On (09/08/07 18:44), Christoph Lameter didst pronounce: > > On Fri, 10 Aug 2007, Mel Gorman wrote: > > > > > +#if defined(CONFIG_SMP) && INTERNODE_CACHE_SHIFT > ZONES_SHIFT > > > > > > Is this necessary? ZONES_SHIFT is always <= 2 so it will work with > > > any pointer. Why disable this for UP? > > > > > > > Caution in case the number of zones increases. There was no guarantee of > > zone alignment. It's the same reason I have a BUG_ON in the encode > > function so that if we don't catch problems at compile-time, it'll go > > BANG in a nice predictable fashion. > > Caution would lead to a BUG_ON but why the #if? Why exclude UP?
On x86_64 would have ZONE_DMA, ZONE_DMA32, ZONE_NORMAL, ZONE_HIGHMEM and ZONE_MOVABLE. On SMP, that's more than two bits worth and would fail t runtime. Well, it should at least I didn't actually try it out. However, I accept that the SMP check is less than than ideal. I considered comparing it against MAX_NR_ZONES but as it's an enum, it can't be checked at compile time. What else would make a better check? -- Mel Gorman Part-time Phd Student Linux Technology Center University of Limerick IBM Dublin Software Lab - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
