On Thu, 22 Feb 2007, Pekka J Enberg wrote: >> As suggested by William, free the actual pages in a batch so that we >> don't keep pounding on l3->list_lock.
On Thu, Feb 22, 2007 at 03:01:30PM -0800, Christoph Lameter wrote: > This means holding the l3->list_lock for a prolonged time period. The > existing code was done this way in order to make sure that the interrupt > holdoffs are minimal. > There is no pounding. The cacheline with the list_lock is typically held > until the draining is complete. While we drain the freelist we need to be > able to respond to interrupts. I had in mind something more like a list_splice_init() operation under the lock, since it empties the entire list except in the case of cache_reap(). For cache_reap(), not much could be done unless they were organized into batches of (l3->free_limit+5*searchp->num-1)/(5*searchp->num) such as a list of lists of that length, which would need to be reorganized when tuning ->batchcount occurs. It's not terribly meaningful since only grand reorganizations that are presumed to stop the world actually get "sped up" without the additional effort required to improve cache_reap(). My commentary was more about the data structures being incapable of bulk movement operations for batching like or analogous to list_splice() than trying to say that drain_freelist() in particular should be optimized. Allowing movement of larger batches without increased hold time in transfer_objects() is clearly a more meaningful goal, for example. Furthermore, the patch as written merely increases hold time in exchange for decreased arrival rate resulting in no net improvement. -- wli - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
