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Tue, 16 Jun 2026 07:44:11 -0700 (PDT) Date: Tue, 16 Jun 2026 10:44:09 -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> 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: <4d8ddf50-e032-44a9-84d4-ddf2cd0c5bf6@kernel.org> On Tue, Jun 16, 2026 at 04:32:46PM +0200, David Hildenbrand (Arm) wrote: > On 6/16/26 15:57, Gregory Price wrote: > > > > Definitely an RFC here because I'm not sure if I was missing something > > that might help me solve the problem. > > Well, in QEMU we just run a timer internally that does the polling. > > Then, upper layers in the stack can ask QEMU for the latest stats. > > There, you just get the stats along with a "last-update" timestamp. > That makes sense, although don't you just push the blocking operation into yet another thread on the host? Assuming it's not cancel-able, there's a blocked thread there you have to reap. Vs the guest being unresponsive and not sending updates, you just reap the whole guest or take some other corrective action. I suppose to the orchestrator reaping QEMU and reaping the guest looks the same. The difference is just where the thread lives, hmmmm I'll make a note to inspect QEMU's solution to see if that's handled or if it would be subject to the same issue. Thanks! ~Gregory