Re: [RFC 1/4] sched: Add CPU rate soft caps

Re: [RFC 1/4] sched: Add CPU rate soft caps

[Con Kolivas]

On Sunday 04 June 2006 11:08, Peter Williams wrote:
> 3. Thanks to suggestions from Con Kolivas with respect to alternative
> methods to reduce the possibility of a task being starved of CPU while
> holding an important system resource, enforcement of caps is now
> quite strict.  However, there will still be occasions where caps may be
> exceeded due to this mechanism vetoing enforcement.

Transcription bug here:

>  int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
>  {
> +	int ret;
> +
>  	might_sleep();
>  	return __mutex_fastpath_lock_retval
>  			(&lock->count, __mutex_lock_interruptible_slowpath);

should be ret = 

> +
> +	if (!ret)
> +		inc_mutex_count();
> +
> +	return ret;
>  }
>

compare with here:

>  EXPORT_SYMBOL(mutex_lock_interruptible);
> @@ -366,8 +390,13 @@ static inline int __mutex_trylock_slowpa
>   */
>  int fastcall __sched mutex_trylock(struct mutex *lock)
>  {
> -	return __mutex_fastpath_trylock(&lock->count,
> +	int ret = __mutex_fastpath_trylock(&lock->count,
>  					__mutex_trylock_slowpath);
> +
> +	if (!ret)
> +		inc_mutex_count();
> +
> +	return ret;
>  }
>
>  EXPORT_SYMBOL(mutex_trylock);

-- 
-ck

Re: [RFC 1/4] sched: Add CPU rate soft caps

[Peter Williams]

Con Kolivas wrote:
> On Sunday 04 June 2006 11:08, Peter Williams wrote:
>> 3. Thanks to suggestions from Con Kolivas with respect to alternative
>> methods to reduce the possibility of a task being starved of CPU while
>> holding an important system resource, enforcement of caps is now
>> quite strict.  However, there will still be occasions where caps may be
>> exceeded due to this mechanism vetoing enforcement.
> 
> Transcription bug here:
> 
>>  int fastcall __sched mutex_lock_interruptible(struct mutex *lock)
>>  {
>> +	int ret;
>> +
>>  	might_sleep();
>>  	return __mutex_fastpath_lock_retval
>>  			(&lock->count, __mutex_lock_interruptible_slowpath);
> 
> should be ret = 

How embarrassing.  I wonder why I didn't notice an "unreachable code" 
warning here?

Thanks
Peter
-- 
Peter Williams                                   pwil3058@bigpond.net.au

"Learning, n. The kind of ignorance distinguishing the studious."
  -- Ambrose Bierce