From: David Sterba <dsterba@suse.cz>
To: Qu Wenruo <wqu@suse.com>
Cc: linux-btrfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH 2/4] btrfs: cache max and min order inside btrfs_fs_info
Date: Mon, 1 Sep 2025 20:10:57 +0200 [thread overview]
Message-ID: <20250901181057.GD5333@twin.jikos.cz> (raw)
In-Reply-To: <d1a3793b551f0a6ccaf8907cc5aa06d8f5b3d5c2.1756703958.git.wqu@suse.com>
On Mon, Sep 01, 2025 at 02:54:04PM +0930, Qu Wenruo wrote:
> Inside btrfs_fs_info we cache several bits shift like sectorsize_bits.
>
> Apply this to max and min folio orders so that every time mapping order
> needs to be applied we can skip the calculation.
>
> Furthermore all those sectorsize/nodesize shifts, along with the new
> min/max folio orders have a very limited value range by their natures.
>
> E.g. blocksize bits can be at most ilog2(64K) which is 16, and for 4K
> page size and 64K block size (bs > ps) the minimal folio order is only
> 4.
> Neither those number can even exceed U8_MAX, thus there is no need to
> use u32 for those bits.
>
> Use u8 for those members to save memory.
The reason for u32 is that it generates a bit better assembly code, we
don't have to save each byte in fs_info so please keep it u32.
next prev parent reply other threads:[~2025-09-01 18:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-09-01 5:24 [PATCH 0/4] btrfs: bs > ps support preparation Qu Wenruo
2025-09-01 5:24 ` [PATCH 1/4] btrfs: support all block sizes which is no larger than page size Qu Wenruo
2025-09-01 5:24 ` [PATCH 2/4] btrfs: cache max and min order inside btrfs_fs_info Qu Wenruo
2025-09-01 18:10 ` David Sterba [this message]
2025-09-02 3:46 ` kernel test robot
2025-09-01 5:24 ` [PATCH 3/4] btrfs: replace single page bio_iter_iovec() usage Qu Wenruo
2025-09-01 6:25 ` Qu Wenruo
2025-09-01 5:24 ` [PATCH 4/4] btrfs: replace bio_for_each_segment usage Qu Wenruo
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