linux-kernel - Re: [PATCH v2] iov_iter: streamline iovec/bvec alignment iteration

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Message-ID: <ZbErQX4Z1pD0aa_5@kbusch-mbp.dhcp.thefacebook.com>
Date: Wed, 24 Jan 2024 08:22:41 -0700
From: Keith Busch <kbusch@...nel.org>
To: Jens Axboe <axboe@...nel.dk>
Cc: LKML <linux-kernel@...r.kernel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>,
	Christian Brauner <brauner@...nel.org>
Subject: Re: [PATCH v2] iov_iter: streamline iovec/bvec alignment iteration

On Tue, Jan 23, 2024 at 03:24:46PM -0700, Jens Axboe wrote:
> Rewrite the alignment checking iterators for iovec and bvec to be easier
> to read, and also significantly more compact in terms of generated code.
> This saves 270 bytes of text on x86-64 for me (with clang-18) and 224
> bytes on arm64 (with gcc-13).
> 
> In profiles, also saves a bit of time as well for the same workload:
> 
>      0.81%     -0.18%  [kernel.vmlinux]  [k] iov_iter_aligned_bvec
>      0.48%     -0.09%  [kernel.vmlinux]  [k] iov_iter_is_aligned
> 
> which is a nice side benefit as well.

Looks good

Reviewed-by: Keith Busch <kbusch@...nel.org>