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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>
Linux kernel
============
There are several guides for kernel developers and users. These guides can
be rendered in a number of formats, like HTML and PDF. Please read
Documentation/admin-guide/README.rst first.
In order to build the documentation, use ``make htmldocs`` or
``make pdfdocs``. The formatted documentation can also be read online at:
https://www.kernel.org/doc/html/latest/
There are various text files in the Documentation/ subdirectory,
several of them using the reStructuredText markup notation.
Please read the Documentation/process/changes.rst file, as it contains the
requirements for building and running the kernel, and information about
the problems which may result by upgrading your kernel.