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=-1.0 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS 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 E524CC43387 for ; Mon, 7 Jan 2019 14:47:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B962D2183E for ; Mon, 7 Jan 2019 14:47:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729113AbfAGOrX (ORCPT ); Mon, 7 Jan 2019 09:47:23 -0500 Received: from mx1.redhat.com ([209.132.183.28]:47196 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729046AbfAGOrX (ORCPT ); Mon, 7 Jan 2019 09:47:23 -0500 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 1D52D81F13; Mon, 7 Jan 2019 14:47:23 +0000 (UTC) Received: from redhat.com (ovpn-122-143.rdu2.redhat.com [10.10.122.143]) by smtp.corp.redhat.com (Postfix) with ESMTP id 42F3E61D38; Mon, 7 Jan 2019 14:47:22 +0000 (UTC) Date: Mon, 7 Jan 2019 09:47:21 -0500 From: "Michael S. Tsirkin" To: Jason Wang Cc: kvm@vger.kernel.org, virtualization@lists.linux-foundation.org, netdev@vger.kernel.org, linux-kernel@vger.kernel.org, davem@davemloft.net Subject: Re: [RFC PATCH V3 0/5] Hi: Message-ID: <20190107094516-mutt-send-email-mst@kernel.org> References: <20181229124656.3900-1-jasowang@redhat.com> <20190104163516-mutt-send-email-mst@kernel.org> <68727e1b-1d51-0596-29c3-931475dd5dab@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <68727e1b-1d51-0596-29c3-931475dd5dab@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.27]); Mon, 07 Jan 2019 14:47:23 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jan 07, 2019 at 02:58:08PM +0800, Jason Wang wrote: > > On 2019/1/5 上午5:41, Michael S. Tsirkin wrote: > > On Sat, Dec 29, 2018 at 08:46:51PM +0800, Jason Wang wrote: > > > This series tries to access virtqueue metadata through kernel virtual > > > address instead of copy_user() friends since they had too much > > > overheads like checks, spec barriers or even hardware feature > > > toggling. > > > > I think it's a reasonable approach. > > However I need to look at whether and which mmu notifiers are invoked before > > writeback. Do you know? > > > I don't know but just looking at the MMU notifier ops definition, there's no > such callback if my understanding is correct. > > Thanks In that case how are you making sure used ring updates are written back? If they aren't guest will crash ... > > > > > > Test shows about 24% improvement on TX PPS. It should benefit other > > > cases as well. > > > > > > Changes from V2: > > > - fix buggy range overlapping check > > > - tear down MMU notifier during vhost ioctl to make sure invalidation > > > request can read metadata userspace address and vq size without > > > holding vq mutex. > > > Changes from V1: > > > - instead of pinning pages, use MMU notifier to invalidate vmaps and > > > remap duing metadata prefetch > > > - fix build warning on MIPS > > > > > > Jason Wang (5): > > > vhost: generalize adding used elem > > > vhost: fine grain userspace memory accessors > > > vhost: rename vq_iotlb_prefetch() to vq_meta_prefetch() > > > vhost: introduce helpers to get the size of metadata area > > > vhost: access vq metadata through kernel virtual address > > > > > > drivers/vhost/net.c | 4 +- > > > drivers/vhost/vhost.c | 416 +++++++++++++++++++++++++++++++++++++----- > > > drivers/vhost/vhost.h | 15 +- > > > 3 files changed, 384 insertions(+), 51 deletions(-) > > > > > > -- > > > 2.17.1