>>> Why? >> >> Otherwise, we don't have good PCP dropping trigger. Big machine might have >> big pcp cache. >> > > Big machines also have a large cost for sending IPIs. Yes. But it's only matter if IPIs are frequently happen. But, drain_all_pages() is NOT only IPI source. some vmscan function (e.g. try_to_umap) makes a lot of IPIs. Then, it's _relatively_ not costly. I have a question. Do you compare which operation and drain_all_pages()? IOW, your "costly" mean which scenario suspect? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxxx For more info on Linux MM, see: http://www.linux-mm.org/ . Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/ Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>