From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758861Ab3IBRye (ORCPT ); Mon, 2 Sep 2013 13:54:34 -0400 Received: from smtp02.citrix.com ([66.165.176.63]:43613 "EHLO SMTP02.CITRIX.COM" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756329Ab3IBRyd (ORCPT ); Mon, 2 Sep 2013 13:54:33 -0400 X-IronPort-AV: E=Sophos;i="4.89,1008,1367971200"; d="scan'208";a="47388520" Message-ID: <5224D0D6.40908@citrix.com> Date: Mon, 2 Sep 2013 18:54:30 +0100 From: Zoltan Kiss User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130804 Thunderbird/17.0.8 MIME-Version: 1.0 To: Konrad Rzeszutek Wilk CC: Jeremy Fitzhardinge , Steven Rostedt , Frederic Weisbecker , Ingo Molnar , , , Subject: Re: [PATCH] tracing/events: Add bounce tracing to swiotbl-xen References: <1377208048-8963-1-git-send-email-zoltan.kiss@citrix.com> <20130823125533.GC14306@konrad-lan.dumpdata.com> In-Reply-To: <20130823125533.GC14306@konrad-lan.dumpdata.com> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.80.2.133] X-DLP: MIA2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 23/08/13 13:55, Konrad Rzeszutek Wilk wrote: > On Thu, Aug 22, 2013 at 10:47:28PM +0100, Zoltan Kiss wrote: >> Ftrace is currently not able to detect when SWIOTLB has to do double buffering >> under Xen. You can only see it indirectly in function_graph, when >> xen_swiotlb_map_page() doesn't stop after range_straddles_page_boundary(), but >> calls spinlock functions, memcpy() and xen_phys_to_bus() as well. This patch >> introduces the swiotlb-xen:bounced event, which also prints out the following >> informations to help you find out why bouncing happened: >> >> dev_name: 0000:08:00.0 dma_mask=ffffffffffffffff dev_addr=9149f000 size=32768 >> swiotlb_force=0 >> >> If (dev_addr + size + 1) > dma_mask, the buffer is out of the device's DMA >> range. If swiotlb_force == 1, you should really change the kernel parameters. >> Otherwise, the buffer is not contiguous in mfn space. > > Could this be in the lib/swiotlb.c instead? You mean instead of drivers/xen/swiotlb-xen.c ? This is a Xen SWIOTLB specific thing, it will hit exactly at the point when double buffering becomes sure - under Xen. But I can rename the tracer and call trace_bounced in swiotlb_map_page as well, so it can be used for normal SWIOTLB bounce tracing as well. Is it OK for you? Regards, Zoli