On 12/12/2013 03:56 PM, Dave Chinner wrote: > On Thu, Dec 12, 2013 at 01:59:26PM -0500, Brian Foster wrote: >> On 12/12/2013 02:22 AM, Dave Chinner wrote: >>> From: Dave Chinner <dchinner@xxxxxxxxxx> >>> >>> The hashkey calculation is very simplistic,and throws away an amount >>> of entropy that should be folded into the hash. The result is >>> sub-optimal distribution across the hash tables. For example, with a >>> default 512 entry table, phase 2 results in this: >>> >> ... >>> Modify the hash to be something more workable - steal the linux >>> kernel inode hash calculation and try that: >>> >> ... >>> >>> Kinda says it all, really... >>> >>> Signed-off-by: Dave Chinner <dchinner@xxxxxxxxxx> >>> --- >> >> Results look nice and the algorithm seems to match the kernel variant, >> but what about the 32-bit alternate prime/cache line values? Safe to >> leave out..? > > The buffer cache uses a 64 bit key, regardless of the platform. > Therefore the 64 bit variant is always needed. The kernel inode hash > uses a 32 bit key on 32 bit systems, which is why there are two > variants for it. > Ah.. xfs_bufkey->blkno is an xfs_daddr_t, which is an __int64_t. Thanks. Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx> > Cheers, > > Dave. > _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
