> Would lowering vfs.zfs.txg.timeout be a way to tame or mitigate this? >> vfs.zfs.txg.timeout: 5 >> >> Only x5 lowering (less in real case with burst writing). And more fragmentation on writing and etc. > So leave it default in other words. > > Good to know. > > - aurf > > _______________________________________________ > freebsd-current@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-current > To unsubscribe, send any mail to "freebsd-current-unsubscribe@freebsd.org" The default is the default for a reason, although the original default was 30 -- Allan Jude