From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 7499 invoked by alias); 25 Sep 2013 19:32:56 -0000 Mailing-List: contact libc-ports-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: libc-ports-owner@sourceware.org Received: (qmail 7487 invoked by uid 89); 25 Sep 2013 19:32:56 -0000 Received: from mail-ie0-f177.google.com (HELO mail-ie0-f177.google.com) (209.85.223.177) by sourceware.org (qpsmtpd/0.93/v0.84-503-g423c35a) with (AES128-SHA encrypted) ESMTPS; Wed, 25 Sep 2013 19:32:56 +0000 Authentication-Results: sourceware.org; auth=none X-Virus-Found: No X-Spam-SWARE-Status: No, score=-2.5 required=5.0 tests=AWL,BAYES_00,NO_RELAYS autolearn=ham version=3.3.2 X-HELO: mail-ie0-f177.google.com Received: by mail-ie0-f177.google.com with SMTP id qd12so160559ieb.8 for ; Wed, 25 Sep 2013 12:32:43 -0700 (PDT) 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:content-type; bh=//+2AM573i3VRBVeG45je3pZuzkDKojLrRPrNeAoHao=; b=WtkbEGLu51BHi0FmpUEMnnIGtYMABZ9pQnLCiLPsh0QsCFFO//nH7jgQ4fj/Gk5XR2 OnXraTn0XIVGXOtThRyGo+cLSQ72OlOZ/kVBzbsTZwqAw4iGx/pl162Z3F/9PD2HNJXk N9xDjtPk0mRvjHpeV7UabwAc9uCqx9WApvM+T0rYSfpgpY929CI/SHhXpuCDCPccyYzN QJIiMsZ/ncsb9hD+SjRAJBN2BnQEDTO1oQloVSzkg8hc1SoYK3oIkMLkiTXNPsU1sqz5 CSorzb+/GCb3b1+vOXYGnSIUzwSmT5p6vBMOz1CKzT9N00hEcqzIwS4G9+spWjpyHzSd I5YQ== X-Gm-Message-State: ALoCoQm6WxHYML7vUZyr12SWPXnSWvUkmR/kzuhkHpMcPfludABWby3rql/t4aTR7Y6+1ncAsIud MIME-Version: 1.0 X-Received: by 10.42.46.80 with SMTP id j16mr2779780icf.94.1380137563736; Wed, 25 Sep 2013 12:32:43 -0700 (PDT) Received: by 10.64.20.52 with HTTP; Wed, 25 Sep 2013 12:32:43 -0700 (PDT) In-Reply-To: <5243165F.804@redhat.com> References: <5242A79D.1030709@linaro.org> <52430AA4.70703@redhat.com> <5243165F.804@redhat.com> Date: Wed, 25 Sep 2013 19:32:00 -0000 Message-ID: Subject: Re: [PATCH] ARM: Add pointer guard support. From: Will Newton To: Andrew Haley Cc: "Carlos O'Donell" , "libc-ports@sourceware.org" , Patch Tracking Content-Type: text/plain; charset=ISO-8859-1 X-IsSubscribed: yes X-SW-Source: 2013-09/txt/msg00137.txt.bz2 On 25 September 2013 17:59, Andrew Haley wrote: > On 09/25/2013 05:23 PM, Will Newton wrote: >> From a back of the envelope calculation the cost of accessing TLS is >> one cycle faster than accessing a global in best case (e.g. >> Cortex-A15) > > Why is TLS so fast on Cortex-A15? I don't have exact numbers but the mrc instruction used to load the thread pointer into a general purpose register has very variable timings depending on which core you have. A15 is the fastest of the Cortex-A cores in this regard. -- Will Newton Toolchain Working Group, Linaro