On 09/08/13 20:33, Dave Chinner wrote:
From: Dave Chinner<dchinner@xxxxxxxxxx> CPU overhead of buffer lookups dominate most metadata intensive workloads. The thing is, most such workloads are hitting a relatively small number of buffers repeatedly, and so caching recently hit buffers is a good idea. Add a hashed lookaside buffer that records the recent buffer lookup successes and is searched first before doing a rb-tree lookup. If we get a hit, we avoid the expensive rbtree lookup and greatly reduce the overhead of the lookup. If we get a cache miss, then we've added an extra CPU cacheline miss into the lookup.
Interesting. The last allocated xfs_buf is placed into the hash. Might be interesting to know the hit-miss ratio on a real workload. --Mark. _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
