MaliPerfDoc: Why do I get a perf. warning telling me to recycle descriptor sets when Vulkan already has a descriptor sets pool?

In my application I need sometimes to allocate a new descriptor set and retire the old one to be deleted after all the frames that are using it are finished.

Because Vulkan has a descriptor set pool, I assumed that recycling descriptor sets was the intended use case for this.

Why am I getting the following performance warning? Is it serious enough to have to add our own pool, on the top of the Vulkan pool?

PERFORMANCE WARNING: [MaliPerfDoc] Code 17 : It appears that some redundant descriptor set allocations happened. Consider recycling descriptor sets.

Thanks,

Lorenzo