On Wed, 8 May 2013, Mel Gorman wrote: > 1. IRQs do not have to be disabled to access the lists reducing IRQs > disabled times. The per cpu structure access also would not need to disable irq if the fast path would be using this_cpu ops. > 2. As the list is protected by a spinlock, it is not necessary to > send IPI to drain the list. As the lists are accessible by multiple CPUs, > it is easier to tune. The lists are a problem since traversing list heads creates a lot of pressure on the processor and TLB caches. Could we either move to an array of pointers to page structs (like in SLAB) or to a linked list that is constrained within physical boundaries like within a PMD? (comparable to the SLUB approach)? > > 3. The magazine_lock is potentially hot but it can be split to have > one lock per CPU socket to reduce contention. Draining the lists > in this case would acquire multiple locks be acquired. IMHO the use of per cpu RMV operations would be lower latency than the use of spinlocks. There is no "lock" prefix overhead with those. Page allocation is a frequent operation that I would think needs to be as fast as possible. -- 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>