On Wed, Sep 12, 2018 at 10:43 PM prakash.sangappa <prakash.sangappa@xxxxxxxxxx> wrote: > On 05/09/2018 04:31 PM, Dave Hansen wrote: > > On 05/07/2018 06:16 PM, prakash.sangappa wrote: > >> It will be /proc/<pid>/numa_vamaps. Yes, the behavior will be > >> different with respect to seeking. Output will still be text and > >> the format will be same. > >> > >> I want to get feedback on this approach. > > I think it would be really great if you can write down a list of the > > things you actually want to accomplish. Dare I say: you need a > > requirements list. > > > > The numa_vamaps approach continues down the path of an ever-growing list > > of highly-specialized /proc/<pid> files. I don't think that is > > sustainable, even if it has been our trajectory for many years. > > > > Pagemap wasn't exactly a shining example of us getting new ABIs right, > > but it sounds like something along those is what we need. > > Just sent out a V2 patch. This patch simplifies the file content. It > only provides VA range to numa node id information. > > The requirement is basically observability for performance analysis. > > - Need to be able to determine VA range to numa node id information. > Which also gives an idea of which range has memory allocated. > > - The proc file /proc/<pid>/numa_vamaps is in text so it is easy to > directly view. > > The V2 patch supports seeking to a particular process VA from where > the application could read the VA to numa node id information. > > Also added the 'PTRACE_MODE_READ_REALCREDS' check when opening the > file /proc file as was indicated by Michal Hacko procfs files should use PTRACE_MODE_*_FSCREDS, not PTRACE_MODE_*_REALCREDS.
