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In a typical memory tiering system, there's no CPU in slow (PMEM) NUMA nodes. But if the number of the hint page faults on a PMEM node is the max for a task, The current NUMA balancing policy may try to place the task on the PMEM node instead of DRAM node. This is unreasonable, because there's no CPU in PMEM NUMA nodes. To fix this, CPU-less nodes are ignored when searching the migration target node for a task in this patch. To test the patch, we run a workload that accesses more memory in PMEM node than memory in DRAM node. Without the patch, the PMEM node will be chosen as preferred node in task_numa_placement(). While the DRAM node will be chosen instead with the patch. Signed-off-by: "Huang, Ying" <ying.huang@intel.com> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Link: https://lkml.kernel.org/r/20220214121553.582248-2-ying.huang@intel.com
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 Restructured Text 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.