From: Nikita Danilov <nikita@clusterfs.com>
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Date: Thu, 9 Feb 2006 21:04:47 +0300
To: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>,
       ck list <ck@vds.kolivas.org>, linux-mm@kvack.org,
       Nick Piggin <npiggin@suse.de>, Paul Jackson <pj@sgi.com>
Subject: Re: [PATCH] mm: Implement Swap Prefetching v22
Newsgroups: gmane.linux.kernel,gmane.linux.kernel.ck,gmane.linux.kernel.mm
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	<43EB43B9.5040001@yahoo.com.au>
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Nick Piggin writes:

[...]

 > > +/*
 > > + * We check to see no part of the vm is busy. If it is this will interrupt
 > > + * trickle_swap and wait another PREFETCH_DELAY. Purposefully racy.
 > > + */
 > > +inline void delay_swap_prefetch(void)
 > > +{
 > > +	__set_bit(0, &swapped.busy);
 > > +}
 > > +
 > 
 > Test this first so you don't bounce the cacheline around in page
 > reclaim too much.

Shouldn't we have special macros/inlines for this? Like, e.g.,

static inline void __set_bit_weak(int nr, volatile unsigned long * addr)
{
        if (!__test_bit(nr, addr))
                __set_bit(nr, addr);
}

? These test-then-set sequences start to proliferate throughout the code.

[...]

Nikita.
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