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 Received: from lists.gnu.org (lists.gnu.org [209.51.188.17]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 08F20C433EF for ; Thu, 13 Jan 2022 13:14:56 +0000 (UTC) Received: from localhost ([::1]:34992 helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1n7zwM-0006l0-9C for qemu-devel@archiver.kernel.org; Thu, 13 Jan 2022 08:14:54 -0500 Received: from eggs.gnu.org ([209.51.188.92]:50786) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n7zsL-00056u-2I for qemu-devel@nongnu.org; Thu, 13 Jan 2022 08:10:46 -0500 Received: from us-smtp-delivery-124.mimecast.com ([170.10.129.124]:52930) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1n7zsB-00016q-Ni for qemu-devel@nongnu.org; Thu, 13 Jan 2022 08:10:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1642079431; h=from:from:reply-to:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=FzPPB3BQ/nkgp793b/k7wZKQJ7hPiD+ODAZBYFdWHnk=; b=SasXq5Iq1TYLSQRTSHtx5l6nQgfMnzbsGGiUBI6xxaI+O9btlMWmWOdmxats3tkpabsmDV 5ltfkEzqfOn7RkLhSbhU6NZToEabrJ7Cd6Lbq5HIqmnVgFCpoev6DEgjE0RZiRiemJzzZc 4O3l8ZOO2+RqWyW3X8Zf/t9WxcEMIHk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-515-ynOC1U-BOkSSctlluV6HwA-1; Thu, 13 Jan 2022 08:10:30 -0500 X-MC-Unique: ynOC1U-BOkSSctlluV6HwA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.phx2.redhat.com [10.5.11.15]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id D587D1023F4F for ; Thu, 13 Jan 2022 13:10:28 +0000 (UTC) Received: from redhat.com (unknown [10.33.37.41]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 2A3CD708F4; Thu, 13 Jan 2022 13:09:59 +0000 (UTC) Date: Thu, 13 Jan 2022 13:09:57 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: Leonardo Bras Subject: Re: [PATCH v7 3/5] migration: Add zero-copy parameter for QMP/HMP for Linux Message-ID: References: <20220106221341.8779-1-leobras@redhat.com> <20220106221341.8779-4-leobras@redhat.com> MIME-Version: 1.0 In-Reply-To: <20220106221341.8779-4-leobras@redhat.com> User-Agent: Mutt/2.1.3 (2021-09-10) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.15 Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=berrange@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit Received-SPF: pass client-ip=170.10.129.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -33 X-Spam_score: -3.4 X-Spam_bar: --- X-Spam_report: (-3.4 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.594, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, RCVD_IN_MSPIKE_H3=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=ham autolearn_force=no X-Spam_action: no action X-BeenThere: qemu-devel@nongnu.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= Cc: Juan Quintela , qemu-devel@nongnu.org, Peter Xu , Markus Armbruster , Eric Blake , "Dr. David Alan Gilbert" Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" On Thu, Jan 06, 2022 at 07:13:40PM -0300, Leonardo Bras wrote: > Add property that allows zero-copy migration of memory pages, > and also includes a helper function migrate_use_zero_copy() to check > if it's enabled. > > No code is introduced to actually do the migration, but it allow > future implementations to enable/disable this feature. > > On non-Linux builds this parameter is compiled-out. > > Signed-off-by: Leonardo Bras > --- > qapi/migration.json | 24 ++++++++++++++++++++++++ > migration/migration.h | 5 +++++ > migration/migration.c | 32 ++++++++++++++++++++++++++++++++ > migration/socket.c | 5 +++++ > monitor/hmp-cmds.c | 6 ++++++ > 5 files changed, 72 insertions(+) Reviewed-by: Daniel P. Berrangé > > diff --git a/qapi/migration.json b/qapi/migration.json > index bbfd48cf0b..2e62ea6ebd 100644 > --- a/qapi/migration.json > +++ b/qapi/migration.json > @@ -730,6 +730,13 @@ > # will consume more CPU. > # Defaults to 1. (Since 5.0) > # > +# @zero-copy: Controls behavior on sending memory pages on migration. > +# When true, enables a zero-copy mechanism for sending memory > +# pages, if host supports it. > +# Requires that QEMU be permitted to use locked memory for guest > +# RAM pages. > +# Defaults to false. (Since 7.0) > +# > # @block-bitmap-mapping: Maps block nodes and bitmaps on them to > # aliases for the purpose of dirty bitmap migration. Such > # aliases may for example be the corresponding names on the > @@ -769,6 +776,7 @@ > 'xbzrle-cache-size', 'max-postcopy-bandwidth', > 'max-cpu-throttle', 'multifd-compression', > 'multifd-zlib-level' ,'multifd-zstd-level', > + { 'name': 'zero-copy', 'if' : 'CONFIG_LINUX'}, > 'block-bitmap-mapping' ] } > > ## > @@ -895,6 +903,13 @@ > # will consume more CPU. > # Defaults to 1. (Since 5.0) > # > +# @zero-copy: Controls behavior on sending memory pages on migration. > +# When true, enables a zero-copy mechanism for sending memory > +# pages, if host supports it. > +# Requires that QEMU be permitted to use locked memory for guest > +# RAM pages. > +# Defaults to false. (Since 7.0) > +# > # @block-bitmap-mapping: Maps block nodes and bitmaps on them to > # aliases for the purpose of dirty bitmap migration. Such > # aliases may for example be the corresponding names on the > @@ -949,6 +964,7 @@ > '*multifd-compression': 'MultiFDCompression', > '*multifd-zlib-level': 'uint8', > '*multifd-zstd-level': 'uint8', > + '*zero-copy': { 'type': 'bool', 'if': 'CONFIG_LINUX' }, > '*block-bitmap-mapping': [ 'BitmapMigrationNodeAlias' ] } } The current zerocopy impl is for the send path. Do you expect we might get zerocopy in the receive path later ? If so then either call this 'send-zero-copy', or change it from a bool to an enum taking '["send", "recv", "both"]'. I'd probably take the former and just rename it. Regards, Daniel -- |: https://berrange.com -o- https://www.flickr.com/photos/dberrange :| |: https://libvirt.org -o- https://fstop138.berrange.com :| |: https://entangle-photo.org -o- https://www.instagram.com/dberrange :|