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The current implementation treats emulated memory devices, such as CXL1.1 type3 memory, as normal DRAM when they are emulated as normal memory (E820_TYPE_RAM). However, these emulated devices have different characteristics than traditional DRAM, making it important to distinguish them. Thus, we modify the tiered memory initialization process to introduce a delay specifically for CPUless NUMA nodes. This delay ensures that the memory tier initialization for these nodes is deferred until HMAT information is obtained during the boot process. Finally, demotion tables are recalculated at the end. * late_initcall(memory_tier_late_init); Some device drivers may have initialized memory tiers between `memory_tier_init()` and `memory_tier_late_init()`, potentially bringing online memory nodes and configuring memory tiers. They should be excluded in the late init. * Handle cases where there is no HMAT when creating memory tiers There is a scenario where a CPUless node does not provide HMAT information. If no HMAT is specified, it falls back to using the default DRAM tier. * Introduce another new lock `default_dram_perf_lock` for adist calculation In the current implementation, iterating through CPUlist nodes requires holding the `memory_tier_lock`. However, `mt_calc_adistance()` will end up trying to acquire the same lock, leading to a potential deadlock. Therefore, we propose introducing a standalone `default_dram_perf_lock` to protect `default_dram_perf_*`. This approach not only avoids deadlock but also prevents holding a large lock simultaneously. * Upgrade `set_node_memory_tier` to support additional cases, including default DRAM, late CPUless, and hot-plugged initializations. To cover hot-plugged memory nodes, `mt_calc_adistance()` and `mt_find_alloc_memory_type()` are moved into `set_node_memory_tier()` to handle cases where memtype is not initialized and where HMAT information is available. * Introduce `default_memory_types` for those memory types that are not initialized by device drivers. Because late initialized memory and default DRAM memory need to be managed, a default memory type is created for storing all memory types that are not initialized by device drivers and as a fallback. Link: https://lkml.kernel.org/r/20240405000707.2670063-3-horenchuang@bytedance.com Signed-off-by: Ho-Ren (Jack) Chuang <horenchuang@bytedance.com> Signed-off-by: Hao Xiang <hao.xiang@bytedance.com> Reviewed-by: "Huang, Ying" <ying.huang@intel.com> Reviewed-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: Aneesh Kumar K.V <aneesh.kumar@linux.ibm.com> Cc: Dan Williams <dan.j.williams@intel.com> Cc: Dave Jiang <dave.jiang@intel.com> Cc: Gregory Price <gourry.memverge@gmail.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Ravi Jonnalagadda <ravis.opensrc@micron.com> Cc: SeongJae Park <sj@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Vishal Verma <vishal.l.verma@intel.com> Cc: Jonathan Cameron <Jonathan.Cameron@huawie.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
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| kernel | ||
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| COPYING | ||
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| README | ||
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.