From: Jens Axboe <axboe@kernel.dk>
To: Ming Lei <ming.lei@redhat.com>
Cc: linux-block@vger.kernel.org, Martin Wilck <martin.wilck@suse.com>
Subject: Re: [PATCH] lib/sbitmap: kill 'depth' from sbitmap_word
Date: Sun, 9 Jan 2022 18:54:21 -0700 [thread overview]
Message-ID: <020ba538-bb41-c827-1290-c2939bf8940c@kernel.dk> (raw)
In-Reply-To: <20220110015007.326561-1-ming.lei@redhat.com>
On 1/9/22 6:50 PM, Ming Lei wrote:
> Only the last sbitmap_word can have different depth, and all the others
> must have same depth of 1U << sb->shift, so not necessary to store it in
> sbitmap_word, and it can be retrieved easily and efficiently by adding
> one internal helper of __map_depth(sb, index).
>
> Not see performance effect when running iops test on null_blk.
>
> This way saves us one cacheline(usually 64 words) per each sbitmap_word.
We probably want to kill the ____cacheline_aligned_in_smp from 'word' as
well.
--
Jens Axboe
next prev parent reply other threads:[~2022-01-10 1:54 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-01-10 1:50 [PATCH] lib/sbitmap: kill 'depth' from sbitmap_word Ming Lei
2022-01-10 1:54 ` Jens Axboe [this message]
2022-01-10 2:38 ` Ming Lei
2022-01-10 2:43 ` Jens Axboe
2022-01-10 2:47 ` Ming Lei
2022-01-10 2:49 ` Jens Axboe
2022-01-10 16:22 ` Martin Wilck
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