> On Dec 16, 2020, at 9:00 AM, Yonghong Song <y...@fb.com> wrote:
>
>
>
> On 12/15/20 3:36 PM, Song Liu wrote:
>> This set introduces bpf_iter for task_vma, which can be used to generate
>> information similar to /proc/pid/maps or /proc/pid/smaps. Patch 4/4 adds
>
> I did not see an example for /proc/pid/smaps. It would be good if you can
> cover smaps as well since it is used by a lot of people.
smaps is tricky, as it contains a lot of information, and some of these
information
require architecture and configuration specific logic, e.g., page table
structure.
To really mimic smaps, we will probably need a helper for smap_gather_stats().
However, I don't think that's really necessary. I think task_vma iterator is
most
useful in gathering information that are not presented in smaps. For example,
if a
vma covers mixed 2MB pages and 4kB pages, smaps won't show which address ranges
are
backed by 2MB pages.
I have a test BPF program that parses 4-level x86 page table for huge pages.
Since
we need bounded-loop to parse the page table, the program won't work well for
too
big vma. We can probably add this program to samples/bpf/, but I think it is not
a good fit for selftests.
Thanks,
Song
