Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S934544Ab1ETAr6 (ORCPT ); Thu, 19 May 2011 20:47:58 -0400 Received: from mail-fx0-f46.google.com ([209.85.161.46]:64010 "EHLO mail-fx0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933236Ab1ETAr4 convert rfc822-to-8bit (ORCPT ); Thu, 19 May 2011 20:47:56 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=gamma; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type:content-transfer-encoding; b=o6bPSzaoAJEd82yXCmkldlo4+4+huuJSTQALq2TPtWIoHMvXbPVJb6xD+Lfi8dichR fP/E6yUm0JO9PNbV5hSjM8LAfJPtikIsCiT8pQNRf/I5sAONV5eQOyrcQPY0xdVVaf48 8zHhWqhbjPgwx2ZzDCQJszRpTIj+sJVF+JgqE= MIME-Version: 1.0 In-Reply-To: <1305851769.7481.90.camel@pasglop> References: <1305753895-24845-1-git-send-email-ericvh@gmail.com> <1305753895-24845-5-git-send-email-ericvh@gmail.com> <1305851769.7481.90.camel@pasglop> Date: Thu, 19 May 2011 19:47:55 -0500 Message-ID: Subject: Re: [PATCH 5/7] [RFC] force 32-byte aligned kmallocs From: Eric Van Hensbergen To: Benjamin Herrenschmidt Cc: linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, bg-linux@lists.anl-external.org Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 8BIT Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1067 Lines: 26 On Thu, May 19, 2011 at 7:36 PM, Benjamin Herrenschmidt wrote: > On Wed, 2011-05-18 at 16:24 -0500, Eric Van Hensbergen wrote: >> >> -#ifdef CONFIG_NOT_COHERENT_CACHE >> +#if defined(CONFIG_NOT_COHERENT_CACHE) || defined(CONFIG_BGP) >> ?#define ARCH_DMA_MINALIGN ? ?L1_CACHE_BYTES >> ?#endif > > Is DMA cache coherent on BG/P ? That's odd for a 4xx base :-) > My understanding of things (which could be totally wrong) is that the DMA we care about on BG/P (namely the Torus and Collective networks) is coherent at the L2. Of course the change in question is talking about L1_CACHE_BYTES, so my reading of this is that its a sleazy way of getting aligned mallocs that make interactions with the tightly coupled networks easier/more-efficient. I'm open to alternative suggestions. -eric -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/