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GET /api/patches/2217868/?format=api
{ "id": 2217868, "url": "http://patchwork.ozlabs.org/api/patches/2217868/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/patch/20260330193451.76037-1-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": "<20260330193451.76037-1-maxpain@linux.com>", "list_archive_url": null, "date": "2026-03-30T19:34:51", "name": "[v2] 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": "530e6e030056b645d12e31a001f8b5afb76d3c25", "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/20260330193451.76037-1-maxpain@linux.com/mbox/", "series": [ { "id": 498085, "url": "http://patchwork.ozlabs.org/api/series/498085/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=498085", "date": "2026-03-30T19:34:51", "name": "[v2] vhost-user-blk-server: fix opt_io_size=1 causing severe Windows I/O degradation", "version": 2, "mbox": "http://patchwork.ozlabs.org/series/498085/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/patches/2217868/comments/", "check": "pending", "checks": "http://patchwork.ozlabs.org/api/patches/2217868/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=R9YgtUjt;\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=1774899294; x=1775504094;\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=bftrVlRCkBO3MiDQm70utbwn7FaBGkwSQdi8+5tsnqU=;\n b=XZBDG27SCwrW173tgH4mvazoaDWdOsU2+LUhat2u6Frzfhik2Purq8k3C7a83fyEFy\n u6sFQ/CQrWmWOaEliEGLDfR86ePIt3aWxxTeVHbwjL5ikCbR6BH8U8AKOku6VnnqLbZw\n RINiXfv3NaDP2H90XDnhPSdOC11g8pn1V5wAubKQbyd98Q/jWwF3yw0FefPqNc4nYFCR\n VYcZ+hGtpP8OvUBW9ERE3NeO46MyL0qYpp0gPoK6q3ba3PC9njyWJQXJgMnzl6amF9KO\n ds/mTdaUQBlPqh2zqgN35D9QffDMWZRgU68fOHXz8dGOK3OuiIwiqf/QYpJveMG0xIgZ\n R2dQ==", "X-Gm-Message-State": "AOJu0YyUzA3ppcpyng+ALI7vOsluyEke3XMHR8ecWEVYWROZPB7wLVvq\n Ya0DbSQ+nMY+QSg3odHTesp+x29FApEtWxqI6r/mLbbO7nCbQTky9Yo3sF03ZBf+", "X-Gm-Gg": "ATEYQzwUNx6Q1BderF/bS8MUmcG0hK/AuK+tjbGWzkPQmLljSWBcd5zCnLOFJ7Zz+Qr\n +jvGLqID4jGYsj2cvEmUU8bB2McnshjMRejCpm1WTv74NeFyVmwoY3ZtT0PBM9H+uVPj1ArEGUm\n RQjQJzKxQ22j4RaMLOtDuJeH1V3MYlz0yEM9G7Cz+KgJNwFNP+Avv13N8gIiW2CkLzbziOWEBoB\n iz2kk9ekUPTiyq4yAKzvdeWy2+VcqgCs7RWivmFKUPI4F5T3jg+09Iz0OPahnQcDuRrJBbSQ/+2\n FWxaU3dzgyb5hir7UEwYWn71sXZtTrmRoldZDpcy0k5tUM/AVFWnzeG9cL0H3fIxUi3Hsyuu1VO\n fwneOhsJkT2o2MqWmbVH3HZV8Tc9h9Mlwaif4YcNb8YucK3xgSrfEElCACTeLtMnqLUSkcF5iAR\n NtY4zD5/wc3WuLMNKqtYlLO6hweo12NynSiPisYbyt3Ax9oQ==", "X-Received": "by 2002:a05:6512:6c8:b0:5a2:5b88:a8a3 with SMTP id\n 2adb3069b0e04-5a2ab92854fmr5097955e87.31.1774899293462;\n Mon, 30 Mar 2026 12:34:53 -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 v2] vhost-user-blk-server: fix opt_io_size=1 causing severe\n Windows I/O degradation", "Date": "Mon, 30 Mar 2026 22:34:51 +0300", "Message-ID": "<20260330193451.76037-1-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\nSigned-off-by: Max Makarov <maxpain@linux.com>\n---\nv2: Rebased on clean master (v1 depended on a separate size_max patch).\n Removed unrelated Buglink.\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 e89422b..67912a3 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(0);\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": [ "v2" ] }