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

David Hildenbrand
2022-09-01T08:05:59Z

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?

[I didn't immediately spot if this series also attempts already to
replace that open-coded part]

--
Thanks,

David / dhildenb