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

["Dong, Eddie" <eddie.dong@xxxxxxxxx>]

Yes, I remembered your suggestion. That is why I suggest to
enable a compile option so that somebody can start formal benchmark measurement 
:-)
Eddie

Magenheimer, Dan (HP Labs Fort Collins) wrote:
> Rid mangling change has been discussed many times on the list,
> most recently:
> 
> http://lists.xensource.com/archives/html/xen-ia64-devel/2005-11/msg00282.html
> 
>> -----Original Message-----
>> From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
>> [mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Xu,
>> Anthony Sent: Monday, March 13, 2006 6:37 PM
>> To: Dong, Eddie; Tian, Kevin; Akio Takebe; Masaki Kanno;
>> xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>> Subject: RE: [Xen-ia64-devel] [PATCH] [RESEND] domU destroy & page
>> ref counter 
>> 
>>> 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
>> 
>> _______________________________________________
>> Xen-ia64-devel mailing list
>> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-ia64-devel


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