On Mon, Jun 06, 2011 at 02:38:51PM +0200, Andrea Arcangeli wrote: > On Mon, Jun 06, 2011 at 11:39:24AM +0100, Mel Gorman wrote: > > Well spotted. > > > > Acked-by: Mel Gorman <[email protected]> > > > > Minor nit. swapper_space is rarely referred to outside of the swap > > code. Might it be more readable to use > > > > /* > > * swapcache is accounted as NR_FILE_PAGES but it is not > > * accounted as NR_SHMEM > > * > > if (PageSwapBacked(page) && !PageSwapCache(page)) > > I thought the comparison on swapper_space would be faster as it was > immediate vs register in CPU, instead of forcing a memory > access. Otherwise I would have used the above. Now the test_bit is > written in C and lockless so it's not likely to be very different > considering the cacheline is hot in the CPU but it's still referencing > memory instead register vs immediate comparison.
Ok, I had not considered that. That is a micro-optimisation but it's there. I thought my version is more readable and migration is not really a fast path but yours is still better. -- Mel Gorman SUSE Labs _______________________________________________ stable mailing list [email protected] http://linux.kernel.org/mailman/listinfo/stable
