From: Yoav Cohen <yoav@nvidia.com>
To: Ming Lei <ming.lei@redhat.com>, Jens Axboe <axboe@kernel.dk>,
<linux-block@vger.kernel.org>, <csander@purestorage.com>
Cc: <jholzman@nvidia.com>, <omril@nvidia.com>
Subject: [PATCH 0/2] ublk: complete requests via blk_mq_complete_request() so rq_affinity applies
Date: Tue, 6 Oct 2026 11:55:15 +0300 [thread overview]
Message-ID: <20261006085517.33974-1-yoav@nvidia.com> (raw)
ublk ends successfully completed requests inline on the server thread,
so rq_affinity never redirects completion work back to the submitting
CPU the way it does for NVMe, SCSI, virtio-blk, loop, nbd and rnbd.
Patch 1 fixes that and adds a feature flag so servers can detect
support. Patch 2 adds a selftest for it.
With an SPDK-style polling user-space block server at queue depth 96,
rq_affinity=2 gives 7-8% higher IOPS than today's always-inline
completion by offloading a saturated server CPU; rq_affinity=0 keeps
the old behavior for anyone who wants to opt out.
Yoav Cohen (2):
ublk: complete requests via blk_mq_complete_request() so rq_affinity
applies
selftests: ublk: add test for rq_affinity completion redirection
drivers/block/ublk_drv.c | 72 +++++++++++++++++--------
include/uapi/linux/ublk_cmd.h | 8 +++
tools/testing/selftests/ublk/Makefile | 1 +
tools/testing/selftests/ublk/kublk.c | 1 +
tools/testing/selftests/ublk/test_generic_18.sh | 42 +++++++++++++++
5 files changed, 103 insertions(+), 21 deletions(-)
create mode 100755 tools/testing/selftests/ublk/test_generic_18.sh
--
2.50.1 (Apple Git-155)
next reply other threads:[~2026-10-06 8:55 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-10-06 8:55 Yoav Cohen [this message]
2026-10-06 8:55 ` [PATCH 1/2] ublk: complete requests via blk_mq_complete_request() so rq_affinity applies Yoav Cohen
2026-10-06 14:56 ` Ming Lei
2026-10-06 8:55 ` [PATCH 2/2] selftests: ublk: add test for rq_affinity completion redirection Yoav Cohen
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