port make index (was: Re: make -j$n buildworld : use of -j investigated)

[Ronald Klop]

On Thu, 25 Nov 2004 16:19:02 +0900, Rob <spamrefuse at yahoo.com> wrote:

> Rob wrote:
>> Brian Szymanski wrote:
>>
>>> Did you try any machines that used Hyperthreading? I'd be interested to
>>> see how those machines fare based on the number of logical and real  
>>> CPUs.
>>>
>>>
>>>> Although people suggest "-j4" as optimal in general
>>>> case, I have come to a very different conclusion:
>>>>
>>>> 1) single CPU with enough RAM (2 GHz, 512 MB)
>>>>    there's no significant speed up in the range
>>>>    "-j1" to "-j9".
>>>>    So "-j1" is as good as "-j9".
>>>
>>>
>>>
>>> If you went to all that trouble, you might as well post the numbers :-)
>>   Time unit is minutes.
>>  CPU: 2x800 MHz    2000 MHz    333 MHz
>> RAM:  1024 MB      512 MB      64 MB
>> -j   --------------------------------
>> 1        99          50        276
>> 2        58          49        291
>> 3        58          50        367
>> 4        57          50        547
>> 5        58          49
>> 6        58          50
>> 7        57          50
>> 8        58          50
>> 9        58          50
>
> I have run another test on a 700 MHz, 128 MB PC,
> and the following equation seems to hold for all
> my tests. Calculate:
>
>      time(minutes) * speed(MHz) * nproc / 1000 MHz
>
> and if this results in approximately 1, the system
> is optimized.
>
> For example, in the above case,
>
> column 1:
> -j1 :  99 * 800 * 2 / 1000 = 1.5
> -j2 :  58 * 800 * 2 / 1000 = 0.928
>
> column 2:
> -j1 : 50 * 2000 * 1 / 1000 = 1
>
> column 3:
> -j1 : 276 * 333 * 1 / 1000 = 0.919
>
> another PC:
> -j1 : 142 * 700 * 1 / 1000 = 0.994
>
> --------------
>
> All PCs have "standard" hardware. Off-the-shelf
> mainboard, IDE harddisks, nothing special really.
>
> All this is done on 5.3-Stable systems and the time
> listed (in minutes) is for the buildworld only:
> "make -jn buildworld"
>
> Rob.

Would all this work for 'make index' for the ports also? Or is this more  
io bound?
I can't test this myself, because my laptop is to slow for making these  
tests any fun.

Ronald.

-- 
  Ronald Klop, Amsterdam, The Netherlands