[lkml]   [2001]   [Jun]   [9]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [patch] truncate_inode_pages

> takes 45 seconds CPU time due to the O(clean * dirty) algorithm in
> truncate_inode_pages(). The machine is locked up for the duration.
> The patch reduces this to 20 milliseconds via an O(clean + dirty)
> algorithm.

Unfortunately, it's _not_ O(clean + dirty).

> + while (truncate_list_pages(&mapping->clean_pages, start, &partial)) {
> + spin_lock(&pagecache_lock);
> + complete = 0;
> + }

Cool. Now think what happens if pages with large indices are in the
very end of list. Half of them. You skip clean/2 pages on each of
clean/2 passes. Hardly a linear behaviour - all you need is a different
program to trigger it.

Now, having a separate pass that would reorder the pages on list,
moving the to-kill ones in the beginning might help.

To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to
More majordomo info at
Please read the FAQ at

 \ /
  Last update: 2005-03-22 12:55    [W:0.048 / U:0.196 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site