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 668A5C54E58 for ; Wed, 20 Mar 2024 15:21:15 +0000 (UTC) Received: from localhost ([::1] helo=lists1p.gnu.org) by lists.gnu.org with esmtp (Exim 4.90_1) (envelope-from ) id 1rmxkT-0005b3-I5; Wed, 20 Mar 2024 11:21:01 -0400 Received: from eggs.gnu.org ([2001:470:142:3::10]) by lists.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rmxkS-0005al-77 for qemu-devel@nongnu.org; Wed, 20 Mar 2024 11:21:00 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by eggs.gnu.org with esmtps (TLS1.2:ECDHE_RSA_AES_256_GCM_SHA384:256) (Exim 4.90_1) (envelope-from ) id 1rmxkQ-0001T0-9I for qemu-devel@nongnu.org; Wed, 20 Mar 2024 11:20:59 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1710948057; 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=dF9CCaaEdhClCGSB3+SIvhPc8jonNw0nYKj1rBybd68=; b=BgXRF0FudtOTp1TSQroNjQ2gOhJJ/lJ5JZRp4QRZuUeAxWEFoMaX1ll/KnkZHHC/2R+dy2 Uuz5R5k/m/fcKQJlmVyEAA0+lCzyH3VGAoFXFrsvOG+JgvkAvrKT5tvwbmcgeYIHl4vFEF iGmafHFSV0/WtkbOPk4IWtji/8P+SUM= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-474-KuGOTxGnOLKNBaI1Bw7kqA-1; Wed, 20 Mar 2024 11:20:53 -0400 X-MC-Unique: KuGOTxGnOLKNBaI1Bw7kqA-1 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 64EA8101A523; Wed, 20 Mar 2024 15:20:53 +0000 (UTC) Received: from redhat.com (unknown [10.42.28.205]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 4032B10E47; Wed, 20 Mar 2024 15:20:51 +0000 (UTC) Date: Wed, 20 Mar 2024 15:20:45 +0000 From: Daniel =?utf-8?B?UC4gQmVycmFuZ8Op?= To: "Liu, Yuan1" Cc: "peterx@redhat.com" , "farosas@suse.de" , "qemu-devel@nongnu.org" , "hao.xiang@bytedance.com" , "bryan.zhang@bytedance.com" , "Zou, Nanhai" Subject: Re: [PATCH v5 5/7] migration/multifd: implement initialization of qpl compression Message-ID: References: <20240319164527.1873891-1-yuan1.liu@intel.com> <20240319164527.1873891-6-yuan1.liu@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: User-Agent: Mutt/2.2.12 (2023-09-09) X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.5 Received-SPF: pass client-ip=170.10.133.124; envelope-from=berrange@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -24 X-Spam_score: -2.5 X-Spam_bar: -- X-Spam_report: (-2.5 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.417, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_NONE=-0.0001, RCVD_IN_MSPIKE_H4=0.001, RCVD_IN_MSPIKE_WL=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001, T_SCC_BODY_TEXT_LINE=-0.01 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?= Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org On Wed, Mar 20, 2024 at 03:02:59PM +0000, Liu, Yuan1 wrote: > > -----Original Message----- > > From: Daniel P. Berrangé > > Sent: Wednesday, March 20, 2024 6:42 PM > > To: Liu, Yuan1 > > Cc: peterx@redhat.com; farosas@suse.de; qemu-devel@nongnu.org; > > hao.xiang@bytedance.com; bryan.zhang@bytedance.com; Zou, Nanhai > > > > Subject: Re: [PATCH v5 5/7] migration/multifd: implement initialization of > > qpl compression > > > > On Wed, Mar 20, 2024 at 12:45:25AM +0800, Yuan Liu wrote: > > > the qpl initialization includes memory allocation for compressed > > > data and the qpl job initialization. > > > > > > the qpl initialization will check whether the In-Memory Analytics > > > Accelerator(IAA) hardware is available, if the platform does not > > > have IAA hardware or the IAA hardware is not available, the QPL > > > compression initialization will fail. > > > > > > Signed-off-by: Yuan Liu > > > Reviewed-by: Nanhai Zou > > > --- > > > migration/multifd-qpl.c | 243 +++++++++++++++++++++++++++++++++++++++- > > > 1 file changed, 242 insertions(+), 1 deletion(-) > > > > > > diff --git a/migration/multifd-qpl.c b/migration/multifd-qpl.c > > > index 056a68a060..6de65e9da7 100644 > > > --- a/migration/multifd-qpl.c > > > +++ b/migration/multifd-qpl.c > > > @@ -9,12 +9,253 @@ > > > * This work is licensed under the terms of the GNU GPL, version 2 or > > later. > > > * See the COPYING file in the top-level directory. > > > */ > > > + > > > #include "qemu/osdep.h" > > > #include "qemu/module.h" > > > +#include "qapi/error.h" > > > +#include "migration.h" > > > +#include "multifd.h" > > > +#include "qpl/qpl.h" > > > + > > > +typedef struct { > > > + qpl_job **job_array; > > > + /* the number of allocated jobs */ > > > + uint32_t job_num; > > > + /* the size of data processed by a qpl job */ > > > + uint32_t data_size; > > > + /* compressed data buffer */ > > > + uint8_t *zbuf; > > > + /* the length of compressed data */ > > > + uint32_t *zbuf_hdr; > > > +} QplData; > > > + > > > +static void free_zbuf(QplData *qpl) > > > +{ > > > + if (qpl->zbuf != NULL) { > > > + munmap(qpl->zbuf, qpl->job_num * qpl->data_size); > > > + qpl->zbuf = NULL; > > > + } > > > + if (qpl->zbuf_hdr != NULL) { > > > + g_free(qpl->zbuf_hdr); > > > + qpl->zbuf_hdr = NULL; > > > + } > > > +} > > > + > > > +static int alloc_zbuf(QplData *qpl, uint8_t chan_id, Error **errp) > > > +{ > > > + int flags = MAP_PRIVATE | MAP_POPULATE | MAP_ANONYMOUS; > > > + uint32_t size = qpl->job_num * qpl->data_size; > > > + uint8_t *buf; > > > + > > > + buf = (uint8_t *) mmap(NULL, size, PROT_READ | PROT_WRITE, flags, - > > 1, 0); > > > + if (buf == MAP_FAILED) { > > > + error_setg(errp, "multifd: %u: alloc_zbuf failed, job num %u, > > size %u", > > > + chan_id, qpl->job_num, qpl->data_size); > > > + return -1; > > > + } > > > > What's the reason for using mmap here, rather than a normal > > malloc ? > > I want to populate the memory accessed by the IAA device in the initialization > phase, and then avoid initiating I/O page faults through the IAA device during > migration, a large number of I/O page faults are not good for performance. Does this mmap actually make a measurable difference ? If I've followed the code paths correctly, I think this alloc_zbuf method only gets called during initial setup of each migration thread. So this use of MAP_POPULATE seems to only make a difference between faulting in before starting sending data, and faulting in on first bit of data that's sent. I'm surprised if that's noticable as a difference. > This problem also occurs at the destination, therefore, I recommend that > customers need to add -mem-prealloc for destination boot parameters. I can understand mem-prelloc making a difference as that guarantees all of guest RAM is faulted in. With 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 :|