From: Al Viro <viro@zeniv.linux.org.uk>
To: Christoph Hellwig <hch@lst.de>
Cc: linux-fsdevel@vger.kernel.org, Yu Kuai <yukuai1@huaweicloud.com>,
linux-block@vger.kernel.org,
Christian Brauner <brauner@kernel.org>,
Jens Axboe <axboe@kernel.dk>
Subject: Re: [PATCHES][RFC] packing struct block_device flags
Date: Fri, 3 May 2024 01:06:47 +0100 [thread overview]
Message-ID: <20240503000647.GQ2118490@ZenIV> (raw)
In-Reply-To: <20240429183041.GC2118490@ZenIV>
On Mon, Apr 29, 2024 at 07:30:41PM +0100, Al Viro wrote:
> On Mon, Apr 29, 2024 at 07:13:00PM +0100, Al Viro wrote:
> > On Mon, Apr 29, 2024 at 06:02:09PM +0100, Al Viro wrote:
> > > On Mon, Apr 29, 2024 at 08:31:07AM +0100, Al Viro wrote:
> > >
> > > > FWIW, we could go for atomic_t there and use
> > > > atomic_read() & 0xff
> > > > for partno, with atomic_or()/atomic_and() for set/clear and
> > > > atomic_read() & constant for test. That might slightly optimize
> > > > set/clear on some architectures, but setting/clearing flags is
> > > > nowhere near hot enough for that to make a difference.
> > >
> > > Incremental for that (would be folded into 3/8 if we went that way)
> > > is below; again, I'm not at all sure it's idiomatic enough to bother
> > > with, but that should at least show what's going on:
> >
> > Or this, for that matter:
>
> See #work.bd_flags-2 for carve-up of that variant.
Ugh... Forgot to push it out, sorry. Branch pushed out now,
individual patches in followups.
Summary of changes compared to posted variant:
__bd_flags is atomic_t now.
atomic_{or,andnot} is used instead of cmpxchg().
the constants (BD_READ_ONLY, etc.) are masks, not flag numbers.
next prev parent reply other threads:[~2024-05-03 0:06 UTC|newest]
Thread overview: 24+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-04-28 5:12 [PATCHES][RFC] packing struct block_device flags Al Viro
2024-04-28 5:14 ` [PATCH 1/8] Use bdev_is_paritition() instead of open-coding it Al Viro
2024-04-29 5:19 ` Christoph Hellwig
2024-04-28 5:15 ` [PATCH 2/8] wrapper for access to ->bd_partno Al Viro
2024-04-28 5:16 ` [PATCH 3/8] bdev: infrastructure for flags Al Viro
2024-04-28 5:17 ` [PATCH 4/8] bdev: move ->bd_read_only to ->__bd_flags Al Viro
2024-04-28 5:18 ` [PATCH 5/8] bdev: move ->bd_write_holder into ->__bd_flags Al Viro
2024-04-28 5:19 ` [PATCH 6/8] bdev: move ->bd_has_subit_bio to ->__bd_flags Al Viro
2024-04-28 5:19 ` [PATCH 7/8] bdev: move ->bd_ro_warned " Al Viro
2024-04-28 5:21 ` [PATCH 8/8] bdev: move ->bd_make_it_fail " Al Viro
2024-04-29 5:23 ` [PATCHES][RFC] packing struct block_device flags Christoph Hellwig
2024-04-29 7:31 ` Al Viro
2024-04-29 17:02 ` Al Viro
2024-04-29 18:13 ` Al Viro
2024-04-29 18:30 ` Al Viro
2024-05-03 0:06 ` Al Viro [this message]
2024-05-03 0:07 ` [PATCH 1/8] Use bdev_is_paritition() instead of open-coding it Al Viro
2024-05-03 0:07 ` [PATCH 2/8] wrapper for access to ->bd_partno Al Viro
2024-05-03 0:08 ` [PATCH v2 3/8] bdev: infrastructure for flags Al Viro
2024-05-03 0:09 ` [PATCH v2 4/8] bdev: move ->bd_read_only to ->__bd_flags Al Viro
2024-05-03 0:09 ` [PATCH v2 5/8] bdev: move ->bd_write_holder into ->__bd_flags Al Viro
2024-05-03 0:10 ` [PATCH v2 6/8] bdev: move ->bd_has_subit_bio to ->__bd_flags Al Viro
2024-05-03 0:10 ` [PATCH v2 7/8] bdev: move ->bd_ro_warned " Al Viro
2024-05-03 0:11 ` [PATCH v2 8/8] bdev: move ->bd_make_it_fail " Al Viro
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