On Sun, 18 Mar 2007 19:05:41 +0000 (GMT) Mel Gorman <[EMAIL PROTECTED]> wrote:
> > How much additional memory consumption are we expecting here? > > > > Short answer, about 1.5KB on a 1GB system of which 1.3KB is statically > defined in the 3 struct zones on a 1 node x86 system. > > Longer answer that I hopefully have not made any mistakes in - There is > the zone overhead which is statically sized and a runtime overhead which > depends on the amount of memory in the system. The additional zone > overhead is the overhead for additional freelists (larger struct > free_area) and is as follows; > > (MIGRATE_TYPES-1) * sizeof(list_head) * (MAX_ORDER-1) > > so, on 32 bit in general, thats > > 4 * 8 * 10 = 320 bytes per zone (would be 240 bytes if MIGRATE_RESERVE is > sufficient for higher order allocations > instead of MIGRATE_HIGHALLOC) > > on x86 with DMA, Normal and HighMem, thats 1280 bytes. On a NUMA system, > it's 1280 bytes per node. On 64 bit, it would be double because of the > larger pointer size. At worst, I guess you are looking at 3KB per node. That a very modest overhead - not worth the config option, IMO. The runtime overhead might be a concern - is it possible to quantify it? - 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/
