From: Matthew Wilcox <willy@infradead.org>
To: Christopher Lameter <cl@linux.com>
Cc: Dave Chinner <dchinner@redhat.com>,
linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
Christoph Hellwig <hch@lst.de>, Mel Gorman <mel@skynet.ie>,
Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [RFC] Heuristic for inode/dentry fragmentation prevention
Date: Wed, 3 Jan 2018 12:33:03 -0800 [thread overview]
Message-ID: <20180103203303.GA3228@bombadil.infradead.org> (raw)
In-Reply-To: <alpine.DEB.2.20.1801031332230.10522@nuc-kabylake>
On Wed, Jan 03, 2018 at 01:39:27PM -0600, Christopher Lameter wrote:
> +/* How many objects left in slab page */
> +unsigned kobjects_left_in_slab_page(const void *object)
> +{
> + struct page *page;
> +
> + if (unlikely(ZERO_OR_NULL_PTR(object)))
> + return 0;
> +
> + page = virt_to_head_page(object);
> +
> + if (unlikely(!PageSlab(page))) {
> + WARN_ON(1);
> + return 1;
> + }
I see this construct all over the kernel. Here's a better one:
if (WARN_ON(!PageSlab(page)))
return 1;
There's a built-in unlikely() in the definition of WARN_ON, so this
works nicely.
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next prev parent reply other threads:[~2018-01-03 20:33 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-03 19:39 Christopher Lameter
2018-01-03 20:33 ` Matthew Wilcox [this message]
2018-01-03 21:06 ` Matthew Wilcox
2018-01-04 0:08 ` Dave Chinner
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