On Tue, Oct 23, 2012 at 09:41:00AM -0400, Rik van Riel wrote: > On 10/23/2012 01:51 AM, Shaohua Li wrote: > > >I have no strong point against the global state method. But I'd agree making the > >heuristic simple is preferred currently. I'm happy about the patch if the '+1' > >is removed. > > Without the +1, how will you figure out when to re-enable readahead? Below code in swapin_nr_pages can recover it. + if (offset == prev_offset + 1 || offset == prev_offset - 1) + pages <<= 1; Not perfect, but should work in some sort. This reminds me to think if pagereadahead flag is really required, hit in swap cache is a more reliable way to count readahead hit, and as Hugh mentioned, swap isn't vma bound. Thanks, Shaohua -- 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>