From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753897Ab3J0TBw (ORCPT ); Sun, 27 Oct 2013 15:01:52 -0400 Received: from mail.skyhub.de ([78.46.96.112]:50872 "EHLO mail.skyhub.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753427Ab3J0TBv (ORCPT ); Sun, 27 Oct 2013 15:01:51 -0400 Date: Sun, 27 Oct 2013 20:01:48 +0100 From: Borislav Petkov To: Andreas Werner Cc: tglx@linutronix.de, mingo@redhat.com, hpa@zytor.com, x86@kernel.org, dave@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH] X86: MM: Add PAT Type write-through in combination with mtrr Message-ID: <20131027190148.GD21868@pd.tnic> References: <1382878525-3410-1-git-send-email-wernerandy@gmx.de> <20131027133401.GB24817@pd.tnic> <20131027165159.GD1617@thinkpad.fritz.box> <20131027173131.GC21868@pd.tnic> <20131027175608.GA1340@thinkpad.fritz.box> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20131027175608.GA1340@thinkpad.fritz.box> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Oct 27, 2013 at 06:56:08PM +0100, Andreas Werner wrote: > Transmit Buffers WC (only write to that buffer) > i have PICe bursts on my tracer. For that you can do ioremap_wc(). > Receive Buffers WT (only read to that buffer). I use > clflush_cache_range before reading from that adresses and i have PCIe > bursts on my tracer. That one I don't understand - why would you need a WT buffer? It only caches reads but you will read from it only once after it has been received. Why pollute the cache? IOW, you probably could use a WC buffer here too, as it would combine the writes coming from the FPGA. Btw, there's also mtrr_add(..., MTRR_TYPE_WRTHROUGH, ) if you must use a WT thing. Have you tried that? > With UC memory there are no PCIe bursts and my bandwidth is very slow. Right. -- Regards/Gruss, Boris. Sent from a fat crate under my desk. Formatting is fine. --