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SubjectRe: RFC: Memory Tiering Kernel Interfaces (v2)
On Wed, May 25, 2022 at 4:37 AM Mika Penttilä <mpenttil@redhat.com> wrote:
>
>
>
> On 25.5.2022 13.01, Aneesh Kumar K V wrote:
> > On 5/25/22 2:33 PM, Ying Huang wrote:
> >> On Tue, 2022-05-24 at 22:32 -0700, Wei Xu wrote:
> >>> On Tue, May 24, 2022 at 1:24 AM Ying Huang <ying.huang@intel.com> wrote:
> >>>>
> >>>> On Tue, 2022-05-24 at 00:04 -0700, Wei Xu wrote:
> >>>>> On Thu, May 19, 2022 at 8:06 PM Ying Huang <ying.huang@intel.com>
> >>>>> wrote:
> >>>>>>
> >
> > ...
> >
> >>
> >> OK. Just to confirm. Does this mean that we will have fixed device ID,
> >> for example,
> >>
> >> GPU memtier255
> >> DRAM (with CPU) memtier0
> >> PMEM memtier1
> >>
> >> When we add a new memtier, it can be memtier254, or memter2? The rank
> >> value will determine the real demotion order.
> >>
> >> I think you may need to send v3 to make sure everyone is at the same
> >> page.
> >>
> >
> > What we have implemented which we will send as RFC shortly is below.
> >
> > cd /sys/dekvaneesh@ubuntu-guest:~$ cd /sys/devices/system/
> > kvaneesh@ubuntu-guest:/sys/devices/system$ pwd
> > /sys/devices/system
> > kvaneesh@ubuntu-guest:/sys/devices/system$ ls
> > clockevents clocksource container cpu edac memory memtier mpic
> > node power
> > kvaneesh@ubuntu-guest:/sys/devices/system$ cd memtier/
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier$ pwd
> > /sys/devices/system/memtier
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier$ ls
> > default_rank max_rank memtier1 power uevent
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier$ cat default_rank
> > 1
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier$ cat max_rank
> > 3
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier$ cd memtier1/
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier/memtier1$ ls
> > nodelist power rank subsystem uevent
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier/memtier1$ cat nodelist
> > 0-3
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier/memtier1$ cat rank
> > 1
> > kvaneesh@ubuntu-guest:/sys/devices/system/memtier/memtier1$ cd
> > ../../node/node1/
> > kvaneesh@ubuntu-guest:/sys/devices/system/node/node1$ cat memtier
> > 1
> > kvaneesh@ubuntu-guest:/sys/devices/system/node/node1$
> > root@ubuntu-guest:/sys/devices/system/node/node1# echo 0 > memtier
> > root@ubuntu-guest:/sys/devices/system/node/node1# cat memtier
> > 0
> > root@ubuntu-guest:/sys/devices/system/node/node1# cd ../../memtier/
> > root@ubuntu-guest:/sys/devices/system/memtier# ls
> > default_rank max_rank memtier0 memtier1 power uevent
> > root@ubuntu-guest:/sys/devices/system/memtier# cd memtier0/
> > root@ubuntu-guest:/sys/devices/system/memtier/memtier0# cat nodelist
> > 1
> > root@ubuntu-guest:/sys/devices/system/memtier/memtier0# cat rank
> > 0
> > root@ubuntu-guest:/sys/devices/system/memtier/memtier0# echo 4 > rank
> > bash: rank: Permission denied
> > root@ubuntu-guest:/sys/devices/system/memtier/memtier0#
> >
>
> Just to confirm, unlike today's demotion code, the demotion target
> allocation is planned to honor mempolicies?

Yes, though there will be some limitations in the beginning,
specifically for per-thread mempolicy.

>
> --Mika
>
>

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