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Tsirkin" , Peter Maydell , qemu-block@nongnu.org, Stefan Hajnoczi , Kevin Wolf , =?UTF-8?q?Daniel=20P=2E=20Berrang=C3=A9?= Subject: [PATCH 24/31] hw/ppc/pnv_occ: skip automatic zero-init of large struct Date: Tue, 10 Jun 2025 13:37:02 +0100 Message-ID: <20250610123709.835102-25-berrange@redhat.com> In-Reply-To: <20250610123709.835102-1-berrange@redhat.com> References: <20250610123709.835102-1-berrange@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.4.1 on 10.30.177.4 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: -20 X-Spam_score: -2.1 X-Spam_bar: -- X-Spam_report: (-2.1 / 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_NONE=-0.0001, RCVD_IN_MSPIKE_H5=0.001, RCVD_IN_MSPIKE_WL=0.001, RCVD_IN_VALIDITY_RPBL_BLOCKED=0.001, RCVD_IN_VALIDITY_SAFE_BLOCKED=0.001, SPF_HELO_NONE=0.001, SPF_PASS=-0.001 autolearn=unavailable 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-bounces+qemu-devel=archiver.kernel.org@nongnu.org The 'occ_model_tick' method has a 12k struct used for copying data between guest and host. Skip the automatic zero-init of this struct to eliminate the performance overhead in the I/O hot path. The 'dynamic_data' buffer will be fully initialized when reading data from the guest. Signed-off-by: Daniel P. Berrangé --- hw/ppc/pnv_occ.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/hw/ppc/pnv_occ.c b/hw/ppc/pnv_occ.c index fa6f31cb8d..24b789c191 100644 --- a/hw/ppc/pnv_occ.c +++ b/hw/ppc/pnv_occ.c @@ -789,7 +789,7 @@ static bool occ_opal_process_command(PnvOCC *occ, static bool occ_model_tick(PnvOCC *occ) { - struct occ_dynamic_data dynamic_data; + QEMU_UNINITIALIZED struct occ_dynamic_data dynamic_data; if (!occ_read_dynamic_data(occ, &dynamic_data, NULL)) { /* Can't move OCC state field to safe because we can't map it! */ -- 2.49.0