Re: [generalized cache events] Re: [PATCH 1/1] perf tools: Add missing user space support for config1/config2

[Ingo Molnar <mingo@elte.hu>]

* Ingo Molnar <mingo@elte.hu> wrote:

> * arun@sharma-home.net <arun@sharma-home.net> wrote:
> 
> > On Fri, Apr 22, 2011 at 12:52:11PM +0200, Ingo Molnar wrote:
> > > 
> > > Using the generalized cache events i can run:
> > > 
> > >  $ perf stat --repeat 10 -e cycles:u -e instructions:u -e l1-dcache-loads:u -e l1-dcache-load-misses:u ./array
> > > 
> > >  Performance counter stats for './array' (10 runs):
> > > 
> > >          6,719,130 cycles:u                   ( +-   0.662% )
> > >          5,084,792 instructions:u           #      0.757 IPC     ( +-   0.000% )
> > >          1,037,032 l1-dcache-loads:u          ( +-   0.009% )
> > >          1,003,604 l1-dcache-load-misses:u    ( +-   0.003% )
> > > 
> > >         0.003802098  seconds time elapsed   ( +-  13.395% )
> > > 
> > > I consider that this is 'bad', because for almost every dcache-load there's a 
> > > dcache-miss - a 99% L1 cache miss rate!
> > 
> > One could argue that all you need is cycles and instructions. [...]
> 
> Yes, and note that with instructions events we even have skid-less PEBS 
> profiling so seeing the precise .
                                  - location of instructions is possible.

[ An email gremlin ate that part of the sentence. ]

Thanks,

	Ingo