On Wed, 13 Apr 2011 09:23:11 +0800 Changli Gao <xiaosuo@xxxxxxxxx> wrote: > On Wed, Apr 13, 2011 at 6:49 AM, Andrew Morton > <akpm@xxxxxxxxxxxxxxxxxxxx> wrote: > > > > It's somewhat unclear (to me) what caused this regression. > > > > Is it because the kernel is now doing large kmalloc()s for the fdtable, > > and this makes the page allocator go nuts trying to satisfy high-order > > page allocation requests? > > > > Is it because the kernel now will usually free the fdtable > > synchronously within the rcu callback, rather than deferring this to a > > workqueue? > > > > The latter seems unlikely, so I'm thinking this was a case of > > high-order-allocations-considered-harmful? > > > > Maybe, but I am not sure. Maybe my patch causes too many inner > fragments. For example, when asking for 5 pages, get 8 pages, and 3 > pages are wasted, then memory thrash happens finally. That theory sounds less likely, but could be tested by using alloc_pages_exact(). -- 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>