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. Cheers, Dave. -- Dave Chinner david@xxxxxxxxxxxxx _______________________________________________ xfs mailing list xfs@xxxxxxxxxxx http://oss.sgi.com/mailman/listinfo/xfs
