Messages in this thread | | | Date | Fri, 28 Feb 2003 11:40:56 +0100 | From | Andi Kleen <> | Subject | Re: [Lse-tech] Re: [PATCH] New dcache / inode hash tuning patch |
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On Fri, Feb 28, 2003 at 02:27:27AM -0800, Paul Menage wrote: > >But for lookup walking even one cache line - the one containing d_hash - > >should be needed. Unless d_hash is unlucky enough to cross a cache > >line for its two members ... but I doubt that. > > No, but on a 32-byte cache line system, d_parent, d_hash and d_name are > all on different cache lines, and they're used when checking each entry.
... and dcache RCU checks d_bucket and d_move_count too in the hash walking loop.
> On 64-byte systems, d_parent and d_hash will be on the same line, but > d_name is still on a separate line and d_name.hash gets checked before > d_parent. So bringing these three fields on to the same cacheline > would theoretically be a win.
Ok you're right. Optimizing the layout a bit would be probably a good idea. I won't include it in the hash patchkit for now to not do too many things with the same patch.
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