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=-0.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 03705C3A5A0 for ; Mon, 19 Aug 2019 20:52:08 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id C607622CEB for ; Mon, 19 Aug 2019 20:52:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728484AbfHSUwG (ORCPT ); Mon, 19 Aug 2019 16:52:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33602 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727971AbfHSUwG (ORCPT ); Mon, 19 Aug 2019 16:52:06 -0400 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id DE54111A06; Mon, 19 Aug 2019 20:51:59 +0000 (UTC) Received: from x1.home (ovpn-116-99.phx2.redhat.com [10.3.116.99]) by smtp.corp.redhat.com (Postfix) with ESMTP id 31BEA52CE; Mon, 19 Aug 2019 20:51:55 +0000 (UTC) Date: Mon, 19 Aug 2019 14:51:50 -0600 From: Alex Williamson To: Ben Luo Cc: tglx@linutronix.de, linux-kernel@vger.kernel.org, tao.ma@linux.alibaba.com, gerry@linux.alibaba.com, nanhai.zou@linux.alibaba.com, linyunsheng@huawei.com Subject: Re: [PATCH v3 0/3] genirq/vfio: Introduce update_irq_devid and optimize VFIO irq ops Message-ID: <20190819145150.2d30669b@x1.home> In-Reply-To: References: Organization: Red Hat MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Mon, 19 Aug 2019 20:52:06 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, 15 Aug 2019 21:02:58 +0800 Ben Luo wrote: > Currently, VFIO takes a lot of free-then-request-irq actions whenever > a VM (with device passthru via VFIO) sets irq affinity or mask/unmask > irq. Those actions only change the cookie data of irqaction or even > change nothing. The free-then-request-irq not only adds more latency, > but also increases the risk of losing interrupt, which may lead to a > VM hung forever in waiting for IO completion What guest environment is generating this? Typically I don't see that Windows or Linux guests bounce the interrupt configuration much. Thanks, Alex > > This patchset solved the issue by: > Patch 2 introduces update_irq_devid to only update dev_id of irqaction > Patch 3 make use of update_irq_devid and optimize irq operations in VFIO > > changes from v2: > - reformat to avoid quoted string split across lines and etc. > > changes from v1: > - add Patch 1 to enhance error recovery etc. in free irq per tglx's comments > - enhance error recovery code and debugging info in update_irq_devid > - use __must_check in external referencing of update_irq_devid > - use EXPORT_SYMBOL_GPL for update_irq_devid > - reformat code of patch 3 for better readability > > Ben Luo (3): > genirq: enhance error recovery code in free irq > genirq: introduce update_irq_devid() > vfio_pci: make use of update_irq_devid and optimize irq ops > > drivers/vfio/pci/vfio_pci_intrs.c | 101 +++++++++++++++++++++------------- > include/linux/interrupt.h | 3 ++ > kernel/irq/manage.c | 110 +++++++++++++++++++++++++++++++++----- > 3 files changed, 164 insertions(+), 50 deletions(-) >