From patchwork Thu Nov 6 11:08:47 2014 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Li, Liang Z" X-Patchwork-Id: 407403 Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Received: from lists.gnu.org (lists.gnu.org [IPv6:2001:4830:134:3::11]) (using TLSv1 with cipher AES256-SHA (256/256 bits)) (No client certificate requested) by ozlabs.org (Postfix) with ESMTPS id C9AEC140098 for ; Thu, 6 Nov 2014 22:16:26 +1100 (AEDT) Received: from localhost ([::1]:52043 helo=lists.gnu.org) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XmL3A-00071z-Tu for incoming@patchwork.ozlabs.org; Thu, 06 Nov 2014 06:16:24 -0500 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36189) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XmL2c-0006GC-So for qemu-devel@nongnu.org; Thu, 06 Nov 2014 06:15:55 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XmL2X-0001WY-PH for qemu-devel@nongnu.org; Thu, 06 Nov 2014 06:15:50 -0500 Received: from mga14.intel.com ([192.55.52.115]:16227) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XmL2X-0001WB-5C for qemu-devel@nongnu.org; Thu, 06 Nov 2014 06:15:45 -0500 Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga103.fm.intel.com with ESMTP; 06 Nov 2014 03:09:25 -0800 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.07,325,1413270000"; d="scan'208";a="618134430" Received: from lil.sh.intel.com (HELO localhost) ([10.239.36.68]) by fmsmga001.fm.intel.com with ESMTP; 06 Nov 2014 03:15:39 -0800 From: Li Liang To: qemu-devel@nongnu.org Date: Thu, 6 Nov 2014 19:08:47 +0800 Message-Id: <1415272128-8273-2-git-send-email-liang.z.li@intel.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1415272128-8273-1-git-send-email-liang.z.li@intel.com> References: <1415272128-8273-1-git-send-email-liang.z.li@intel.com> X-detected-operating-system: by eggs.gnu.org: Genre and OS details not recognized. X-Received-From: 192.55.52.115 Cc: yang.z.zhang@intel.com, Li Liang , armbru@redhat.com, lcapitulino@redhat.com Subject: [Qemu-devel] [v2 1/2] docs: Add a doc about multiple compression threads X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.14 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Sender: qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org Give some details about the multiple compression threads and how to use it in live migration. Signed-off-by: Li Liang --- docs/multiple-compression-threads.txt | 128 ++++++++++++++++++++++++++++++++++ 1 file changed, 128 insertions(+) create mode 100644 docs/multiple-compression-threads.txt diff --git a/docs/multiple-compression-threads.txt b/docs/multiple-compression-threads.txt new file mode 100644 index 0000000..a5e53de --- /dev/null +++ b/docs/multiple-compression-threads.txt @@ -0,0 +1,128 @@ +Use multiple (de)compression threads in live migration +================================================================= +Copyright (C) 2014 Li Liang + + +Contents: +========= +* Introduction +* When to use +* Performance +* Usage +* TODO + +Introduction +============ +Instead of sending the guest memory directly, this solution will +compress the ram page before sending, after receiving, the data will +be decompressed. Using compression in live migration can help +to reduce the data transferred about 60%, this is very useful when the +bandwidth is limited, and the migration time can also be reduced about +70% in a typical case. + +The process of compression will consume additional CPU cycles, and the +extra CPU cycles will increase the migration time. On the other hand, +the amount of data transferred will reduced, this factor can reduce +the migration time. If the process of the compression is quick +enough, then the total migration time can be reduced, and multiple +compression threads can be used to accelerate the compression process. + +The decompression speed of zlib is at least 4 times as quickly as +compression, if the source and destination CPU have equal speed, +keeping the compression thread count 4 times the decompression +thread count can avoid CPU waste. + +Compression level can be used to control the compression speed and the +compression ratio. High compression ratio will take more time, level 0 +stands for no compression, level 1 stands for the best compression +speed, and level 9 stands for the best compression ratio. Users can +select a level number between 0 and 9. + + +When to use the multiple compression threads in live migration +============================================================== +Compression of data will consume lot of extra CPU cycles, in a system +with high overhead of CPU, avoid using this feature. When the network +bandwidth is very limited and the CPU resource is adequate, use the +multiple compression threads will be very helpful. If both the CPU and +the network bandwidth are adequate, use multiple compression threads +can still help to reduce the migration time. + +Performance +=========== +Test environment: + +CPU: Intel(R) Xeon(R) CPU E5-2680 0 @ 2.70GHz +Socket Count: 2 +Ram: 128G +NIC: Intel I350 (10/100/1000Mbps) +Host OS: CentOS 7 64-bit +Guest OS: Ubuntu 12.10 64-bit +Parameter: qemu-system-x86_64 -enable-kvm -m 1024 + /share/ia32e_ubuntu12.10.img -monitor stdio + +There is no additional application is running on the guest when doing +the test. + + +Speed limit: 32MB/s +--------------------------------------------------------------- + | original | compress thread: 8 + | way | decompress thread: 2 + | | compression level: 1 +--------------------------------------------------------------- +total time(msec): | 26561 | 7920 +--------------------------------------------------------------- +transferred ram(kB):| 877054 | 260641 +--------------------------------------------------------------- +throughput(mbps): | 270.53 | 269.68 +--------------------------------------------------------------- +total ram(kB): | 1057604 | 1057604 +--------------------------------------------------------------- + + +Speed limit: No +--------------------------------------------------------------- + | original | compress thread: 15 + | way | decompress thread: 4 + | | compression level: 1 +--------------------------------------------------------------- +total time(msec): | 7611 | 2888 +--------------------------------------------------------------- +transferred ram(kB):| 876761 | 262301 +--------------------------------------------------------------- +throughput(mbps): | 943.78 | 744.27 +--------------------------------------------------------------- +total ram(kB): | 1057604 | 1057604 +--------------------------------------------------------------- + +Usage +====== +1. Verify the destination QEMU version is able to support the multiple +compression threads migration: + {qemu} info_migrate_capablilites + {qemu} ... compress: off ... + +2. Activate compression on the souce: + {qemu} migrate_set_capability compress on + +3. Set the compression thread count on source: + {qemu} migrate_set_compress_threads 10 + +4. Set the compression level on the source: + {qemu} migrate_set_compress_level 1 + +5. Set the decompression thread count on destination: + {qemu} migrate_set_decompress_threads 5 + +6. Start outgoing migration: + {qemu} migrate -d tcp:destination.host:4444 + {qemu} info migrate + Capabilities: ... compress: on + ... + +TODO +==== +Some faster compression/decompression method such as lz4 and quicklz +can help to reduce the CPU consumption when doing (de)compression. +Less (de)compression threads are needed when doing the migration.