RE: [Xen-ia64-devel] [PATCH] [RESEND] domU destroy & page ref counter

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

>From: Dong, Eddie
>Sent: 2006年3月13日 22:12
>A minor suggestion for next in my mind is that we may add a simple COMPILE 
>option
>in Makefile or some .h file to be able to choice 1/3 byte swap or 1/2 byte 
>swap.
>People has some thoughts that 1/2 byte swap may have better hash locality.
>
>Eddie.
I second Eddie,

I have some observations about this.
Usually guest applications use almost the address space, the only different is 
rid. What I observed was if the lowest 17 bits of rid are same, the hash 
address 
is same. If we swap 1/3 byte, applications use the same address space but 
different 
rid may have the hash address in a majority of situations, which may make some 
collision chains very long.

These are just some observations, I don't mean 1/2 byte swap is better than 1/3 
byte swap.I think we need to add COMPILE option to get benchmark data first, 
and 
then make the decision.

It's obviously not a big task but deserve to do. One thing we need to pay extra
attention is the rid byte swap is done in assembly code in some 
fast_hyperpriops.

Thanks,
Anthony

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