On Tue, May 12, 2015 at 10:36:40AM +0200, Vlastimil Babka wrote: > On 04/27/2015 09:23 AM, Joonsoo Kim wrote: > >Sometimes we try to get more freepages from buddy list than how much > >we really need, in order to refill pcp list. This may speed up following > >allocation request, but, there is a possibility to increase fragmentation > >if we steal freepages from other migratetype buddy list excessively. This > >patch changes this behaviour to stop fallback allocation in order to > >reduce fragmentation if we already get some freepages. > > > >CPU: 8 > >RAM: 512 MB with zram swap > >WORKLOAD: kernel build with -j12 > >OPTION: page owner is enabled to measure fragmentation > >After finishing the build, check fragmentation by 'cat /proc/pagetypeinfo' > > > >* Before > >Number of blocks type (movable) > >DMA32: 208.4 > > > >Number of mixed blocks (movable) > >DMA32: 139 > > > >Mixed blocks means that there is one or more allocated page for > >unmovable/reclaimable allocation in movable pageblock. Results shows that > >more than half of movable pageblock is tainted by other migratetype > >allocation. > > > >* After > >Number of blocks type (movable) > >DMA32: 207 > > > >Number of mixed blocks (movable) > >DMA32: 111.2 > > > >This result shows that non-mixed block increase by 38% in this case. > > > >Signed-off-by: Joonsoo Kim <iamjoonsoo....@lge.com> > > I agree that keeping fragmentation low is more important than > filling up the pcplists. Wouldn't expect such large difference > though. Are the results stable?
Yes, I think that improvement is very stable. stdev is roughly 8 in 5 runs. Thanks. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
