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 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/
