On 18.06.2013 06:50, Jeff Roberson wrote:
Author: jeff Date: Tue Jun 18 04:50:20 2013 New Revision: 251894 URL: http://svnweb.freebsd.org/changeset/base/251894Log: Refine UMA bucket allocation to reduce space consumption and improve performance. - Always free to the alloc bucket if there is space. This gives LIFO allocation order to improve hot-cache performance. This also allows for zones with a single bucket per-cpu rather than a pair if the entire working set fits in one bucket. - Enable per-cpu caches of buckets. To prevent recursive bucket allocation one bucket zone still has per-cpu caches disabled. - Pick the initial bucket size based on a table driven maximum size per-bucket rather than the number of items per-page. This gives more sane initial sizes. - Only grow the bucket size when we face contention on the zone lock, this causes bucket sizes to grow more slowly. - Adjust the number of items per-bucket to account for the header space. This packs the buckets more efficiently per-page while making them not quite powers of two. - Eliminate the per-zone free bucket list. Always return buckets back to the bucket zone. This ensures that as zones grow into larger bucket sizes they eventually discard the smaller sizes. It persists fewer buckets in the system. The locking is slightly trickier. - Only switch buckets in zalloc, not zfree, this eliminates pathological cases where we ping-pong between two buckets. - Ensure that the thread that fills a new bucket gets to allocate from it to give a better upper bound on allocation time.
There used to be a problem with per CPU caches accumulating large amounts of items without freeing back to the global (or socket) pool. Do these updates to UMA change this situation and/or do you have further improvements coming up? -- Andre _______________________________________________ svn-src-head@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
