On 29 Aug 2011, at 17:33, Harald Barth wrote: > > PS: Some years ago I did some benchmarking of AFS cache performance. I > was astonished how much slower ext2 on ramdisk was compared to > memcache. So the question is, how fast could a AFS disk cache be if it > did not needed to bother with a file system and could use swap?
We've made significant improvements here with 1.6.0 - the performance of the AFS cache is now similar to the performance of the file system which underlies the cache. It's still slower than memcache (which has significantly less overhead), but does have the advantage that you don't have to permanently devote a chunk of your operating system's memory to the disk cache. Creating a block-device based cache is often discussed. The idea here is that you interface with the underlying storage at a block-based, rather than file-based level. You'd split your device into chunk sized records, and simply ship (portions of) those records to and from disk as required. Memory caching would be performed by the operating system caching AFS pages, so this would also avoid the double caching problem. It's a very interesting research project for anyone that has the time to actually implement it. Cheers, Simon. _______________________________________________ OpenAFS-info mailing list OpenAFS-info@openafs.org https://lists.openafs.org/mailman/listinfo/openafs-info
