On 6/16/22 9:15 AM, Wei Xu wrote: > On Wed, Jun 15, 2022 at 6:11 PM Ying Huang <ying.huang@xxxxxxxxx> wrote: >> >> On Tue, 2022-06-14 at 14:56 -0400, Johannes Weiner wrote: >>> On Tue, Jun 14, 2022 at 01:31:37PM +0530, Aneesh Kumar K V wrote: .... >> As Jonathan Cameron pointed, we may need the memory tier ID to be >> stable if possible. I know this isn't a easy task. At least we can >> make the default memory tier (CPU local DRAM) ID stable (for example >> make it always 128)? That provides an anchor for users to understand. > > One of the motivations of introducing "rank" is to allow memory tier > ID to be stable, at least for the well-defined tiers such as the > default memory tier. The default memory tier can be moved around in > the tier hierarchy by adjusting its rank position relative to other > tiers, but its device ID can remain the same, e.g. always 1. > With /sys/devices/system/memtier/default_tier userspace will be able query the default tier details. Did you get to look at https://lore.kernel.org/linux-mm/7b72ccf4-f4ae-cb4e-f411-74d055482026@xxxxxxxxxxxxx Any reason why that will not work with all the requirements we had? -aneesh
