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 32FAFC43387 for ; Fri, 4 Jan 2019 21:41:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id EEDD821872 for ; Fri, 4 Jan 2019 21:41:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726388AbfADVl0 (ORCPT ); Fri, 4 Jan 2019 16:41:26 -0500 Received: from mx1.redhat.com ([209.132.183.28]:48016 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726097AbfADVlZ (ORCPT ); Fri, 4 Jan 2019 16:41:25 -0500 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id A7E86637FF; Fri, 4 Jan 2019 21:41:25 +0000 (UTC) Received: from redhat.com (ovpn-124-210.rdu2.redhat.com [10.10.124.210]) by smtp.corp.redhat.com (Postfix) with SMTP id C66005D9C5; Fri, 4 Jan 2019 21:41:24 +0000 (UTC) Date: Fri, 4 Jan 2019 16:41:24 -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: <20190104163516-mutt-send-email-mst@kernel.org> References: <20181229124656.3900-1-jasowang@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181229124656.3900-1-jasowang@redhat.com> X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.28]); Fri, 04 Jan 2019 21:41:25 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? > 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