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nvme-multipath: Add visibility for numa io-policy

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This patch helps add nvme native multipath visibility for numa io-policy.
It adds a new attribute file named "numa_nodes" under namespace gendisk
device path node which prints the list of numa nodes preferred by the
given namespace path. The numa nodes value is comma delimited list of
nodes or A-B range of nodes.

For instance, if we have a shared namespace accessible from two different
controllers/paths then accessing head node of the shared namespace would
show the following output:

$ ls -l /sys/block/nvme1n1/multipath/
nvme1c1n1 -> ../../../../../pci052e:78/052e:78:00.0/nvme/nvme1/nvme1c1n1
nvme1c3n1 -> ../../../../../pci058e:78/058e:78:00.0/nvme/nvme3/nvme1c3n1

In the above example, nvme1n1 is head gendisk node created for a shared
namespace and this namespace is accessible from nvme1c1n1 and nvme1c3n1
paths. For numa io-policy we can then refer the "numa_nodes" attribute
file created under each namespace path:

$ cat /sys/block/nvme1n1/multipath/nvme1c1n1/numa_nodes
0-1

$ cat /sys/block/nvme1n1/multipath/nvme1c3n1/numa_nodes
2-3

>From the above output, we infer that I/O workload targeted at nvme1n1
and running on numa nodes 0 and 1 would prefer using path nvme1c1n1.
Similarly, I/O workload running on numa nodes 2 and 3 would prefer
using path nvme1c3n1. Reading "numa_nodes" file when configured
io-policy is anything but numa would show no output.

Reviewed-by: Sagi Grimberg <sagi@grimberg.me>
Reviewed-by: Hannes Reinecke <hare@suse.de>
Signed-off-by: Nilay Shroff <nilay@linux.ibm.com>
Signed-off-by: Keith Busch <kbusch@kernel.org>
This commit is contained in:
Nilay Shroff
2025-01-12 18:11:45 +05:30
committed by Keith Busch
parent 4dbd2b2ebe
commit 6546cc4a56
3 changed files with 33 additions and 0 deletions
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5
drivers/nvme/host/sysfs.c
View File

@@ -258,6 +258,7 @@ static struct attribute *nvme_ns_attrs[] = {
#ifdef CONFIG_NVME_MULTIPATH
&dev_attr_ana_grpid.attr,
&dev_attr_ana_state.attr,
&dev_attr_numa_nodes.attr,
#endif
&dev_attr_io_passthru_err_log_enabled.attr,
NULL,
@@ -290,6 +291,10 @@ static umode_t nvme_ns_attrs_are_visible(struct kobject *kobj,
if (!nvme_ctrl_use_ana(nvme_get_ns_from_dev(dev)->ctrl))
return 0;
}
if (a == &dev_attr_numa_nodes.attr) {
if (nvme_disk_is_ns_head(dev_to_disk(dev)))
return 0;
}
#endif
return a->mode;
}