Re: [PATCH v1 01/31] x86/resctrl: Fix allocation of cleanest CLOSID on platforms with no monitors

David Hildenbrand
2024-04-09T15:06:09Z

On 09.04.24 17:02, Reinette Chatre wrote:
> Hi David,
>

Hi,

> (Thank you very much for taking a look at these)

I'm planning on reviewing more; as most of resctrl is code I haven't
really read before, I'm not able to make progress as fast as I normally
would in core-MM ... :)

>
> On 4/9/2024 1:05 AM, David Hildenbrand wrote:
>> On 21.03.24 17:50, James Morse wrote:
>>> commit 6eac36bb9eb0 ("x86/resctrl: Allocate the cleanest CLOSID by
>>> searching closid_num_dirty_rmid") added a Kconfig option that causes
>>> resctrl to search for the CLOSID with the fewest dirty cache lines when
>>> creating a new control group. This depends on the values read from the
>>> llc_occupancy counters.
>>>
>>> This support missed that some platforms may not have these counters.
>>> This causes a NULL pointer dereference when creating a new control
>>> group as the array was not allocated by dom_data_init().
>>>
>>> As this feature isn't necessary on platforms that don't have cache
>>> occupancy monitors, add this to the check that occurs when a new
>>> control group is allocated.
>>>
>>> The existing code is not selected by any upstream platform, it makes
>>> no sense to backport this patch to stable.
>>>
>>
>> It's weird to not see RESCTRL_RMID_DEPENDS_ON_CLOSID appear in any Kconfig file.
>> I guess it will all make sense once the refactoring is done :)
>
> This is done later in this series where patch #29, "fs/resctrl: Add boiler
> plate for external resctrl code", introduces it to fs/resctrl/Kconfig.

Oh, already in this series, great!

--
Cheers,

David / dhildenb