From owner-freebsd-fs@freebsd.org Fri Feb 19 18:51:22 2016 Return-Path: Delivered-To: freebsd-fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 564C1AAD7A1 for ; Fri, 19 Feb 2016 18:51:22 +0000 (UTC) (envelope-from thomasrcurry@gmail.com) Received: from mailman.ysv.freebsd.org (mailman.ysv.freebsd.org [IPv6:2001:1900:2254:206a::50:5]) by mx1.freebsd.org (Postfix) with ESMTP id 385551146 for ; Fri, 19 Feb 2016 18:51:22 +0000 (UTC) (envelope-from thomasrcurry@gmail.com) Received: by mailman.ysv.freebsd.org (Postfix) id 355A6AAD7A0; Fri, 19 Feb 2016 18:51:22 +0000 (UTC) Delivered-To: fs@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id 34EBCAAD79B for ; Fri, 19 Feb 2016 18:51:22 +0000 (UTC) (envelope-from thomasrcurry@gmail.com) Received: from mail-ig0-x22c.google.com (mail-ig0-x22c.google.com [IPv6:2607:f8b0:4001:c05::22c]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 014161145 for ; Fri, 19 Feb 2016 18:51:22 +0000 (UTC) (envelope-from thomasrcurry@gmail.com) Received: by mail-ig0-x22c.google.com with SMTP id y8so45483999igp.0 for ; Fri, 19 Feb 2016 10:51:21 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc; bh=z3q4CZhrPdAZeITCCBjayJj38Sxv+zrqeit9GXCrx8M=; b=baA+/jlWdUyJU06XDs4dGfcjQ2E/OkQx55hOJW2LMGatPN6Dp/s0KFvYFnNrnGEnQV ua7Jk+dcJ1zP7PkASZhl+taH6KrVPGQlVtP/Eub/ENh/jkofZ0gGO+FHOpco3fmob9DW ad78WZit7adrsLj37ApLhvK0hVUudP+VtNgkZNTuNSCr/4HdZsaIjvEtz8LI6SN6zo3W EfP7AnKGSCGh3KM7MoTnRnUdXYHWL1wkRCnZXliERK+rCHTMr588zOGWcz81lwxjnC1p nA4u7C0FjXyas1oylbydW4G4/0qsxaXPAaLxOkcyCFrk7hBz5OaD544yC3WJorQmSoEy Mr/g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:mime-version:in-reply-to:references:date :message-id:subject:from:to:cc; bh=z3q4CZhrPdAZeITCCBjayJj38Sxv+zrqeit9GXCrx8M=; b=Ad35radx02RVhUwYo43TOoN7WmpuOV7JNaTO7tHjDOBYJQCpPZIYh+f/nOs5d8EGzP +tPeMFRTZm2nfJc6dwY9yRc2IBY/47/u43Tontu5Jj+S2x2GXZKMO9YbJiAs8zXz50Aj Dm7q6jS0nD+ElFnfbXAIXYAd3rS/adbtfvT9WOTjds6t5cxSvDxBttZ4NPi8pI9d08Ji oJo8Hl0ZwzYtMl//DPLaj4YIJgmLDPyhpGg9yTs/koMbJDTOZNvW7NFZzlI/ctDYpy1E yz7NAQO++YEmUViCCkePwG3HXiJGgLZqn8kPfhCWIRhxOS55JGj6/00RxCA8zf0JjMSl oDBQ== X-Gm-Message-State: AG10YOTj6wFgpy/RPaxWL2AHOPcX+Cipu7vv894CQOUHlqWQ1PPHRE9FYDYS4Rn3v9Kx06N0w7lAGSDhRXJ71A== MIME-Version: 1.0 X-Received: by 10.50.137.65 with SMTP id qg1mr10532416igb.28.1455907881339; Fri, 19 Feb 2016 10:51:21 -0800 (PST) Received: by 10.107.4.71 with HTTP; Fri, 19 Feb 2016 10:51:21 -0800 (PST) In-Reply-To: <20160219180716.GA46881@mail.michaelwlucas.com> References: <20160219180716.GA46881@mail.michaelwlucas.com> Date: Fri, 19 Feb 2016 13:51:21 -0500 Message-ID: Subject: Re: dtracing ZFS on FreeBSD From: Tom Curry To: "Michael W. Lucas" Cc: fs@freebsd.org Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable X-Content-Filtered-By: Mailman/MimeDel 2.1.20 X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Feb 2016 18:51:22 -0000 On Fri, Feb 19, 2016 at 1:07 PM, Michael W. Lucas wrote: > Hi, > > I'm trying get Adam Leventhal's dtrace script for measuring latency > and number of operations on a pool > (http://dtrace.org/blogs/ahl/2014/08/31/openzfs-tuning/). Asking for > guidance here because it's a filesystem thing and the dtrace list is > dead. > > The script is: > > #pragma D option aggpack > #pragma D option quiet > > fbt::vdev_queue_max_async_writes:entry > { > self->spa =3D args[0]; > } > fbt::vdev_queue_max_async_writes:return > /self->spa && self->spa->spa_name =3D=3D $$1/ > { > @ =3D lquantize(args[1], 0, 30, 1); > } > > tick-1s > { > printa(@); > clear(@); > } > > fbt::vdev_queue_max_async_writes:return > /self->spa/ > { > self->spa =3D 0; > } > > When I run it: > > # dtrace -s q.d zroot > > most lines look like this: > > min .--------------------------------. max | count > < 0 : : >=3D 30 | 0 > dtrace: 15857 dynamic variable drops with non-empty dirty list > > My reading of dtrace discussions says I'm losing data here. I suspect > this is the data I'm actually interested in. > > Sometimes, the scale gets a marker on it. Pardon the weird characters: > > min .--------------------------------. max | count > < 0 : =E2=96=88 : >=3D 30 | 3438 > > > Or there's > > min .--------------------------------. max | count > < 0 : =E2=96=81=E2=96=82=E2=96=83=E2=96=85 = : >=3D 30 | 19172 > > Any thoughts on why? > > Thanks, > =3D=3Dml > > -- > Michael W. Lucas - mwlucas@michaelwlucas.com, Twitter @mwlauthor > http://www.MichaelWLucas.com/, http://blather.MichaelWLucas.com/ > > > For the variable drops you could try increasing the buffer size, I know I ran into this when I was tracing something very noisy and it definitely helped. #pragma D option bufsize=3D1m http://dtrace.org/guide/chp-buf.html