[lkml]   [2018]   [Sep]   [14]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
Messages in this thread
SubjectRe: [PATCH V2 0/6] VA to numa node information
On Thu, 13 Sep 2018 15:32:25 -0700 "prakash.sangappa" <> wrote:

> >>
> > It would be really great to give a short summary of the previous
> > discussion. E.g. why do we need a proc interface in the first place when
> > we already have an API to query for the information you are proposing to
> > export [1]
> >
> > [1]
> The proc interface provides an efficient way to export address range
> to numa node id mapping information compared to using the API.
> For example, for sparsely populated mappings, if a VMA has large portions
> not have any physical pages mapped, the page walk done thru the /proc file
> interface can skip over non existent PMDs / ptes. Whereas using the
> API the application would have to scan the entire VMA in page size units.
> Also, VMAs having THP pages can have a mix of 4k pages and hugepages.
> The page walks would be efficient in scanning and determining if it is
> a THP huge page and step over it. Whereas using the API, the application
> would not know what page size mapping is used for a given VA and so would
> have to again scan the VMA in units of 4k page size.
> If this sounds reasonable, I can add it to the commit / patch description.

Preferably with some runtime measurements, please. How much faster is
this interface in real-world situations? And why does that performance

It would also be useful to see more details on how this info helps
operators understand/tune/etc their applications and workloads. In
other words, I'm trying to get an understanding of how useful this code
might be to our users in general.

 \ /
  Last update: 2018-09-14 02:11    [W:1.775 / U:0.244 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site