From owner-freebsd-mips@FreeBSD.ORG Mon Nov 5 18:13:32 2012 Return-Path: Delivered-To: freebsd-mips@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 164885E3 for ; Mon, 5 Nov 2012 18:13:32 +0000 (UTC) (envelope-from lists@eitanadler.com) Received: from mail-lb0-f182.google.com (mail-lb0-f182.google.com [209.85.217.182]) by mx1.freebsd.org (Postfix) with ESMTP id 7455C8FC12 for ; Mon, 5 Nov 2012 18:13:29 +0000 (UTC) Received: by mail-lb0-f182.google.com with SMTP id b5so5521487lbd.13 for ; Mon, 05 Nov 2012 10:13:28 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=eitanadler.com; s=0xdeadbeef; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type; bh=YlBsAeYiv6oEYI5KEsvRm5+j3KWZTz3sYMRE5qDL/Ak=; b=DHKifR+d4DvNJj//+IXAQMbbEb7s8KgVtOnhy/SwoLb36XrOmIeDywDW+BFPxkLyWY rrz2X4Q3xWBCkeKuB2bFcRMlJOmOeqIqsQE3AUBCtLKl3upkL/ZNj0IMyqVIWAE1RyKc oHWlBBb+zyorDbwTTRgG2L1x54u8m0M3sILHM= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20120113; h=mime-version:in-reply-to:references:from:date:message-id:subject:to :cc:content-type:x-gm-message-state; bh=YlBsAeYiv6oEYI5KEsvRm5+j3KWZTz3sYMRE5qDL/Ak=; b=dQoc/Rq8eyjbsxFh5iz4/L2AtQJnLHLYAmibrUtu4Zu2Fw3qJYklnOXcc8sy98sus0 A+Ap/BEf/MlWLHwYT3NLZ74YHrFBuRp9uKyLSgmWqeTWwa0SUpyZBuOCAmUaMdztit80 UuPK6G8GoH4/xDYBSY5yLf+DfKokO06UwFeblJkFZX8KycBtjTYrqmsX+I22oe8QO+AJ uyeCOKa/vA7H/QbW0lJpkR5arB8d0pGGDnldevmzr92aPg2/87v0o8IQHPS+dMK2lmrh OPvMFJ60uLz1C3UTCnzO+aaRelXqYE6kyPaqTmZrcbC3zItu98H6hdvFZJ55m253pguS MQCw== Received: by 10.152.102.234 with SMTP id fr10mr10016855lab.28.1352139208012; Mon, 05 Nov 2012 10:13:28 -0800 (PST) MIME-Version: 1.0 Received: by 10.112.25.166 with HTTP; Mon, 5 Nov 2012 10:12:57 -0800 (PST) In-Reply-To: <1352138944.1120.187.camel@revolution.hippie.lan> References: <201211041828.qA4ISomC076058@pdx.rh.CN85.ChatUSA.com> <1352137087.1120.180.camel@revolution.hippie.lan> <1352138944.1120.187.camel@revolution.hippie.lan> From: Eitan Adler Date: Mon, 5 Nov 2012 13:12:57 -0500 Message-ID: Subject: Re: CACHE_LINE_SIZE macro. To: Ian Lepore Content-Type: text/plain; charset=UTF-8 X-Gm-Message-State: ALoCoQkk/Czm/lfIIWjXkyTp/eXosMw3Z4L3DoOYo7P0XaZgCRHYTkwoJaZp2EGCbynnEnRn8L0a Cc: "Rodney W. Grimes" , Juli Mallett , "freebsd-mips@FreeBSD.org" X-BeenThere: freebsd-mips@freebsd.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: Porting FreeBSD to MIPS List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 05 Nov 2012 18:13:32 -0000 On 5 November 2012 13:09, Ian Lepore wrote: > The other thing that bugs me is that cache is a scarce resource on our > wimpy little platforms, and padding just ensures that we use it even > less effectively in the UP case. It seems like it's more likely to kill > performance than improve it, because one would expect that when a lock > is embedded in a structure, there's going to be access to other data > nearby once the lock is acquired. This is another reason to encourage the separation between the real cache line size and the lock padding version. On low cache-size environments the latter could be tuned to not matter. -- Eitan Adler