From: Christoph Hellwig <hch@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Luis Chamberlain <mcgrof@kernel.org>,
Matthew Wilcox <willy@infradead.org>,
axboe@kernel.dk, agk@redhat.com, snitzer@kernel.org,
philipp.reisner@linbit.com, lars.ellenberg@linbit.com,
christoph.boehmwalder@linbit.com, hch@infradead.org,
djwong@kernel.org, minchan@kernel.org, senozhatsky@chromium.org,
patches@lists.linux.dev, linux-block@vger.kernel.org,
linux-mm@kvack.org, linux-xfs@vger.kernel.org,
linux-fsdevel@vger.kernel.org, dm-devel@redhat.com,
drbd-dev@lists.linbit.com, linux-kernel@vger.kernel.org,
hare@suse.de, p.raghav@samsung.com, da.gomez@samsung.com,
kbusch@kernel.org
Subject: Re: [PATCH 3/5] iomap: simplify iomap_init() with PAGE_SECTORS
Date: Sun, 23 Apr 2023 22:55:45 -0700 [thread overview]
Message-ID: <ZEYZ4ScVDXviFJ/J@infradead.org> (raw)
In-Reply-To: <20230421223420.GH3223426@dread.disaster.area>
On Sat, Apr 22, 2023 at 08:34:20AM +1000, Dave Chinner wrote:
> >
> > - return bioset_init(&iomap_ioend_bioset, 4 * (PAGE_SIZE / SECTOR_SIZE),
> > + return bioset_init(&iomap_ioend_bioset, 4 * PAGE_SECTORS,
>
> Yes, please.
>
> > The shift just seemed optimal if we're just going to change it.
>
> Nope, it's just premature optimisation at the expense of
> maintainability. The compiler will optimise the multiplication into
> shifts if that is the fastest way to do it for the given
> architecture the code is being compiled to.
We still had cases of the compiler not doing obvious
multiplication/division to shift conversion lately. That being said:
1) this is an initialization path, no one actually cares
2) we're dealing with constants here, and compilers are really good
at constant folding
so yes, this should be using the much more readable version.
next prev parent reply other threads:[~2023-04-24 5:55 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2023-04-21 19:58 [PATCH 0/5] block: simplify with PAGE_SECTORS_SHIFT Luis Chamberlain
2023-04-21 19:58 ` [PATCH 1/5] dm integrity: simplify by using PAGE_SECTORS_SHIFT Luis Chamberlain
2023-04-21 20:15 ` Matthew Wilcox
2023-04-21 19:58 ` [PATCH 2/5] drbd: use PAGE_SECTORS_SHIFT and PAGE_SECTORS Luis Chamberlain
2023-04-24 8:26 ` Christoph Böhmwalder
2023-04-21 19:58 ` [PATCH 3/5] iomap: simplify iomap_init() with PAGE_SECTORS Luis Chamberlain
2023-04-21 20:14 ` Matthew Wilcox
2023-04-21 22:02 ` Luis Chamberlain
2023-04-21 22:24 ` Jens Axboe
2023-04-21 22:30 ` Luis Chamberlain
2023-04-21 22:36 ` Jens Axboe
2023-04-21 22:34 ` Dave Chinner
2023-04-24 5:55 ` Christoph Hellwig [this message]
2023-04-21 19:58 ` [PATCH 4/5] dm bufio: simplify by using PAGE_SECTORS_SHIFT Luis Chamberlain
2023-04-21 19:58 ` [PATCH 5/5] zram: use generic PAGE_SECTORS and PAGE_SECTORS_SHIFT Luis Chamberlain
2023-04-24 2:36 ` Sergey Senozhatsky
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