Re: [PATCH/RFC] Shared page tables

Brian Twichell
2006-01-31T18:48:04Z

Ray Bryant wrote:

>On Friday 27 January 2006 16:50, Brian Twichell wrote:
><snip>
>
>
>
>>Hi,
>>
>>We collected more granular performance data for the ppc64/hugepage case.
>>
>>CPI decreased by 3% when shared pagetables were used. Underlying this was
>>a 7% decrease in the overall TLB miss rate. The TLB miss rate for
>>hugepages decreased 39%. TLB miss rates are calculated per instruction
>>executed.
>>
>>
>>
>
>Interesting.
>
>Do you know if Dave's patch supports sharing of pte's for 2 MB pages on
>X86_64?
>
>
I believe it does. Dave, can you confirm ?

>Was there a corresponding improvement in overall transaction throughput for
>the hugetlb, shared pte case? That is, did the 3% improvement in CPI
>translate to a measurable improvement in the overall OLTP benchmark score?
>
>
Yes. My original post with performance data described a 3% improvement
in the ppc64/hugepage case. This is a transaction throughput statement.

>(I'm assuming your 25-50% improvement measurements, as mentioned in a previous
>note, was for small pages.)
>
>
>
That's correct.