From: Ming Lei <ming.lei@redhat.com>
To: Caleb Sander Mateos <csander@purestorage.com>
Cc: Jens Axboe <axboe@kernel.dk>,
linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 1/2] ublk: use copy_{to,from}_iter() for user copy
Date: Thu, 6 Nov 2025 12:22:52 +0800 [thread overview]
Message-ID: <aQwinGy55Bk0r-LU@fedora> (raw)
In-Reply-To: <20251105202823.2198194-2-csander@purestorage.com>
On Wed, Nov 05, 2025 at 01:28:22PM -0700, Caleb Sander Mateos wrote:
> ublk_copy_user_pages()/ublk_copy_io_pages() currently uses
> iov_iter_get_pages2() to extract the pages from the iov_iter and
> memcpy()s between the bvec_iter and the iov_iter's pages one at a time.
> Switch to using copy_to_iter()/copy_from_iter() instead. This avoids the
> user page reference count increments and decrements and needing to split
> the memcpy() at user page boundaries. It also simplifies the code
> considerably.
> Ming reports a 40% throughput improvement when issuing I/O to the
> selftests null ublk server with zero-copy disabled.
>
> Signed-off-by: Caleb Sander Mateos <csander@purestorage.com>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Thanks,
Ming
next prev parent reply other threads:[~2025-11-06 4:23 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-11-05 20:28 [PATCH v2 0/2] ublk: simplify user copy Caleb Sander Mateos
2025-11-05 20:28 ` [PATCH v2 1/2] ublk: use copy_{to,from}_iter() for " Caleb Sander Mateos
2025-11-06 4:22 ` Ming Lei [this message]
2025-11-05 20:28 ` [PATCH v2 2/2] ublk: use rq_for_each_bvec() " Caleb Sander Mateos
2025-11-06 4:27 ` Ming Lei
2025-11-06 16:49 ` Caleb Sander Mateos
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