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=-2.3 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 1F470C4BA06 for ; Wed, 26 Feb 2020 03:05:35 +0000 (UTC) Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id E511521744 for ; Wed, 26 Feb 2020 03:05:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=lists.infradead.org header.i=@lists.infradead.org header.b="IzMDNhUK" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org E511521744 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=huawei.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20170209; h=Sender:Content-Type: Content-Transfer-Encoding:Cc:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:Date:Message-ID:From: References:To:Subject:Reply-To:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=wvChzpTsE2jJD/DJP8aOboeiqdXYvHG5VDO5/XL0DL4=; b=IzMDNhUKm55cC2rfbsSGdBSHg nhwoAYbVg2yrZeiZF5dR1arRWOlk7go1i0wDySQsIYmGZGKpuClCzTv+8vhb1dvooTVS2SnCLFbC3 NSiHgoMHN7prW2ty36E36oigEl/p727AEzR0cAuY7KXbRkfLT65ZF0qo53F0YCI1uBVkr+Ts3bKww /mqCM0ZkgO2ayYVd/bYnUkrasBz7Icsq4F8ikCByn5YFGXlDvq+5CDmy0Js1eDdmaYNsV6byBuA7I 4dgY4UKvANNQw/NRjJnbUp80xtPeevIOz/sQSh9kFVqFyLSbUGjZyMFSdJgwb3Ni37dggReDu4pMa J5FDNWF/g==; Received: from localhost ([127.0.0.1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.92.3 #3 (Red Hat Linux)) id 1j6n0w-0004DR-Ca; Wed, 26 Feb 2020 03:05:34 +0000 Received: from szxga06-in.huawei.com ([45.249.212.32] helo=huawei.com) by bombadil.infradead.org with esmtps (Exim 4.92.3 #3 (Red Hat Linux)) id 1j6n0t-0004CT-MO for linux-arm-kernel@lists.infradead.org; Wed, 26 Feb 2020 03:05:33 +0000 Received: from DGGEMS412-HUB.china.huawei.com (unknown [172.30.72.60]) by Forcepoint Email with ESMTP id 782DE46488E95C5DEB79; Wed, 26 Feb 2020 11:05:22 +0800 (CST) Received: from [127.0.0.1] (10.67.101.242) by DGGEMS412-HUB.china.huawei.com (10.3.19.212) with Microsoft SMTP Server id 14.3.439.0; Wed, 26 Feb 2020 11:05:19 +0800 Subject: Re: [PATCH v4 03/26] iommu: Add a page fault handler To: Jean-Philippe Brucker References: <20200224182401.353359-1-jean-philippe@linaro.org> <20200224182401.353359-4-jean-philippe@linaro.org> <20200225092519.GC375953@myrica> From: Xu Zaibo Message-ID: <0c2b29ad-d09a-89db-8540-5909751b1972@huawei.com> Date: Wed, 26 Feb 2020 11:05:19 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:45.0) Gecko/20100101 Thunderbird/45.7.1 MIME-Version: 1.0 In-Reply-To: <20200225092519.GC375953@myrica> X-Originating-IP: [10.67.101.242] X-CFilter-Loop: Reflected X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20200225_190531_903102_7A9CFC9C X-CRM114-Status: GOOD ( 11.73 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: mark.rutland@arm.com, devicetree@vger.kernel.org, kevin.tian@intel.com, will@kernel.org, Jean-Philippe Brucker , linux-pci@vger.kernel.org, linux-mm@kvack.org, iommu@lists.linux-foundation.org, robh+dt@kernel.org, catalin.marinas@arm.com, tj@kernel.org, zhangfei.gao@linaro.org, robin.murphy@arm.com, christian.koenig@amd.com, linux-arm-kernel@lists.infradead.org Content-Transfer-Encoding: 7bit Content-Type: text/plain; charset="us-ascii"; Format="flowed" Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+infradead-linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi, On 2020/2/25 17:25, Jean-Philippe Brucker wrote: > Hi Zaibo, > > On Tue, Feb 25, 2020 at 11:30:05AM +0800, Xu Zaibo wrote: >>> +struct iopf_queue * >>> +iopf_queue_alloc(const char *name, iopf_queue_flush_t flush, void *cookie) >>> +{ >>> + struct iopf_queue *queue; >>> + >>> + queue = kzalloc(sizeof(*queue), GFP_KERNEL); >>> + if (!queue) >>> + return NULL; >>> + >>> + /* >>> + * The WQ is unordered because the low-level handler enqueues faults by >>> + * group. PRI requests within a group have to be ordered, but once >>> + * that's dealt with, the high-level function can handle groups out of >>> + * order. >>> + */ >>> + queue->wq = alloc_workqueue("iopf_queue/%s", WQ_UNBOUND, 0, name); >> Should this workqueue use 'WQ_HIGHPRI | WQ_UNBOUND' or some flags like this >> to decrease the unexpected >> latency of I/O PageFault here? Or maybe, workqueue will show an uncontrolled >> latency, even in a busy system. > I'll investigate the effect of these flags. So far I've only run on > completely idle systems but it would be interesting to add some > workqueue-heavy load in my tests. > I'm not sure, just my concern. Hopefully, Tejun Heo can give us some hints. :) +cc Tejun Heo Cheers, Zaibo . > . > _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel