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[82.30.61.225]) by smtp.gmail.com with ESMTPSA id x13-20020adff0cd000000b002205cbc1c74sm5225480wro.101.2022.09.22.09.29.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Sep 2022 09:29:02 -0700 (PDT) Date: Thu, 22 Sep 2022 17:29:00 +0100 From: "Dr. David Alan Gilbert" To: Peter Xu Cc: qemu-devel@nongnu.org, "Daniel P . Berrange" , Leonardo Bras Soares Passos , Juan Quintela Subject: Re: [PATCH 4/5] migration: Disallow postcopy preempt to be used with compress Message-ID: References: <20220920223800.47467-1-peterx@redhat.com> <20220920223800.47467-5-peterx@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220920223800.47467-5-peterx@redhat.com> User-Agent: Mutt/2.2.7 (2022-08-07) Received-SPF: pass client-ip=170.10.133.124; envelope-from=dgilbert@redhat.com; helo=us-smtp-delivery-124.mimecast.com X-Spam_score_int: -27 X-Spam_score: -2.8 X-Spam_bar: -- X-Spam_report: (-2.8 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.001, DKIM_SIGNED=0.1, DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, RCVD_IN_DNSWL_LOW=-0.7, 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: , Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Peter Xu (peterx@redhat.com) wrote: > The preempt mode requires the capability to assign channel for each of the > page, while the compression logic will currently assign pages to different > compress thread/local-channel so potentially they're incompatible. > > Signed-off-by: Peter Xu Reviewed-by: Dr. David Alan Gilbert > --- > migration/migration.c | 11 +++++++++++ > 1 file changed, 11 insertions(+) > > diff --git a/migration/migration.c b/migration/migration.c > index fb4066dfb4..07c74a79a2 100644 > --- a/migration/migration.c > +++ b/migration/migration.c > @@ -1341,6 +1341,17 @@ static bool migrate_caps_check(bool *cap_list, > error_setg(errp, "Postcopy preempt requires postcopy-ram"); > return false; > } > + > + /* > + * Preempt mode requires urgent pages to be sent in separate > + * channel, OTOH compression logic will disorder all pages into > + * different compression channels, which is not compatible with the > + * preempt assumptions on channel assignments. > + */ > + if (cap_list[MIGRATION_CAPABILITY_COMPRESS]) { > + error_setg(errp, "Postcopy preempt not compatible with compress"); > + return false; > + } > } > > return true; > -- > 2.32.0 > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK