Re: [Xen-ia64-devel] kernel build performance data with dom0_VP modeopen

[Isaku Yamahata <yamahata@xxxxxxxxxxxxx>]

On Wed, May 24, 2006 at 10:23:10AM -0700, Magenheimer, Dan (HP Labs Fort 
Collins) wrote:
> At first, I suspected that this degradation was entirely
> due to the fact that large (64MB?) kernel pages were
> now causing many more TLB/VHPT misses because they are
> fragmented into 16KB pages.  However, I am
> seeing that domU performance is also reduced by ~3%,
> and domU had this fragmentation prior to VP.

Current the dom0vp model implementation flushes all tlb/vhpt
when granted page is unmapped from dom0.
I think this affects significantly on domU performance.


> Jingke, have you performed the same measurement on domU?
> If so, can you post your results?
> 
> Anybody have any other ideas as to what might be
> causing this (major) performance degradation?

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)


Thanks.

> 
> Thanks,
> Dan
> 
> ________________________________
> 
>       From: xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx
> [mailto:xen-ia64-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of Zhang,
> Jingke
>       Sent: Monday, May 22, 2006 1:49 AM
>       To: xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
>       Subject: [Xen-ia64-devel] kernel build performance data with
> dom0_VP modeopen
>       
>       
> 
>       Hi all,
> 
>                I have done kernel build with dom0_vp mode open to
> compare with it close. The specific data as following:
> 
>       Environment :
> 
>       Memory:768M
> 
>       Platform : tiger4
> 
>       Cpu : Montecito C1 stepping
> 
>       Compile cmdline : time make >/dev/null 2>&1
> 
>       Configuration file : @arch/ia64/config/tiger_defconfig
> 
>        
> 
>                                                      time
> Real                    user                    sys   
> 
>       Cset 10027 (with dom0_vp open):             14m48.377s
> 13m43.960s     0m51.670s
> 
>       Cset 10022 (with dom0_vp closed):          14m5.752s
> 13m13.200s     0m39.260s
> 
>       Native :
> 13m55.572s    13m4.366s       0m35.205s
> 
>       Performance : 
> 
>       Cset 10022: dom0/native =98.7%
> 
>       Cset 10027:dom0/native=94.1%
> 
>        
> 
>       From the result, we can see when dom0_vp mode open, the
> performance of KB has 4.6% degradation. 
> 
>       Thanks 
> 
>       Zhang Jingke
> 
> 
> _______________________________________________
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> Xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
> http://lists.xensource.com/xen-ia64-devel
> 

-- 
yamahata

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