From: Matthew Wilcox <willy@infradead.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, David Rientjes <rientjes@google.com>,
Christoph Lameter <cl@linux.com>,
Hyeonggon Yoo <42.hyeyoo@gmail.com>,
Roman Gushchin <roman.gushchin@linux.dev>,
Kees Cook <keescook@chromium.org>,
Alice Ryhl <aliceryhl@google.com>,
Boqun Feng <boqun.feng@gmail.com>,
rust-for-linux@vger.kernel.org, linux-kernel@vger.kernel.org,
patches@lists.linux.dev
Subject: Re: [PATCH v2] slab, rust: extend kmalloc() alignment guarantees to remove Rust padding
Date: Wed, 3 Jul 2024 13:32:31 +0100 [thread overview]
Message-ID: <ZoVE34S2fOyUdZYg@casper.infradead.org> (raw)
In-Reply-To: <20240703072520.45837-2-vbabka@suse.cz>
On Wed, Jul 03, 2024 at 09:25:21AM +0200, Vlastimil Babka wrote:
> - if (is_power_of_2(size))
> - align = max(align, size);
> + if (flags & SLAB_KMALLOC)
> + align = max(align, 1U << (ffs(size) - 1));
hmm ... maybe this would be faster:
if (flags & SLAB_KMALLOC) {
u32 tmp = size & (size - 1);
align = max(align, size - tmp);
}
(if size is 2^n, tmp is 0. otherwise, tmp is size with the lowest bit
clear, so size-tmp is the largest POT that divides size evenly)
next prev parent reply other threads:[~2024-07-03 12:32 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-07-03 7:25 Vlastimil Babka
2024-07-03 8:12 ` Alice Ryhl
2024-07-03 12:32 ` Matthew Wilcox [this message]
2024-07-03 12:57 ` Vlastimil Babka
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