From patchwork Thu Aug 30 16:17:19 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Peng Hao X-Patchwork-Id: 10581309 Return-Path: Received: from mail.wl.linuxfoundation.org (pdx-wl-mail.web.codeaurora.org [172.30.200.125]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id B5F3014E1 for ; Thu, 30 Aug 2018 08:03:33 +0000 (UTC) Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id AAEB72B7B4 for ; Thu, 30 Aug 2018 08:03:33 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 9DC412B7BF; Thu, 30 Aug 2018 08:03:33 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on pdx-wl-mail.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-4.9 required=2.0 tests=BAYES_00,DATE_IN_FUTURE_03_06, MAILING_LIST_MULTI,RCVD_IN_DNSWL_HI autolearn=ham version=3.3.1 Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 425452B7B4 for ; Thu, 30 Aug 2018 08:03:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727730AbeH3MEG (ORCPT ); Thu, 30 Aug 2018 08:04:06 -0400 Received: from out1.zte.com.cn ([202.103.147.172]:59202 "EHLO mxct.zte.com.cn" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727626AbeH3MEG (ORCPT ); Thu, 30 Aug 2018 08:04:06 -0400 Received: from mse01.zte.com.cn (unknown [10.30.3.20]) by Forcepoint Email with ESMTPS id 1D3C3CA7767842600E87; Thu, 30 Aug 2018 16:03:10 +0800 (CST) Received: from notes_smtp.zte.com.cn ([10.30.1.239]) by mse01.zte.com.cn with ESMTP id w7U834lQ016014; Thu, 30 Aug 2018 16:03:04 +0800 (GMT-8) (envelope-from peng.hao2@zte.com.cn) Received: from localhost.localdomain.localdomain ([10.74.120.59]) by szsmtp06.zte.com.cn (Lotus Domino Release 8.5.3FP6) with ESMTP id 2018083016031230-6559975 ; Thu, 30 Aug 2018 16:03:12 +0800 From: Peng Hao To: pbonzini@redhat.com, rkrcmar@redhat.com Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, zhong.weidong@zte.com.cn, wanpeng.li@hotmail.com, Peng Hao Subject: [PATCH V4 0/2] introduce coalesced pio support Date: Fri, 31 Aug 2018 00:17:19 +0800 Message-Id: <1535645841-111837-1-git-send-email-peng.hao2@zte.com.cn> X-Mailer: git-send-email 1.8.3.1 X-MIMETrack: Itemize by SMTP Server on SZSMTP06/server/zte_ltd(Release 8.5.3FP6|November 21, 2013) at 2018-08-30 16:03:12, Serialize by Router on notes_smtp/zte_ltd(Release 9.0.1FP7|August 17, 2016) at 2018-08-30 16:02:53, Serialize complete at 2018-08-30 16:02:53 X-MAIL: mse01.zte.com.cn w7U834lQ016014 Sender: kvm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org X-Virus-Scanned: ClamAV using ClamSMTP Coalesced pio is base on coalesced mmio and can be used for some port like rtc port, pci-host config port, virtio-pci config port and so on. Specially in case of rtc as coalesced pio, some versions of windows guest access rtc frequently because of rtc as system tick. guest access rtc like this: write register index to 0x70, then write or read data from 0x71. writing 0x70 port is just as index and do nothing else. So we can use coalesced pio to handle this scene to reduce VM-EXIT time. When it starts and closes the virtual machine, it will access pci-host config port or virtio-pci config port frequently. So setting these port as coalesced pio can reduce startup and shutdown time. In qemu I just realize piixfx's pci-host, it is convenient for other pci-host type implementations. without my patch, get the vm-exit time of accessing rtc 0x70 and piix 0xcf8 using perf tools: (guest OS : windows 7 64bit) IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 86 30.99% 74.59% 9us 29us 10.75us (+- 3.41%) 0xcf8:POUT 1119 2.60% 2.12% 2.79us 56.83us 3.41us (+- 2.23%) with my patch IO Port Access Samples Samples% Time% Min Time Max Time Avg time 0x70:POUT 106 32.02% 29.47% 0us 10us 1.57us (+- 7.38%) 0xcf8:POUT 1065 1.67% 0.28% 0.41us 65.44us 0.66us (+- 10.55%) Peng Hao (2): kvm/x86 : add coalesced pio support kvm/x86 : add document for coalesced pio Documentation/virtual/kvm/00-INDEX | 2 ++ Documentation/virtual/kvm/coalesced-pio.txt | 15 ++++++++++++++ include/uapi/linux/kvm.h | 11 +++++++++-- virt/kvm/coalesced_mmio.c | 12 +++++++++--- virt/kvm/kvm_main.c | 2 ++ 5 files changed, 37 insertions(+), 5 deletions(-) create mode 100644 Documentation/virtual/kvm/coalesced-pio.txt