On Thu, Jun 23, 2011 at 08:10:47AM -0400, Theodore Tso wrote:

On Jun 23, 2011, at 2:36 AM, Andrea Righi wrote:

quoted

With the following solution when posix_fadvise(POSIX_FADV_DONTNEED) is
called for an active page instead of removing it from the page cache it
is added to the tail of the inactive list. Otherwise, if it's already in
the inactive list the page is removed from the page cache.

Have you thought about this heuristic?   If the page is active, try to
remove it from the current process's page table.  If that drops the
use count of the page to zero, then drop it from the page cache;
otherwise, leave it alone.

That way, if the page is being used by anyone else, we don't touch
the page at all.   fadvise() should only affect the current process; if
it's available to non-root users, it shouldn't be affecting other
processes, and if it is being actively used by some other process,
removing it from their page tables so it can be put on the inactive
list counts as interference, doesn't it?

If the page is mapped in other process page tables we don't touch the
page at all (see lru_deactivate_fn in mm/swap.c).

So the heuristic above it's already implemented. I should have said this
explicitly in my description...

-Andrea

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  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@kvack.org"> email@kvack.org </a>