Messages in this thread | | | Date | Wed, 1 Jun 2022 19:19:58 +0530 | Subject | Re: [RFC PATCH v4 4/7] mm/demotion/dax/kmem: Set node's memory tier to MEMORY_TIER_PMEM | From | Aneesh Kumar K V <> |
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On 6/1/22 11:59 AM, Bharata B Rao wrote: > On 5/27/2022 5:55 PM, Aneesh Kumar K.V wrote: >> From: Jagdish Gediya <jvgediya@linux.ibm.com> >> >> By default, all nodes are assigned to DEFAULT_MEMORY_TIER which >> is memory tier 1 which is designated for nodes with DRAM, so it >> is not the right tier for dax devices. >> >> Set dax kmem device node's tier to MEMORY_TIER_PMEM, In future, >> support should be added to distinguish the dax-devices which should >> not be MEMORY_TIER_PMEM and right memory tier should be set for them. >> >> Signed-off-by: Jagdish Gediya <jvgediya@linux.ibm.com> >> Signed-off-by: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> >> --- >> drivers/dax/kmem.c | 4 ++++ >> mm/migrate.c | 2 ++ >> 2 files changed, 6 insertions(+) >> >> diff --git a/drivers/dax/kmem.c b/drivers/dax/kmem.c >> index a37622060fff..991782aa2448 100644 >> --- a/drivers/dax/kmem.c >> +++ b/drivers/dax/kmem.c >> @@ -11,6 +11,7 @@ >> #include <linux/fs.h> >> #include <linux/mm.h> >> #include <linux/mman.h> >> +#include <linux/migrate.h> >> #include "dax-private.h" >> #include "bus.h" >> >> @@ -147,6 +148,9 @@ static int dev_dax_kmem_probe(struct dev_dax *dev_dax) >> >> dev_set_drvdata(dev, data); >> >> +#ifdef CONFIG_TIERED_MEMORY >> + node_set_memory_tier(numa_node, MEMORY_TIER_PMEM); >> +#endif > > I was experimenting with this patchset and found this behaviour. > Here's what I did: > > Boot a KVM guest with vNVDIMM device which ends up with device_dax > driver by default. > > Use it as RAM by binding it to dax kmem driver. It now appears as > RAM with a new NUMA node that is put to memtier1 (the existing tier > where DRAM already exists) >
That should have placed it in memtier2.
> I can move it to memtier2 (MEMORY_RANK_PMEM) manually, but isn't > that expected to happen automatically when a node with dax kmem > device comes up? >
This can happen if we have added the same NUMA node to memtier1 before dax kmem driver initialized the pmem memory. Can you check before the above node_set_memory_tier_rank() whether the specific NUMA node is already part of any memory tier?
Thank you for testing the patchset. -aneesh
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