Re: [PATCH v3] mm/lruvec: trace LRU add drains and drain-all requests

[Vlastimil Babka (SUSE)]

On 6/18/26 10:21, David Hildenbrand (Arm) wrote:
> On 6/17/26 20:18, Vlastimil Babka (SUSE) wrote:
>> On 6/17/26 17:03, Shakeel Butt wrote:
>>> On Wed, Jun 17, 2026 at 01:11:16PM +0200, David Hildenbrand (Arm) wrote:
>>>>
>>>> Given that trace events can quickly become stable ABI [1], are we really sure we
>>>> want to add this?
>>>
>>> Yes, I think so as this is useful to get insights into lru cache draining.
>>> Trace events being stable or not is secondary IMHO. If in future we rearchitect
>>> the lru page handling where there is no cache draining anymore, we can make
>>> these a noops.
>> 
>> Yeah and I don't recall ever that a change to a mm tracepoint would ever
>> break someone who'd complain and we'd have to revert it.
> Really? :)
> 
> Read the context of the link I posted once more.

Ah, I see. I've only read the single mail from Steven that referred to the
old powertop breakage and didn't notice the context.

But I don't think these worries should stop us from adding easily usable
tracepoints.