On 07/22/2012 10:33 PM, Minchan Kim wrote:
IMHO, better approach is that after we can get complete free pageblocks by compaction or reclaim, move balloon pages into that pageblocks and make that blocks to unmovable. It can prevent fragmentation and it makes current or future code don't need to consider balloon page.
I believe this is the wrong thing to do. In a KVM guest, getting applications in transparent huge pages can be a 10-25% performance benefit. Therefore, we need to make all the 2MB pageblocks we can available for use by userland. Using 2MB blocks for the balloon (which is never touched) is extremely wasteful and could result in a large performance penalty, if we cannot defragment the remaining memory enough to give 2MB pages to applications. The 2MB blocks are prime real estate. They should remain available for applications. -- 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>