From owner-freebsd-performance@FreeBSD.ORG Fri Oct 31 05:26:42 2014 Return-Path: Delivered-To: freebsd-performance@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id C83AAA77; Fri, 31 Oct 2014 05:26:42 +0000 (UTC) Received: from mail-ig0-x22f.google.com (mail-ig0-x22f.google.com [IPv6:2607:f8b0:4001:c05::22f]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (Client CN "smtp.gmail.com", Issuer "Google Internet Authority G2" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 8D79680C; Fri, 31 Oct 2014 05:26:42 +0000 (UTC) Received: by mail-ig0-f175.google.com with SMTP id h3so349859igd.2 for ; Thu, 30 Oct 2014 22:26:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=5LDxEMhsjEl3cM3hT1UaAicVeDkWisIwgeoAZymw/tg=; b=xo4p+ucn5aaT3BI34m3XNNknxlK2GVYqEh3kxDCQRV3wnLzmSSI6e4o74Rvn2cIcu+ 4m6rp4cf8fmwXKHHbA84LwA3z8TLuf7AAK2CEcAaOuaAyxiYD5lD4R2xXZed0MrvzzHF LHdCtzkDuIpyYkxEmOq8FwVcHQADtQSCAaA0vi6wWa5QKAPyrC7VqX+yd1EgNzr/zQX7 p5ShGu4cejYJoabQysMXYlO81RTxnQraY88iI2HWZOONnpJE5opp4UXQF8LabUJngp6A HgK/xxgN58pjTitUzoGPNoCytXUnC9GAeyX7ol4qctLShkoFK3KlzFFROgnqB559SXn5 Ntuw== X-Received: by 10.107.15.213 with SMTP id 82mr8298975iop.63.1414733201957; Thu, 30 Oct 2014 22:26:41 -0700 (PDT) MIME-Version: 1.0 Received: by 10.107.50.203 with HTTP; Thu, 30 Oct 2014 22:26:21 -0700 (PDT) In-Reply-To: References: <20141028114537.83f9f0a3c730949f453c3819@systemdatarecorder.org> From: Brendan Gregg Date: Thu, 30 Oct 2014 22:26:21 -0700 Message-ID: Subject: Re: pmcstat -z32 -G truncates callgraph to 8 To: Ed Maste Content-Type: text/plain; charset=UTF-8 Cc: Stefan Parvu , freebsd-performance@freebsd.org X-BeenThere: freebsd-performance@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Performance/tuning List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 31 Oct 2014 05:26:42 -0000 G'Day Ed, On Wed, Oct 29, 2014 at 12:40 PM, Ed Maste wrote: > On 28 October 2014 13:38, Brendan Gregg wrote: >> Ah, thanks, I'm on 10.0-STABLE and I have: >> >> kern.hwpmc.callchaindepth: 8 >> >> Glad it's something simple! > > Those are the best kinds of problems to have, although we ought to > make sure this point is covered in the FreeBSD profiling documentation > that we have or create. Yes; at least we have this thread now, which should be searchable. > > Also, do you think that we should bump the compiled-in default up to 32? Yes. When I'm using profiling data, I like full stacks for making flame graphs. For the FreeBSD kernel, 32 frames should usually be enough (I have a flame graph that reaches 24 frames for the kernel, but no more). For user-level, I'd probably need ~100. So making the compiled-in default to 32 would hopefully be sufficient for most kernel profiling, and one would need to bump that up for deep user-level stacks. I guess this would also need PMC_CALLCHAIN_DEPTH_MAX = 128 to work. Brendan