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[82.30.61.225]) by smtp.gmail.com with ESMTPSA id n9sm36413638wrx.76.2022.02.23.01.56.10 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 23 Feb 2022 01:56:10 -0800 (PST) Date: Wed, 23 Feb 2022 09:56:08 +0000 From: "Dr. David Alan Gilbert" To: Peter Xu Subject: Re: [PATCH 18/20] migration: Postcopy preemption enablement Message-ID: References: <20220216062809.57179-1-peterx@redhat.com> <20220216062809.57179-19-peterx@redhat.com> MIME-Version: 1.0 In-Reply-To: User-Agent: Mutt/2.1.5 (2021-12-30) Authentication-Results: relay.mimecast.com; auth=pass smtp.auth=CUSA124A263 smtp.mailfrom=dgilbert@redhat.com X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Type: text/plain; charset=us-ascii Content-Disposition: inline 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: -28 X-Spam_score: -2.9 X-Spam_bar: -- X-Spam_report: (-2.9 / 5.0 requ) BAYES_00=-1.9, DKIMWL_WL_HIGH=-0.082, 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_H5=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: , Cc: Leonardo Bras Soares Passos , qemu-devel@nongnu.org, Juan Quintela Errors-To: qemu-devel-bounces+qemu-devel=archiver.kernel.org@nongnu.org Sender: "Qemu-devel" * Peter Xu (peterx@redhat.com) wrote: > On Tue, Feb 22, 2022 at 10:52:23AM +0000, Dr. David Alan Gilbert wrote: > > This does get a bit complicated, which worries me a bit; the code here > > is already quite complicated. > > Right, it's the way I chose in this patchset on solving this problem. Not > sure whether there's any better and easier way. > > For example, we could have used a new thread to send requested pages, and > synchronize it with the main thread. But that'll need other kind of > complexity, and I can't quickly tell whether that'll be better. > > For this single patch, more than half of the complexity comes from the > ability to interrupt sending one huge page half-way. It's a bit of a pity > that, that part will be noop ultimately when with doublemap. How does that huge-page interruption interact with recovery? i.e. do we know the start of that hugepage arrived? > > However I kept those only because we don't know when doublemap will be > ready, not to say, landing. Meanwhile we can't assume all kernels will > have doublemap even in the future. Yeh, if doublemap was already here you could make it a condition of allowing you to set the option. Dave > > (If you repost, there are a few 'channel' variables that could probably > > be 'unsigned' rather than int) > > That I can do for sure. > > > > > Reviewed-by: Dr. David Alan Gilbert > > Thanks, > > -- > Peter Xu > -- Dr. David Alan Gilbert / dgilbert@redhat.com / Manchester, UK