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Mon, 03 Aug 2026 14:14:45 -0700 (PDT) Received: from c7-smtp-2026.dev.purestorage.com ([2620:125:9017:12:36:3:6:0]) by smtp-relay.gmail.com with ESMTPS id 41be03b00d2f7-cbe39643987sm856581a12.1.2026.08.03.14.14.45 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 03 Aug 2026 14:14:45 -0700 (PDT) X-Relaying-Domain: purestorage.com Received: from dev-csander.dev.purestorage.com (bond0.slc5-n17m28-k8s.dev.purestorage.com [IPv6:2620:125:9025:20::a31:41f]) by c7-smtp-2026.dev.purestorage.com (Postfix) with ESMTP id 3561A436B7; Mon, 3 Aug 2026 15:14:45 -0600 (MDT) Received: by dev-csander.dev.purestorage.com (Postfix, from userid 1557716354) id 3213DE4041D; Mon, 3 Aug 2026 15:14:45 -0600 (MDT) From: Caleb Sander Mateos To: Ming Lei , Jens Axboe , Shuah Khan Cc: linux-block@vger.kernel.org, linux-kselftest@vger.kernel.org, linux-kernel@vger.kernel.org, Caleb Sander Mateos Subject: [PATCH v2 4/8] ublk: initialize io_desc on daemon task Date: Mon, 3 Aug 2026 15:14:36 -0600 Message-ID: <20260803211441.2538144-5-csander@purestorage.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260803211441.2538144-1-csander@purestorage.com> References: <20260803211441.2538144-1-csander@purestorage.com> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit ublk_setup_iod() is currently called to populate struct ublksrv_io_desc on the thread submitting I/O to a ublk device. However, only the ublk server threads read the io_descs. This basically guarantees a cache miss on both threads for each ublk I/O. There's really no need to initialize the io_descs on the submitting thread. Move the ublk_setup_iod() call to ublk_dispatch_req() (for non-UBLK_F_BATCH_IO) and __ublk_batch_prep_dispatch() (for UBLK_F_BATCH_IO), which runs on the ublk server daemon thread before dispatching the I/O to userspace. Signed-off-by: Caleb Sander Mateos Reviewed-by: Ming Lei --- drivers/block/ublk_drv.c | 3 ++- 1 file changed, 2 insertions(+), 1 deletion(-) diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c index 7f0549238d76..291461e1b236 100644 --- a/drivers/block/ublk_drv.c +++ b/drivers/block/ublk_drv.c @@ -1798,10 +1798,11 @@ static void ublk_dispatch_req(struct ublk_queue *ubq, struct request *req) { unsigned int issue_flags = IO_URING_CMD_TASK_WORK_ISSUE_FLAGS; u16 tag = req->tag; struct ublk_io *io = &ubq->ios[tag]; + ublk_setup_iod(ubq, req); pr_devel("%s: complete: qid %d tag %d io_flags %x addr %llx\n", __func__, ubq->q_id, req->tag, io->flags, ublk_get_iod(ubq, req->tag)->addr); /* @@ -1851,10 +1852,11 @@ static bool __ublk_batch_prep_dispatch(struct ublk_queue *ubq, struct ublk_io *io = &ubq->ios[tag]; struct request *req = blk_mq_tag_to_rq(ub->tag_set.tags[ubq->q_id], tag); enum auto_buf_reg_res res = AUTO_BUF_REG_FALLBACK; struct io_uring_cmd *cmd = data->cmd; + ublk_setup_iod(ubq, req); if (!ublk_start_io(ubq, req, io)) return false; if (ublk_support_auto_buf_reg(ubq) && blk_rq_has_data(req)) { res = ublk_auto_buf_register(ubq, req, io, cmd, @@ -2187,11 +2189,10 @@ static blk_status_t ublk_prep_req(struct ublk_queue *ubq, struct request *rq, /* fill iod to slot in io cmd buffer */ if (unlikely(!ublk_validate_req(ubq, rq))) return BLK_STS_IOERR; - ublk_setup_iod(ubq, rq); blk_mq_start_request(rq); return BLK_STS_OK; } /* -- 2.54.0