RE: [patch] sched: auto-tune migration costs [was: Re: Industry db benchmark result on recent 2.6 kernels]

["Chen, Kenneth W" <kenneth.w.chen@intel.com>]

Ingo Molnar wrote on Monday, April 04, 2005 8:05 PM
>
> latest patch attached. Changes:
>
>  - stabilized calibration even more, by using cache flushing
>    instructions to generate a predictable working set. The cache
>    flushing itself is not timed, it is used to create quiescent
>    cache  state.
>
>    I only guessed the ia64 version - e.g. i didnt know what 'type'
>    argument to pass to ia64_sal_cache_flush() to get a d/cache
>    flush+invalidate.

It is preferable to use a ia64_pal_cache_flush instead of SAL call. But
it hangs the machine with that pal call.  I will look at it tomorrow.
The type argument for sal_cache_flush is: 1 for icache, 2 for dcache,
and 3 for i+d.


>  - due to more stable results, reduced ITERATIONS from 3 to 2 - this
>    should further speed up calibration.
>
> tested on x86, the calibration results look ok there.

Calibration result on ia64 (1.5 GHz, 9 MB), somewhat smaller in this
version compare to earlier estimate of 10.4ms.  The optimal setting
found by a db workload is around 16 ms.

---------------------
| migration cost matrix (max_cache_size: 9437184, cpu: -1 MHz):

---------------------
          [00]    [01]    [02]    [03]
[00]:     -     9.3(0)  9.3(0)  9.3(0)
[01]:   9.3(0)    -     9.3(0)  9.3(0)
[02]:   9.3(0)  9.3(0)    -     9.3(0)
[03]:   9.3(0)  9.3(0)  9.3(0)    -
--------------------------------
| cacheflush times [1]: 9.3 (9329800)
| calibration delay: 16 seconds
--------------------------------