Re: [PATCH v10 3/6] fs/proc/task_mmu: Implement IOCTL to get and/or the clear info about PTEs

From: Nadav Amit
Date: Tue Feb 28 2023 - 21:00:00 EST




> On Feb 28, 2023, at 11:31 AM, Peter Xu <peterx@xxxxxxxxxx> wrote:
>
>> Anyhow, thanks for all the explanations. Eventually, I understand that
>> using bitmaps can be more efficient than a log if the bits are condensed.
>
> Note that I think what Muhammad (sorry, Muhammad! I think I spelled your
> name wrongly before starting from some email..) proposed is not a bitmap,
> but an array of ranges that can coalesce the result into very condensed
> form. Pros and cons.
>
> Again, I can't comment much on that API, but since there're a bunch of
> other developers looking at that and they're also potential future users,
> I'll trust their judgement and just focus more on the other side of things.


Thanks Peter for your patience.

I would just note that I understood that Muhammad did not propose a condensed
bitmap, and that was a hint that handling a condensed bitmap (at least on x86)
can be done rather efficiently. I am not sure about other representations.

Thanks for your explanations again, Peter.