Messages in this thread Patch in this message | | | From | Mina Almasry <> | Date | Mon, 14 Nov 2022 11:14:26 -0800 | Subject | Re: [PATCH v1] virtio_pmem: populate numa information |
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On Sun, Nov 13, 2022 at 9:44 AM Pankaj Gupta <pankaj.gupta.linux@gmail.com> wrote: > > > > Pankaj Gupta wrote: > > > > > > > Compute the numa information for a virtio_pmem device from the memory > > > > > > > range of the device. Previously, the target_node was always 0 since > > > > > > > the ndr_desc.target_node field was never explicitly set. The code for > > > > > > > computing the numa node is taken from cxl_pmem_region_probe in > > > > > > > drivers/cxl/pmem.c. > > > > > > > > > > > > > > Signed-off-by: Michael Sammler <sammler@google.com> > > > > Tested-by: Mina Almasry <almasrymina@google.com> > > > > I don't have much expertise on this driver, but with the help of this > > patch I was able to get memory tiering [1] emulation going on qemu. As > > far as I know there is no alternative to this emulation, and so I > > would love to see this or equivalent merged, if possible. > > > > This is what I have going to get memory tiering emulation: > > > > In qemu, added these configs: > > -object memory-backend-file,id=m4,share=on,mem-path="$path_to_virtio_pmem_file",size=2G > > \ > > -smp 2,sockets=2,maxcpus=2 \ > > -numa node,nodeid=0,memdev=m0 \ > > -numa node,nodeid=1,memdev=m1 \ > > -numa node,nodeid=2,memdev=m2,initiator=0 \ > > -numa node,nodeid=3,initiator=0 \ > > -device virtio-pmem-pci,memdev=m4,id=nvdimm1 \ > > > > On boot, ran these commands: > > ndctl_static create-namespace -e namespace0.0 -m devdax -f 1&> /dev/null > > echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind > > echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id > > for i in `ls /sys/devices/system/memory/`; do > > state=$(cat "/sys/devices/system/memory/$i/state" 2&>/dev/null) > > if [ "$state" == "offline" ]; then > > echo online_movable > "/sys/devices/system/memory/$i/state" > > fi > > done > > Nice to see the way to handle the virtio-pmem device memory through kmem driver > and online the corresponding memory blocks to 'zone_movable'. > > This also opens way to use this memory range directly irrespective of attached > block device. Of course there won't be any persistent data guarantee. But good > way to simulate memory tiering inside guest as demonstrated below. > > > > Without this CL, I see the memory onlined in node 0 always, and is not > > a separate memory tier. With this CL and qemu configs, the memory is > > onlined in node 3 and is set as a separate memory tier, which enables > > qemu-based development: > > > > ==> /sys/devices/virtual/memory_tiering/memory_tier22/nodelist <== > > 3 > > ==> /sys/devices/virtual/memory_tiering/memory_tier4/nodelist <== > > 0-2 > > > > AFAIK there is no alternative to enabling memory tiering emulation in > > qemu, and would love to see this or equivalent merged, if possible. > > Just wondering if Qemu vNVDIMM device can also achieve this? >
I spent a few minutes on this. Please note I'm really not familiar with these drivers, but as far as I can tell the qemu vNVDIMM device has the same problem and needs a similar fix to this to what Michael did here. What I did with vNVDIMM qemu device:
- Added these qemu configs: -object memory-backend-file,id=m4,share=on,mem-path=./hello,size=2G,readonly=off \ -device nvdimm,id=nvdimm1,memdev=m4,unarmed=off \
- Ran the same commands in my previous email (they seem to apply to the vNVDIMM device without modification): ndctl_static create-namespace -e namespace0.0 -m devdax -f 1&> /dev/null echo dax0.0 > /sys/bus/dax/drivers/device_dax/unbind echo dax0.0 > /sys/bus/dax/drivers/kmem/new_id for i in `ls /sys/devices/system/memory/`; do state=$(cat "/sys/devices/system/memory/$i/state" 2&>/dev/null) if [ "$state" == "offline" ]; then echo online_movable > "/sys/devices/system/memory/$i/state" fi done
I see the memory from the vNVDIMM device get onlined on node0, and is not detected as a separate memory tier. I suspect that driver needs a similar fix to this one.
> In any case, this patch is useful, So, > Reviewed-by: Pankaj Gupta <pankaj.gupta@amd.com > > > > > > > > > [1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/ABI/testing/sysfs-kernel-mm-memory-tiers > > > > > > > > > --- > > > > > > > drivers/nvdimm/virtio_pmem.c | 11 +++++++++-- > > > > > > > 1 file changed, 9 insertions(+), 2 deletions(-) > > > > > > > > > > > > > > diff --git a/drivers/nvdimm/virtio_pmem.c b/drivers/nvdimm/virtio_pmem.c > > > > > > > index 20da455d2ef6..a92eb172f0e7 100644 > > > > > > > --- a/drivers/nvdimm/virtio_pmem.c > > > > > > > +++ b/drivers/nvdimm/virtio_pmem.c > > > > > > > @@ -32,7 +32,6 @@ static int init_vq(struct virtio_pmem *vpmem) > > > > > > > static int virtio_pmem_probe(struct virtio_device *vdev) > > > > > > > { > > > > > > > struct nd_region_desc ndr_desc = {}; > > > > > > > - int nid = dev_to_node(&vdev->dev); > > > > > > > struct nd_region *nd_region; > > > > > > > struct virtio_pmem *vpmem; > > > > > > > struct resource res; > > > > > > > @@ -79,7 +78,15 @@ static int virtio_pmem_probe(struct virtio_device *vdev) > > > > > > > dev_set_drvdata(&vdev->dev, vpmem->nvdimm_bus); > > > > > > > > > > > > > > ndr_desc.res = &res; > > > > > > > - ndr_desc.numa_node = nid; > > > > > > > + > > > > > > > + ndr_desc.numa_node = memory_add_physaddr_to_nid(res.start); > > > > > > > + ndr_desc.target_node = phys_to_target_node(res.start); > > > > > > > + if (ndr_desc.target_node == NUMA_NO_NODE) { > > > > > > > + ndr_desc.target_node = ndr_desc.numa_node; > > > > > > > + dev_dbg(&vdev->dev, "changing target node from %d to %d", > > > > > > > + NUMA_NO_NODE, ndr_desc.target_node); > > > > > > > + } > > > > > > > > > > > > As this memory later gets hotplugged using "devm_memremap_pages". I don't > > > > > > see if 'target_node' is used for fsdax case? > > > > > > > > > > > > It seems to me "target_node" is used mainly for volatile range above > > > > > > persistent memory ( e.g kmem driver?). > > > > > > > > > > > I am not sure if 'target_node' is used in the fsdax case, but it is > > > > > indeed used by the devdax/kmem driver when hotplugging the memory (see > > > > > 'dev_dax_kmem_probe' and '__dax_pmem_probe'). > > > > > > > > Yes, but not currently for FS_DAX iiuc. > > > > > > The target_node is only used by the dax_kmem driver. In the FSDAX case > > > the memory (persistent or otherwise) is mapped behind a block-device. > > > That block-device has affinity to a CPU initiator, but that memory does > > > not itself have any NUMA affinity or identity as a target. > > > > > > So: > > > > > > block-device NUMA node == closest CPU initiator node to the device > > > > > > dax-device target node == memory only NUMA node target, after onlining
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