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GET /api/patches/2217867/?format=api
{ "id": 2217867, "url": "http://patchwork.ozlabs.org/api/patches/2217867/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260330192701.75780-1-maxpain@linux.com/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/projects/14/?format=api", "name": "QEMU Development", "link_name": "qemu-devel", "list_id": "qemu-devel.nongnu.org", "list_email": "qemu-devel@nongnu.org", "web_url": "", "scm_url": "", "webscm_url": "", "list_archive_url": "", "list_archive_url_format": "", "commit_url_format": "" }, "msgid": "<20260330192701.75780-1-maxpain@linux.com>", "list_archive_url": null, "date": "2026-03-30T19:27:01", "name": "vhost-user-blk-server: fix opt_io_size=1 causing severe Windows I/O degradation", "commit_ref": null, "pull_url": null, "state": "new", "archived": false, "hash": "cb9e51f197782dc3abcd12667680f43ac5336ce8", "submitter": { "id": 93011, "url": "http://patchwork.ozlabs.org/api/people/93011/?format=api", "name": "Max Makarov", "email": "maxpain177@gmail.com" }, "delegate": null, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260330192701.75780-1-maxpain@linux.com/mbox/", "series": [ { "id": 498084, "url": "http://patchwork.ozlabs.org/api/series/498084/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=498084", "date": "2026-03-30T19:27:01", "name": "vhost-user-blk-server: fix opt_io_size=1 causing severe Windows I/O degradation", "version": 1, "mbox": "http://patchwork.ozlabs.org/series/498084/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2217867/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2217867/checks/", "tags": {}, "related": [], "headers": { "Return-Path": "<qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org>", "X-Original-To": "incoming@patchwork.ozlabs.org", "Delivered-To": "patchwork-incoming@legolas.ozlabs.org", "Authentication-Results": [ "legolas.ozlabs.org;\n\tdkim=pass (2048-bit key;\n unprotected) header.d=gmail.com header.i=@gmail.com header.a=rsa-sha256\n header.s=20251104 header.b=FMg2kczL;\n\tdkim-atps=neutral", "legolas.ozlabs.org;\n spf=pass (sender SPF authorized) smtp.mailfrom=nongnu.org\n (client-ip=209.51.188.17; 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a=rsa-sha256; c=relaxed/relaxed;\n d=1e100.net; s=20251104; t=1774898823; x=1775503623;\n h=content-transfer-encoding:mime-version:message-id:date:subject:cc\n :to:from:x-gm-gg:x-gm-message-state:from:to:cc:subject:date\n :message-id:reply-to;\n bh=O84wtaC2zyHfbP85d7pv0VHeETj9qzSLnqvEcLsal64=;\n b=gFB6YEeF8ETo6quZ0cHSBdsQ73OVUKh3aY7E/QkWsXz7rE7/bjgTSY1h0Cl/3A4Pbx\n KAdOJ5z1qHYXu6CPDgJtcca4jMmswoiOG32BaWa4D9pWo0Rqwtnpx4Cz9ZE65TcQwB6z\n fq6wCxicp+ZyRKcUxbI2pcV8tbtUZWP+AysT/4wgKfYbMv3yxttEypspFsWpYPKCF6m/\n 44d+i+jEur2GeRVIUcoOKpK+hA6c+HEjvcDzw+Rir09FA7D1wiMwDcjKJZfVT6DkfiYT\n QKmlaFc6StfI0NaujfD/uUzWjIfCehgxT3Gmcdgwj2GsK85g4zj0XJMJFYlfnxR0NpIY\n in9A==", "X-Gm-Message-State": "AOJu0YyczCzeGT3tAEMTfKe12YWLxT5Iz9X1fbGgcF4fkJ0nHYTfYVz+\n rvWjAMQhFx+hJ0WhCMJJG8ZcAbztLny7VXl96ngOrf1VrbLj3kbu33kpHiuIqF5J", "X-Gm-Gg": "ATEYQzzQ4t8aIOAkFz738rcr9vkFgE/10mcBMZ6Y5u6/UuZutW32YQ0QIC92zbn9dwI\n KUMMseZYJEEiz3MPYoVmio5+TZKwswP73lwPqg3GDkPftL/oTgXWrega7x7uBunZa7z0jJwCDDL\n zXjE8cynsCIUpnDFpZ2EeXGOc4s5sAXAyc7OqIVQz7U3wxIZ/veDkvdotTtIpQCMdJE1aGnCV16\n BNR/fj5mpC3vkusjpnp9G1lO8HvckunLWaztqkqoQEi2Mt7DnEz4hfeou7uGMztF4zNlg3hHdPa\n nvkmC93jD0Fq6DftRRDbhPEDUJ88YNU2YM/ukpvGWgUoNHpyAN6g+LtiHD1T/3vexWksdysHvZ0\n eNT/JLw+gV6RwdPFzRYS9kD4eOMXpo7b+JlfcOv1jFF+WbD9H4HAAsr1GB5NBmDV5R3hEwHvuty\n fn/3I+civQtCQhUzFL8WmifhIUdLV5xnrjqh+v6B/kkG7m1Q==", "X-Received": "by 2002:a05:6512:33c7:b0:5a2:b2e1:39fa with SMTP id\n 2adb3069b0e04-5a2b2e13a66mr2650137e87.12.1774898822793;\n Mon, 30 Mar 2026 12:27:02 -0700 (PDT)", "From": "Max Makarov <maxpain177@gmail.com>", "X-Google-Original-From": "Max Makarov <maxpain@linux.com>", "To": "qemu-devel@nongnu.org", "Cc": "qemu-block@nongnu.org, Coiby Xu <Coiby.Xu@gmail.com>,\n Stefano Garzarella <sgarzare@redhat.com>,\n \"Michael S . Tsirkin\" <mst@redhat.com>, Kevin Wolf <kwolf@redhat.com>,\n Hanna Reitz <hreitz@redhat.com>, Max Makarov <maxpain@linux.com>", "Subject": "[PATCH] vhost-user-blk-server: fix opt_io_size=1 causing severe\n Windows I/O degradation", "Date": "Mon, 30 Mar 2026 22:27:01 +0300", "Message-ID": "<20260330192701.75780-1-maxpain@linux.com>", "X-Mailer": "git-send-email 2.50.1", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Received-SPF": "pass client-ip=2a00:1450:4864:20::134;\n envelope-from=maxpain177@gmail.com; helo=mail-lf1-x134.google.com", "X-Spam_score_int": "-17", "X-Spam_score": "-1.8", "X-Spam_bar": "-", "X-Spam_report": "(-1.8 / 5.0 requ) BAYES_00=-1.9, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1,\n FREEMAIL_ENVFROM_END_DIGIT=0.25, FREEMAIL_FROM=0.001,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n 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": "qemu development <qemu-devel.nongnu.org>", "List-Unsubscribe": "<https://lists.nongnu.org/mailman/options/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=unsubscribe>", "List-Archive": "<https://lists.nongnu.org/archive/html/qemu-devel>", "List-Post": "<mailto:qemu-devel@nongnu.org>", "List-Help": "<mailto:qemu-devel-request@nongnu.org?subject=help>", "List-Subscribe": "<https://lists.nongnu.org/mailman/listinfo/qemu-devel>,\n <mailto:qemu-devel-request@nongnu.org?subject=subscribe>", "Errors-To": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org", "Sender": "qemu-devel-bounces+incoming=patchwork.ozlabs.org@nongnu.org" }, "content": "The QSD vhost-user-blk export sets opt_io_size=1 and min_io_size=1 in\nthe virtio config. These values are reported to the guest through the\nVPD Block Limits page as OptimalTransferLength=1 block (512 bytes)\nand OptimalTransferLengthGranularity=1 block.\n\nWindows respects these hints and splits all I/O into ~512-byte\nrequests, causing ~100x sequential throughput degradation (150 MB/s\ninstead of 15+ GB/s). Linux is unaffected as its block layer ignores\nthese values.\n\nSet both to 0 which means \"not reported\" per the SCSI Block Limits\nVPD spec, allowing Windows to use its own optimal I/O size defaults.\n\nBuglink: https://github.com/spdk/spdk/issues/3199\nSigned-off-by: Max Makarov <maxpain@linux.com>\n---\n block/export/vhost-user-blk-server.c | 4 ++--\n 1 file changed, 2 insertions(+), 2 deletions(-)", "diff": "diff --git a/block/export/vhost-user-blk-server.c b/block/export/vhost-user-blk-server.c\nindex 827502d..e421f72 100644\n--- a/block/export/vhost-user-blk-server.c\n+++ b/block/export/vhost-user-blk-server.c\n@@ -242,8 +242,8 @@ vu_blk_initialize_config(BlockDriverState *bs,\n config->blk_size = cpu_to_le32(blk_size);\n config->size_max = cpu_to_le32(4096);\n config->seg_max = cpu_to_le32(128 - 2);\n- config->min_io_size = cpu_to_le16(1);\n- config->opt_io_size = cpu_to_le32(1);\n+ config->min_io_size = cpu_to_le16(0);\n+ config->opt_io_size = cpu_to_le32(0);\n config->num_queues = cpu_to_le16(num_queues);\n config->max_discard_sectors =\n cpu_to_le32(VIRTIO_BLK_MAX_DISCARD_SECTORS);\n", "prefixes": [] }