Re: [Valgrind-users] why miss rate decrease but number of misses increase in ubuntu 12 in vmware player 12 ?

[Josef W. <Jos...@gm...>]

Am 15.02.2016 um 11:25 schrieb Mandy Martino:
> why 
> 
> I1 misses increase, LLi misses increase, LL misses increase, D1 misses
> increase
> though miss rate decrease at this row 0.1%     +       0.0% ?
> 
> which indicator show the correct number that can show the improvement
> after optimization?

I see you do blocking in the 2nd version. However, the number of data
accesses is 166 million vs. 10 million in your 1st version. I assume
this is because you did not compile with -O2 or -O3 ?

Miss rate is a relative number, based on total number of accesses.
A comparison is meaningless if the number of accesses is so different.

Josef


> 
> 
> #define min(a,b) (((a)<(b))?(a):(b))
> #define max(a,b) (((a)>(b))?(a):(b))
> int main()
> {
>  int x[100][100];
>  int y[100][100];
>  int z[100][100];
>  int i=0;
>  int j=0;
>  int k=0;
>  int N=100;
>  int r=0;
>  int jj=0;
>  int kk=0;
>  int B = 5;
> /*
>  for(i=0;i<N;++i)
>  {
>   for(j=0;j<N;++j)
>   {
>    r=0;
>    for(k=0;k<N;++k)
>    {
>      r=r+y[i][k]*z[k][j];
>    }
>    x[i][j]=r;
>   }
>  }
> */
>  for(jj=0;jj<N;jj=jj+B)
>  for(kk=0;kk<N;kk=kk+B)
>  for(i=0;i<N;++i)
>  {
>   for(j=0;j<min(jj+B,N);++j)
>   {
>    r=0;
>    for(k=kk;k<min(kk+B,N);++k)
>    {
>      r=r+y[i][k]*z[k][j];
>    }
>    x[i][j]=x[i][j]+r;
>   }
>  }
>  return 0;
> }
> /*
>  for(i=0;i<N;++i)
>  {
>   for(j=0;j<N;++j)
>   {
>    r=0;
>    for(k=0;k<N;++k)
>    {
>      r=r+y[i][k]*z[k][j];
>    }
>    x[i][j]=r;
>   }
>  }
> 
> martin@ubuntu:~$ valgrind --tool=cachegrind ./mar5ti
> ==4602== Cachegrind, a cache and branch-prediction profiler
> ==4602== Copyright (C) 2002-2011, and GNU GPL'd, by Nicholas Nethercote
> et al.
> ==4602== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
> ==4602== Command: ./mar5ti
> ==4602== 
> --4602-- warning: L3 cache found, using its data for the LL simulation.
> ==4602== 
> ==4602== I   refs:      14,264,184
> ==4602== I1  misses:           689
> ==4602== LLi misses:           684
> ==4602== I1  miss rate:       0.00%
> ==4602== LLi miss rate:       0.00%
> ==4602== 
> ==4602== D   refs:      10,163,336  (10,117,945 rd   + 45,391 wr)
> ==4602== D1  misses:        64,978  (    64,200 rd   +    778 wr)
> ==4602== LLd misses:         2,823  (     2,063 rd   +    760 wr)
> ==4602== D1  miss rate:        0.6% (       0.6%     +    1.7%  )
> ==4602== LLd miss rate:        0.0% (       0.0%     +    1.6%  )
> ==4602== 
> ==4602== LL refs:           65,667  (    64,889 rd   +    778 wr)
> ==4602== LL misses:          3,507  (     2,747 rd   +    760 wr)
> ==4602== LL miss rate:         0.0% (       0.0%     +    1.6%  )
> 
>  for(jj=0;jj<N;jj=jj+B)
>  for(kk=0;kk<N;kk=kk+B)
>  for(i=0;i<N;++i)
>  {
>   for(j=0;j<min(jj+B,N);++j)
>   {
>    r=0;
>    for(k=kk;k<min(kk+B,N);++k)
>    {
>      r=r+y[i][k]*z[k][j];
>    }
>    x[i][j]=x[i][j]+r;
>   }
>  }
> martin@ubuntu:~$ valgrind --tool=cachegrind ./mar5ti
> ==4654== Cachegrind, a cache and branch-prediction profiler
> ==4654== Copyright (C) 2002-2011, and GNU GPL'd, by Nicholas Nethercote
> et al.
> ==4654== Using Valgrind-3.7.0 and LibVEX; rerun with -h for copyright info
> ==4654== Command: ./mar5ti
> ==4654== 
> --4654-- warning: L3 cache found, using its data for the LL simulation.
> ==4654== 
> ==4654== I   refs:      265,277,487
> ==4654== I1  misses:            690
> ==4654== LLi misses:            685
> ==4654== I1  miss rate:        0.00%
> ==4654== LLi miss rate:        0.00%
> ==4654== 
> ==4654== D   refs:      166,275,677  (159,919,965 rd   + 6,355,712 wr)
> ==4654== D1  misses:        170,231  (    170,082 rd   +       149 wr)
> ==4654== LLd misses:          2,823  (      2,688 rd   +       135 wr)
> ==4654== D1  miss rate:         0.1% (        0.1%     +       0.0%  )
> ==4654== LLd miss rate:         0.0% (        0.0%     +       0.0%  )
> ==4654== 
> ==4654== LL refs:           170,921  (    170,772 rd   +       149 wr)
> ==4654== LL misses:           3,508  (      3,373 rd   +       135 wr)
> ==4654== LL miss rate:          0.0% (        0.0%     +       0.0%  )
> 
> */
> 
> 
> Regards,
> 
> 
> Martin
> 
> 
> 
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