Re: [RFC PATCH 00/30] Code tagging framework and applications

David Hildenbrand
2022-09-01T15:07:26Z

On 01.09.22 16:23, Kent Overstreet wrote:
> On Thu, Sep 01, 2022 at 10:05:03AM +0200, David Hildenbrand wrote:
>> On 31.08.22 21:01, Kent Overstreet wrote:
>>> On Wed, Aug 31, 2022 at 12:47:32PM +0200, Michal Hocko wrote:
>>>> On Wed 31-08-22 11:19:48, Mel Gorman wrote:
>>>>> Whatever asking for an explanation as to why equivalent functionality
>>>>> cannot not be created from ftrace/kprobe/eBPF/whatever is reasonable.
>>>>
>>>> Fully agreed and this is especially true for a change this size
>>>> 77 files changed, 3406 insertions(+), 703 deletions(-)
>>>
>>> In the case of memory allocation accounting, you flat cannot do this with ftrace
>>> - you could maybe do a janky version that isn't fully accurate, much slower,
>>> more complicated for the developer to understand and debug and more complicated
>>> for the end user.
>>>
>>> But please, I invite anyone who's actually been doing this with ftrace to
>>> demonstrate otherwise.
>>>
>>> Ftrace just isn't the right tool for the job here - we're talking about adding
>>> per callsite accounting to some of the fastest fast paths in the kernel.
>>>
>>> And the size of the changes for memory allocation accounting are much more
>>> reasonable:
>>> 33 files changed, 623 insertions(+), 99 deletions(-)
>>>
>>> The code tagging library should exist anyways, it's been open coded half a dozen
>>> times in the kernel already.
>>
>> Hi Kent,
>>
>> independent of the other discussions, if it's open coded already, does
>> it make sense to factor that already-open-coded part out independently
>> of the remainder of the full series here?
>
> It's discussed in the cover letter, that is exactly how the patch series is
> structured.

Skimming over the patches (that I was CCed on) and skimming over the
cover letter, I got the impression that everything after patch 7 is
introducing something new instead of refactoring something out.

>
>> [I didn't immediately spot if this series also attempts already to
>> replace that open-coded part]
>
> Uh huh.
>
> Honestly, some days it feels like lkml is just as bad as slashdot, with people
> wanting to get in their two cents without actually reading...

... and of course you had to reply like that. I should just have learned
from my last upstream experience with you and kept you on my spam list.

Thanks, bye

--
Thanks,

David / dhildenb