From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-5.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id B5A63C43441 for ; Wed, 21 Nov 2018 16:57:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F2DC214DA for ; Wed, 21 Nov 2018 16:57:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 7F2DC214DA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=arm.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732083AbeKVDcx (ORCPT ); Wed, 21 Nov 2018 22:32:53 -0500 Received: from foss.arm.com ([217.140.101.70]:55122 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1730417AbeKVDcx (ORCPT ); Wed, 21 Nov 2018 22:32:53 -0500 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 2B57022F8; Wed, 21 Nov 2018 08:57:40 -0800 (PST) Received: from edgewater-inn.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.72.51.249]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id EEFC03F5AF; Wed, 21 Nov 2018 08:57:39 -0800 (PST) Received: by edgewater-inn.cambridge.arm.com (Postfix, from userid 1000) id B29241AE100A; Wed, 21 Nov 2018 16:57:55 +0000 (GMT) Date: Wed, 21 Nov 2018 16:57:55 +0000 From: Will Deacon To: John Garry Cc: joro@8bytes.org, robin.murphy@arm.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, ganapatrao.kulkarni@cavium.com, hch@lst.de, m.szyprowski@samsung.com, linuxarm@huawei.com Subject: Re: [PATCH v3] iommu/dma: Use NUMA aware memory allocations in __iommu_dma_alloc_pages() Message-ID: <20181121165755.GE24883@arm.com> References: <1542812051-178935-1-git-send-email-john.garry@huawei.com> <20181121160718.GB24883@arm.com> <24be0d21-63b1-c88d-fdfd-42575f12634f@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <24be0d21-63b1-c88d-fdfd-42575f12634f@huawei.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Nov 21, 2018 at 04:47:48PM +0000, John Garry wrote: > On 21/11/2018 16:07, Will Deacon wrote: > >On Wed, Nov 21, 2018 at 10:54:10PM +0800, John Garry wrote: > >>From: Ganapatrao Kulkarni > >> > >>Change function __iommu_dma_alloc_pages() to allocate pages for DMA from > >>respective device NUMA node. The ternary operator which would be for > >>alloc_pages_node() is tidied along with this. > >> > >>We also include a change to use kvzalloc() for kzalloc()/vzalloc() > >>combination. > >> > >>Signed-off-by: Ganapatrao Kulkarni > >>[JPG: Added kvzalloc(), drop pages ** being device local, tidied ternary operator] > >>Signed-off-by: John Garry > > > >Weird, you're missing a diffstat here. > > > >Anyway, the patch looks fine to me, but it would be nice if you could > >justify the change with some numbers. Do you actually see an improvement > >from this change? > > > > Hi Will, > > Ah, I missed adding my comments explaining the motivation. It would be > better in the commit log. Anyway, here's the snippet: > > " ... as mentioned in [3], dma_alloc_coherent() uses the locality > information from the device - as in direct DMA - so this patch is just > applying this same policy. > > [3] > https://www.mail-archive.com/linux-kernel@vger.kernel.org/msg1692998.html" Yes, please add to this to the commit log. > I did have some numbers to show improvement in some scenarios when I tested > this a while back which I'll dig out. > > However I would say that some scenarios will improve and the opposite for > others with this change, considering different conditions in which DMA > memory may be used. Well, if you can show that it's useful in some cases and not catastrophic in others, then I think shooting for parity with direct DMA is a reasonable justification for the change. Will