Re: [RFC PATCH V4 1/1] mm: add last level page table numa info to /proc/pid/numa_pgtable

[haoxin]

在 2022/8/4 下午4:12, David Hildenbrand 写道:
> On 04.08.22 10:04, haoxin wrote:
> > 在 2022/8/1 下午9:28, David Hildenbrand 写道:
> > > On 01.08.22 14:17, Xin Hao wrote:
> > > > In many data center servers, the shared memory architectures is
> > > > Non-Uniform Memory Access (NUMA), remote numa node data access
> > > > often brings a high latency problem, but what we are easy to ignore
> > > > is that the page table remote numa access, It can also leads to a
> > > > performance degradation.
> > > Let me try rewriting:
> > >
> > > "
> > > Many data center servers employ Non-Uniform Memory Access (NUMA)
> > > architectures. Remote numa memory access results in high latency. While
> > > memory placement is one issue, sub-optimal page table placement can also
> > > result in surprise performance degradation.
> > > "
> > Thanks,  it reads more clearly.
> >
> > > > So there add a new interface in /proc, This will help developers to
> > > > get more info about performance issues if they are caused by cross-NUMA.
> > > Why do we only care about "last level page table", why not about the others?
> > >
> > > IMHO, we could emit something like "0, 1, 3, 0" instead for a given user
> > > space address, showing the NUMA node the page table belongs to from
> > > highest to lowest page table level.
> > I have planned to implement the PTE page table in this version first,
> > and then support other page tables in the next patch later.
> If there are plans, let's do it all at once, to get a good and single
> interface to expose that information.
Ok, thanks for your suggestion, I will implement it in the next version.

>