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Tue, 16 Jun 2026 08:58:24 -0700 (PDT) Date: Tue, 16 Jun 2026 11:58:22 -0400 From: Gregory Price To: "David Hildenbrand (Arm)" Cc: virtualization@lists.linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com, mst@redhat.com, jasowang@redhat.com, xuanzhuo@linux.alibaba.com, eperezma@redhat.com, hannes@cmpxchg.org, surenb@google.com, peterz@infradead.org, mingo@redhat.com, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, bsegall@google.com, mgorman@suse.de, vschneid@redhat.com, kprateek.nayak@amd.com Subject: Re: [RFC PATCH 2/2] virtio-balloon: add stats push mode Message-ID: References: <20260513165006.2790857-1-gourry@gourry.net> <20260513165006.2790857-3-gourry@gourry.net> <4d8ddf50-e032-44a9-84d4-ddf2cd0c5bf6@kernel.org> <3e7d2d74-ceb2-4064-928f-921401fea75e@kernel.org> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <3e7d2d74-ceb2-4064-928f-921401fea75e@kernel.org> On Tue, Jun 16, 2026 at 05:52:29PM +0200, David Hildenbrand (Arm) wrote: > On 6/16/26 16:44, Gregory Price wrote: > > That makes sense, although don't you just push the blocking operation > > into yet another thread on the host? > > I think timers are run from the QEMU main thread, so no separate thread just for > the timer. > > And IIRC, there will be no blocking. At least if I understand your concern > correctly. > > balloon_stats_poll_cb() will do a virtqueue_push()+virtio_notify(), which will > notify the device. The main thread will continue afterwards doing what a main > thread usually does. > > A VCPU will process the request in the VM and send it back + notify the device. > Entirely possible I just bungled the interaction then and/or CH's interfaces introduce a blocking op that shouldn't. Thanks for the feedback, we can probably drop this patch. Unless there's any particular pushback for 1/2, should i leave as-is or resubmit separately w/o RFC? ~Gregory