From owner-svn-src-all@FreeBSD.ORG Wed Oct 31 19:42:41 2012 Return-Path: Delivered-To: svn-src-all@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 730F2FAE; Wed, 31 Oct 2012 19:42:41 +0000 (UTC) (envelope-from jim.harris@gmail.com) Received: from mail-vb0-f54.google.com (mail-vb0-f54.google.com [209.85.212.54]) by mx1.freebsd.org (Postfix) with ESMTP id B37BB8FC12; Wed, 31 Oct 2012 19:42:40 +0000 (UTC) Received: by mail-vb0-f54.google.com with SMTP id l1so2499235vba.13 for ; Wed, 31 Oct 2012 12:42:39 -0700 (PDT) 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:content-type; bh=7OGLfspj0eqogegdBQ/jwKq4W1Fqe/k96yuraK1IcyE=; b=OPq/JZ4OHCN8papvYcIfKLSYDb2ruP+ZbKHpAJdHgc/y6Lohui9+lm4JbsPsJIPJAU uvIu+USjAm9NZFfoqOvNgbxhi9YQ07ojdsOvran/Ot1xeXy5MH3Wj7A4ILzLuUC1j0gV h/NtTCWYBvFcHGX53C4y5ZKOjSN1aCk5J1nimYcmoCrcaxq6JAvxmThw8kbS3ypEYRZ2 o8nt5vnt+aq+TZowYuc5ogMtUyt/9777GEDJe4VYbDj/+d6D669ONao4mTP/58IsxIcZ z7hF7zSeAwEKvUoY744ZkB4/OUdhDz3OAMxntOctmahCTYX83GUZu/j4NtCKZq5/i/8U oRnA== MIME-Version: 1.0 Received: by 10.221.11.15 with SMTP id pc15mr40735674vcb.70.1351712559616; Wed, 31 Oct 2012 12:42:39 -0700 (PDT) Received: by 10.58.225.2 with HTTP; Wed, 31 Oct 2012 12:42:39 -0700 (PDT) In-Reply-To: <20121031193020.GJ3309@server.rulingia.com> References: <201210311807.q9VI7IcX000993@svn.freebsd.org> <1351707964.1120.97.camel@revolution.hippie.lan> <20121031193020.GJ3309@server.rulingia.com> Date: Wed, 31 Oct 2012 12:42:39 -0700 Message-ID: Subject: Re: svn commit: r242402 - in head/sys: kern vm From: Jim Harris To: Peter Jeremy Content-Type: text/plain; charset=ISO-8859-1 X-Content-Filtered-By: Mailman/MimeDel 2.1.14 Cc: Attilio Rao , svn-src-head@freebsd.org, Adrian Chadd , src-committers@freebsd.org, svn-src-all@freebsd.org X-BeenThere: svn-src-all@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: "SVN commit messages for the entire src tree \(except for " user" and " projects" \)" List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 31 Oct 2012 19:42:41 -0000 On Wed, Oct 31, 2012 at 12:30 PM, Peter Jeremy wrote: > On 2012-Oct-31 18:57:37 +0000, Attilio Rao wrote: > >On 10/31/12, Adrian Chadd wrote: > >> Right, but you didn't make it configurable for us embedded peeps who > >> still care about memory usage. > > > >How is this possible without breaking the module/kernel ABI? > > Memory usage may override ABI compatibility in an embedded environment. > > >All that assuming you can actually prove a real performance loss even > >in the new cases. > > The issue with padding on embedded systems is memory utilisation rather > than performance. Agree that for embedded systems, we need to be careful about proliferating this throughout the entire kernel. But for the usages thus far, Attilio is right that they should not affect UP. The ULE and callout changes made very recently are on per-CPU data structures, so for UP, that's padding just one mutex each. For the vpglock->mtx_padalign conversion, this is functionally a nop. vpglock was already doing this padding. -Jim