On 07/31/2015 02:30 AM, Xishi Qiu wrote: > __free_one_page() will judge whether the the next-highest order is free, > then add the block to the tail or not. So when we split large order block, > add the small block to the tail, it will reduce fragment. It's an interesting idea, but what does it do in practice? Can you measure a decrease in fragmentation? Further, the comment above the function says: * The order of subdivision here is critical for the IO subsystem. * Please do not alter this order without good reasons and regression * testing. Has there been regression testing? Also, this might not do very much good in practice. If you are splitting a high-order page, you are doing the split because the lower-order lists are empty. So won't that list_add() be to an empty list most of the time? Or does the __rmqueue_fallback() largest->smallest logic dominate? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>