Re: [PATCH v3 3/3] debugobjects: Reduce contention on pool lock in fill_pool()

[Leizhen (ThunderTown)]

On 2024/9/11 16:35, Zhen Lei wrote:
> If the conditions for starting fill are met, it means that all cores that
> call fill() later are blocked until the first core completes the fill
> operation.
> 
> Since it is low cost to move a set of free nodes from list obj_to_free
> into obj_pool, once it is necessary to fill, trying to move regardless
> of whether the context is preemptible. To reduce contention on pool
> lock, use atomic operation to test state. Only the first comer is allowed
> to try. If the last comer finds that someone is already trying, it will
> give up.
> 
> Scenarios that use allocated node filling can also be applied lockless
> mechanisms, but slightly different. The global list obj_to_free can only
> be operated exclusively by one core, while kmem_cache_zalloc() can be
> invoked by multiple cores simultaneously. Use atomic counting to mark how
> many cores are filling, to reduce atomic write conflicts during check. In
> principle, only the first comer is allowed to fill, but there is a very
> low probability that multiple comers may fill at the time.
> 
> Suggested-by: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
> Signed-off-by: Zhen Lei <thunder.leizhen@xxxxxxxxxx>

Hi, Thomas:
  I was going to mark "Signed-off-by" as you. Because except for the
following line of changes, you wrote everything. But you're maintainer.
It doesn't seem good if I post a patch with your Signed-off-by. Please
feel free to change it, but do not forget to add "Reported-by" or
"Tested-by" for me.

@@ -174,14 +198,14 @@ static void fill_pool(void)
 				last = new;
 		}
 		if (!cnt)
-			return;
+			break;

-- 
Regards,
  Zhen Lei