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From: Bart Van Assche <bvanassche@acm.org>
To: John Garry <john.g.garry@oracle.com>,
	Andreas Hindborg <a.hindborg@kernel.org>
Cc: Jens Axboe <axboe@kernel.dk>,
	Oliver Mangold <oliver.mangold@pm.me>,
	linux-block@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] block: set bi_vcnt when cloning bio
Date: Tue, 18 Feb 2025 14:21:52 -0800	[thread overview]
Message-ID: <6c3d81f0-aee5-4619-82c4-3ce72bdce317@acm.org> (raw)
In-Reply-To: <464bc3f5-aef2-4e6b-b7cb-035077d1e3f4@oracle.com>

On 2/18/25 9:12 AM, John Garry wrote:
> On 18/02/2025 11:40, Andreas Hindborg wrote:
>> But I am genuinely curious if there is a reason for not setting
>> `bi_vcnt` during a clone.
> 
> I think that it came from commit 59d276fe0 (with the addition of 
> bio_clone_fast()), where we assume that the cloned bio is not having the 
> bio_vec touched and so does not need to know bi_vcnt (or bi_max_vecs). 
> And it is inefficient to needlessly set bi_vcnt then.

Hmm ... I prefer paying the very small performance hit caused by copying
bi_vcnt rather than having to deal with the inconsistency caused by not
copying that data structure member.

Thanks,

Bart.

  parent reply	other threads:[~2025-02-18 22:24 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2025-02-15 10:58 Andreas Hindborg
2025-02-18 10:40 ` John Garry
2025-02-18 11:40   ` Andreas Hindborg
2025-02-18 17:12     ` John Garry
2025-02-18 18:20       ` Andreas Hindborg
2025-02-18 22:21       ` Bart Van Assche [this message]
2025-02-19 14:19         ` John Garry
2025-02-20  6:11 ` Christoph Hellwig

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