Re: [Xen-ia64-devel] kernel build performance data with dom0_VPmodeopen

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

64MB was wrong. 16MB VHPT for P=M.

On Fri, May 26, 2006 at 09:31:16AM +0800, Xu, Anthony wrote:
> I'm surprised too,
> It is 256x smaller VHPT size.
> We need to get performance data with P=M and VHPT=64k.
> 
> Thanks,
> -Anthony 
> 
> >-----Original Message-----
> >From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
> >[mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Magenheimer,
> >Dan (HP Labs Fort Collins)
> >Sent: 2006?5?26? 1:29
> >To: Isaku Yamahata
> >Cc: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> >Subject: RE: [Xen-ia64-devel] kernel build performance data with
> >dom0_VPmodeopen
> >
> >> For dom0vp model, VHPT size is reduced to 64KBytes to avoid
> >> triggering software lock detection.
> >> For P=M model, its size remain 64MB.
> >> It would be interesting to measure on P=M model with 64KBtyes
> >> VHPT size.
> >> (Edit VHPT_SIZE_LOG2 in xen/include/asm-ia64/vhpt.h)
> >
> >Yes, having a VHPT that is 1024x smaller is likely
> >to make a big difference in performance.  I'm surprised
> >it isn't worse!
> >
> >I agree it would be interesting to measure P==M with
> >the smaller vhpt (Jingke, is this a measurement you
> >could easily make on your system?), but since we are
> >definitely moving ahead with VP it would be good to
> >look forward rather than back.
> >
> >Can you explain in more detail about the software lock
> >detection and why a 64KB VHPT avoids it?  Any ideas on
> >how to get to a larger VHPT (not necessarily as large
> >as 64MB)?
> >
> >Thanks,
> >Dan
> >
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> 
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> 

-- 
yamahata

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