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{ "id": 2221991, "url": "http://patchwork.ozlabs.org/api/1.1/covers/2221991/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/cover/20260410150457.85190-1-zhangckid@gmail.com/", "project": { "id": 14, "url": "http://patchwork.ozlabs.org/api/1.1/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": "" }, "msgid": "<20260410150457.85190-1-zhangckid@gmail.com>", "date": "2026-04-10T15:04:43", "name": "[V6,00/14] iothread: Support tracking and querying IOThread holders", "submitter": { "id": 72278, "url": "http://patchwork.ozlabs.org/api/1.1/people/72278/?format=api", "name": "Zhang Chen", "email": "zhangckid@gmail.com" }, "mbox": "http://patchwork.ozlabs.org/project/qemu-devel/cover/20260410150457.85190-1-zhangckid@gmail.com/mbox/", "series": [ { "id": 499477, "url": "http://patchwork.ozlabs.org/api/1.1/series/499477/?format=api", "web_url": "http://patchwork.ozlabs.org/project/qemu-devel/list/?series=499477", "date": "2026-04-10T15:04:43", "name": "iothread: Support tracking and querying IOThread holders", "version": 6, "mbox": "http://patchwork.ozlabs.org/series/499477/mbox/" } ], "comments": "http://patchwork.ozlabs.org/api/covers/2221991/comments/", "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=ZbECj9tx;\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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David Alan Gilbert\" <dave@treblig.org>,\n Eric Blake <eblake@redhat.com>, Markus Armbruster <armbru@redhat.com>,\n \"Michael S . Tsirkin\" <mst@redhat.com>,\n Stefan Hajnoczi <stefanha@redhat.com>", "Cc": "Zhang Chen <zhangckid@gmail.com>", "Subject": "[PATCH V6 00/14] iothread: Support tracking and querying IOThread\n holders", "Date": "Fri, 10 Apr 2026 23:04:43 +0800", "Message-ID": "<20260410150457.85190-1-zhangckid@gmail.com>", "X-Mailer": "git-send-email 2.49.0", "MIME-Version": "1.0", "Content-Transfer-Encoding": "8bit", "Received-SPF": "pass client-ip=2607:f8b0:4864:20::1033;\n envelope-from=zhangckid@gmail.com; helo=mail-pj1-x1033.google.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, DKIM_SIGNED=0.1,\n DKIM_VALID=-0.1, DKIM_VALID_AU=-0.1, DKIM_VALID_EF=-0.1, FREEMAIL_FROM=0.001,\n RCVD_IN_DNSWL_NONE=-0.0001, SPF_HELO_NONE=0.001,\n SPF_PASS=-0.001 autolearn=ham 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": "### Motivation\nCurrently, the relationship between IOThreads and the resources using them is\nopaque. From a management perspective, it is difficult to determine which \ndevices or block exports are currently associated with a specific IOThread \nvia QMP or HMP.\n\nThis series introduces a \"holder\" tracking mechanism based on QOM paths to \nsignificantly improve IOThread observability. In high-performance \nvirtualization environments, users often pre-allocate a set of IOThreads to \nserve as a persistent thread pool. During device hotplug/unplug cycles, while \nIOThread objects remain persistent, their attachment state changes dynamically.\n\nBy tracking these \"holders,\" administrators can use `query-iothreads` to \nmonitor the real-time load distribution of the thread pool and identify which \nspecific devices (e.g., virtio-blk, BlockExport) are attached to which thread.\n\n### Technical Overview\n* Atomic API Design: Merged iothread_get_aio_context and \n iothread_ref_and_get_aio_context into a single unified function. The new \n API enforces a 'holder' parameter, making \"retrieval\" and \"tracking\" an \n atomic operation to prevent reference tracking leaks.\n* Subsystem Integration: Fully migrated and adapted core modules including \n Virtio (blk, vq-mapping, balloon, scsi), Block Layer (export, xen), \n Network (COLO), VFIO, and the Monitor subsystem.\n* Introspection: Expanded the IOThreadInfo QAPI structure to include a \n 'holders' array (list of QOM paths), accessible via both \n query-iothreads (QMP) and info iothreads (HMP).\n\n### V5 -> V6 Changelog\n* - First of all, I apologize for spending so much time dealing with\n the background details of the code implementation.\n* API Refactoring (Breaking Change):\n - Implement the 'union': 'IoThreadHolder' for combine the QOM objects\n and the block-node.\n - Completely merged iothread_get_aio_context variants.\n - The iothread_get_aio_context function now strictly requires a 'holder' \n argument to ensure every context retrieval is accounted for.\n* Expanded Module Coverage:\n - Added holder tracking for the monitor subsystem (tracking threads used \n by QMP/HMP).\n - Added support for the virtio-scsi dataplane.\n* Code Cleanup:\n - Removed redundant and obsolete API declarations.\n - Standardized the use of object_get_canonical_path() across all callers \n to provide consistent and unique holder names.\n* Bug Fixes:\n - Updated qapi/misc.json documentation to fix missing descriptions in \n query-iothreads items.\n* Build System:\n - Improved header inclusion logic to avoid redundant declaration errors \n in unit tests.\n* QAPI part:\n - Sorry to drop the \"Acked-by: Markus Armbruster <armbru@redhat.com>\",\n because this version have lots of changes in the:\n [PATCH V6 13/14]qapi: examine IOThread attachment status via query-iothreads\n\nZhang Chen (14):\n qapi/misc: Fix missed query-iothreads items\n iothread: introduce iothread_ref/unref to track attached devices\n iothread: tracking iothread users with holder name\n blockdev: Update tracking iothread users with holder name\n block/export: track IOThread reference in BlockExport\n monitor: Update tracking iothread users with holder name\n virtio-vq-mapping: track iothread-vq-mapping references using device\n path\n virtio: use iothread_get/put_aio_context for thread pinning\n net/colo: track IOThread references using path-based holder\n virtio-balloon: Update tracking iothread users with holder name\n vfio-user/proxy: Update tracking iothread users with holder name\n xen-block: Update tracking iothread users with holder name\n qapi: examine IOThread attachment status via query-iothreads\n iothread: simplify API by merging iothread_get_aio_context variants\n\n block/export/export.c | 44 +++++++---\n blockdev.c | 6 +-\n hw/block/dataplane/xen-block.c | 10 ++-\n hw/block/virtio-blk.c | 13 ++-\n hw/scsi/virtio-scsi-dataplane.c | 13 ++-\n hw/vfio-user/proxy.c | 7 +-\n hw/virtio/iothread-vq-mapping.c | 11 ++-\n hw/virtio/virtio-balloon.c | 14 ++--\n include/block/block_int-common.h | 5 ++\n include/block/export.h | 6 ++\n include/hw/virtio/iothread-vq-mapping.h | 6 +-\n include/system/iothread.h | 5 +-\n iothread.c | 102 +++++++++++++++++++++++-\n monitor/hmp-cmds.c | 22 +++++\n monitor/monitor-internal.h | 3 +\n monitor/monitor.c | 24 +++++-\n monitor/qmp.c | 3 +-\n net/colo-compare.c | 18 +++--\n qapi/misc.json | 72 ++++++++++++++++-\n 19 files changed, 328 insertions(+), 56 deletions(-)" }