From: Ming Lei <ming.lei@redhat.com>
To: Caleb Sander Mateos <csander@purestorage.com>
Cc: Jens Axboe <axboe@kernel.dk>,
Uday Shankar <ushankar@purestorage.com>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH 8/8] ublk: store request pointer in ublk_io
Date: Sun, 27 Apr 2025 21:25:24 +0800 [thread overview]
Message-ID: <aA4wROulY-gMJFqS@fedora> (raw)
In-Reply-To: <20250427045803.772972-9-csander@purestorage.com>
On Sat, Apr 26, 2025 at 10:58:03PM -0600, Caleb Sander Mateos wrote:
> A ublk_io is converted to a request in several places in the I/O path by
> looking up the (qid, tag) on the ublk device's tagset. This involves a
> bunch of pointer dereferences and a bounds check of the tag.
>
> To make this conversion cheaper, store the request pointer in ublk_io.
> Overlap this storage with the io_uring_cmd pointer. This is safe because
> the io_uring_cmd pointer is only valid if UBLK_IO_FLAG_ACTIVE is set on
> the ublk_io, the request pointer is valid if UBLK_IO_FLAG_OWNED_BY_SRV,
> and these flags are mutually exclusive.
Yeah, it becomes exclusive after UBLK_IO_NEED_GET_DATA is cleaned as one
sync command.
>
> Suggested-by: Ming Lei <ming.lei@redhat.com>
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
thanks,
Ming
prev parent reply other threads:[~2025-04-27 13:25 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-04-27 4:57 [PATCH 0/8] ublk: simplify NEED_GET_DATA handling and request lookup Caleb Sander Mateos
2025-04-27 4:57 ` [PATCH 1/8] ublk: factor out ublk_commit_and_fetch Caleb Sander Mateos
2025-04-27 4:57 ` [PATCH 2/8] ublk: fix "immepdately" typo in comment Caleb Sander Mateos
2025-04-27 12:58 ` Ming Lei
2025-04-27 4:57 ` [PATCH 3/8] ublk: remove misleading "ubq" in "ubq_complete_io_cmd()" Caleb Sander Mateos
2025-04-27 13:01 ` Ming Lei
2025-04-27 4:57 ` [PATCH 4/8] ublk: don't log uring_cmd cmd_op in ublk_dispatch_req() Caleb Sander Mateos
2025-04-27 13:03 ` Ming Lei
2025-04-27 4:58 ` [PATCH 5/8] ublk: factor out ublk_start_io() helper Caleb Sander Mateos
2025-04-27 13:05 ` Ming Lei
2025-04-28 14:28 ` Caleb Sander Mateos
2025-04-28 15:12 ` Caleb Sander Mateos
2025-04-29 4:05 ` Ming Lei
2025-04-29 14:55 ` Caleb Sander Mateos
2025-04-30 22:44 ` Caleb Sander Mateos
2025-04-27 4:58 ` [PATCH 6/8] ublk: don't call ublk_dispatch_req() for NEED_GET_DATA Caleb Sander Mateos
2025-04-27 13:10 ` Ming Lei
2025-04-27 4:58 ` [PATCH 7/8] ublk: check UBLK_IO_FLAG_OWNED_BY_SRV in ublk_abort_queue() Caleb Sander Mateos
2025-04-27 13:13 ` Ming Lei
2025-04-27 4:58 ` [PATCH 8/8] ublk: store request pointer in ublk_io Caleb Sander Mateos
2025-04-27 13:25 ` Ming Lei [this message]
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