From owner-freebsd-fs@FreeBSD.ORG Mon Oct 28 21:38:31 2013 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTP id 978AA9FC; Mon, 28 Oct 2013 21:38:31 +0000 (UTC) (envelope-from delphij@delphij.net) Received: from anubis.delphij.net (anubis.delphij.net [64.62.153.212]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 7D64D20E4; Mon, 28 Oct 2013 21:38:31 +0000 (UTC) Received: from zeta.ixsystems.com (unknown [69.198.165.132]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by anubis.delphij.net (Postfix) with ESMTPSA id AF3422A44F; Mon, 28 Oct 2013 14:38:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=simple/simple; d=delphij.net; s=anubis; t=1382996310; bh=O9C7UuDP78lPI+TJ6kI6phwkDDKMfut4Q5OH4eFW57M=; h=Date:From:Reply-To:To:CC:Subject:References:In-Reply-To; b=RU7IcZpomYUQfPJuORtmudu4OwehlrKv6NesTAUvZ67QFrnYaeXfnEzXMHgMMWl5h ibHfpSmf8vJ5RAK9yp9yGdEBLHKI+v3WgPavy/Yqh4fzCkXnUzr0vkTThCQ01v5uSt nikusMECBknDInZzRXWIL3OGNtNeXQOzhVC+ptos= Message-ID: <526ED956.10202@delphij.net> Date: Mon, 28 Oct 2013 14:38:30 -0700 From: Xin Li Organization: The FreeBSD Project MIME-Version: 1.0 To: Slawa Olhovchenkov , Jordan Hubbard Subject: Re: ZFS txg implementation flaw References: <20131028092844.GA24997@zxy.spb.ru> <9A00B135-7D28-47EB-ADB3-E87C38BAC6B6@ixsystems.com> <20131028213204.GX63359@zxy.spb.ru> In-Reply-To: <20131028213204.GX63359@zxy.spb.ru> X-Enigmail-Version: 1.6 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: freebsd-fs@freebsd.org, freebsd-current@freebsd.org X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: d@delphij.net List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 28 Oct 2013 21:38:31 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA512 On 10/28/13 14:32, Slawa Olhovchenkov wrote: > On Mon, Oct 28, 2013 at 02:22:16PM -0700, Jordan Hubbard wrote: > >> >> On Oct 28, 2013, at 2:28 AM, Slawa Olhovchenkov >> wrote: >> >>> 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. >> >> How are you measuring the number of threads being created / >> destroyed? This claim seems erroneous given how the ZFS thread >> pool mechanism actually works (and yes, there are thread pools >> already). >> >> It would be helpful to both see your measurement methodology and >> the workload you are using in your tests. > > Semi-indirect. dtrace -n 'fbt:kernel:vm_object_terminate:entry { > @traces[stack()] = count(); }' > > After some (2-3) seconds > > kernel`vnode_destroy_vobject+0xb9 zfs.ko`zfs_freebsd_reclaim+0x2e > kernel`VOP_RECLAIM_APV+0x78 kernel`vgonel+0x134 > kernel`vnlru_free+0x362 kernel`vnlru_proc+0x61e > kernel`fork_exit+0x11f kernel`0xffffffff80cdbfde 2490 > > I don't have user process created threads nor do fork/exit. This has nothing to do with fork/exit but does suggest that you are running of vnodes. What does sysctl -a | grep vnode say? Cheers, - -- Xin LI https://www.delphij.net/ FreeBSD - The Power to Serve! Live free or die -----BEGIN PGP SIGNATURE----- iQIcBAEBCgAGBQJSbtlWAAoJEJW2GBstM+ns1BgP/iD89HXV3g/c4/GliMG27yB0 WMoWJVDvHmzvRuHBMC6rUIqvyfSaK4EdFDK2jYUIM9qQwWcrSXRXIDBLNE/5MHwl FgcsaBlFaE17bMwzWrZRCzSb1YMxHXmHG5e10YrGUW8TKkGBVtDD6SIMVK8xg6SQ 5HM2HJR8BVaB65z4S1tLxA+VIqHitUZ0/kTME6X1Z+Y/CwS29F+seXk1DlDYNZM3 W3UVTxJnVwf9HhHRvx/kDtPIPeuIz0O/M5cgtbYq78wjG9Zim6a8SWpuxKeduDoT CTllgyEidc+vtDiEiksRsja3ATwynzjLGlNribnMKP2U4KMu9qfVUXDse3wwKKXa +f9Yfzg+fif3r6d/hdlQCtHJhjNlqfjDjCXHHpuTftLU2ONpj9hwKYKOqp6ykmt9 Ok2QziXqBxRMVXJjDAOybv8P1zCAcTpRtvR25bbE7T0M49dvVw51CdAdX8m8nJR+ tX72r+j4BeoNflQWqSsG8P9ao3AuOk6jGgXdtngbbpteyplaVqLragFo8shfUNmY dWaJp46wUq3gaRBSO/4CkzdyWl99eTTOAW4/Zr78LuYT5wN7FL590AAT3Jmc9N4Z edZsR2a8VwluLAVuJNqf9odg7MW03xxjKKf9Wm/I112XtFHDg/dCIrdf4cWc5iuA SvGKci6yZfy5e6hj+ZH5 =aVMu -----END PGP SIGNATURE-----