Re: [RFC][PATCH] O(1) Entitlement Based Scheduler

[Peter Williams <peterw@aurema.com>]

Andi Kleen wrote:
> On Wed, Mar 03, 2004 at 02:45:28PM +1100, Peter Williams wrote:
> 
>>Andi Kleen wrote:
>>
>>>Peter Williams <peterw@aurema.com> writes:
>>>
>>>One comment on the patches: could you remove the zillions of numerical 
>>>Kconfig
>>>options and just make them sysctls? I don't think it makes any sense 
>>>to require a reboot to change any of that. And the user is unlikely
>>>to have much idea yet on what he wants on them while configuring.
>>
>>The default initial values should be fine and the default configuration 
>>allows the scheduling tuning parameters (i.e. half life and time slice 
>>      ) to be changed on a running system via the /proc file system. 
>>These are mainly there so that different settings can be used with 
>>various benchmarks to determine what are the best settings for various 
>>types of loads.  If good default values that work well for a wide 
>>variety of load types can be found as a result of these experiments then 
>>these parameters may be made constants in the code.  If not they 
>>probably should be made settable via system calls rather than via /proc 
>>as you suggest.
> 
> 
> No doubt that there are different settings that make sense 
> for different workloads. But there is no reason one has to recompile
> to set them - it's much nicer to just run a script at boot time to set
> them, instead of recompiling/rebooting. This will also make benchmarking
> much easier, because you can just write a script that sets the
> various parameters, runs workloads, sets other parameters, runs
> workload again etc. Requiring a recompile and reboot makes this
> much harder.

As I said (with the full patch) these values can be set via /proc on a 
running system so there's no need for a recompile and reboot.

> 
> Also I suspect most people who are not heavily into scheduling
> theory will go with the defaults at compile time, so it's important
> that they already work well.
> 
> And consider it from the side of a standard distribution: users 
> don't normally recompile their kernels there, so everything that
> makes sense to be tunable should be settable without recompiling.
> 
> IMHO CONFIG_* should not be used for anything except for kernel binary
> size tuning and possible compiler tuning.

Yes, once this patch has stabilised we will probably remove some (or 
all) of the configuration variables.

Peter
-- 
Dr Peter Williams, Chief Scientist                peterw@aurema.com
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