Before this patch-set, we introduced movablemem_map boot option which allowed users to specify physical address ranges to set memory as movable. This is not user friendly enough for normal users. So now, we introduce just movablemem_map=acpi to allow users to enable/disable the kernel to use Hot Pluggable bit in SRAT to determine which memory ranges are hotpluggable, and set them as ZONE_MOVABLE. This patch-set is based on Yinghai's patch-set: v1: https://lkml.org/lkml/2013/3/7/642 v2: https://lkml.org/lkml/2013/3/10/47 So it supports to allocate pagetable pages in local nodes. We also split the large patch-set into smaller ones, and it seems easier to review. ======================================================================== [What we are doing] This patchset introduces a boot option for users to specify ZONE_MOVABLE memory map for each node in the system. Users can use it in two ways: 1. movablecore_map=acpi In this way, the kernel will use Hot Pluggable bit in SRAT to determine ZONE_MOVABLE for each node. All the ranges user has specified will be ignored. [Why we do this] If we hot remove a memroy device, it cannot have kernel memory, because Linux cannot migrate kernel memory currently. Therefore, we have to guarantee that the hot removed memory has only movable memoroy. (Here is an exception: When we implement the node hotplug functionality, for those kernel memory whose life cycle is the same as the node, such as pagetables, vmemmap and so on, although the kernel cannot migrate them, we can still put them on local node because we can free them before we hot-remove the node. This is not completely implemented yet.) Linux has two boot options, kernelcore= and movablecore=, for creating movable memory. These boot options can specify the amount of memory use as kernel or movable memory. Using them, we can create ZONE_MOVABLE which has only movable memory. (NOTE: doing this will cause NUMA performance because the kernel won't be able to distribute kernel memory evenly to each node.) But it does not fulfill a requirement of memory hot remove, because even if we specify the boot options, movable memory is distributed in each node evenly. So when we want to hot remove memory which memory range is 0x80000000-0c0000000, we have no way to specify the memory as movable memory. Furthermore, even if we can use SRAT, users still need an interface to enable/disable this functionality if they don't want to lose their NUMA performance. So I think, a user interface is always needed. So we proposed this new feature which enable/disable the kernel to set hotpluggable memory as ZONE_MOVABLE. [Ways to do this] There may be 2 ways to specify movable memory. 1. use firmware information 2. use boot option 1. use firmware information According to ACPI spec 5.0, SRAT table has memory affinity structure and the structure has Hot Pluggable Filed. See "5.2.16.2 Memory Affinity Structure". If we use the information, we might be able to specify movable memory by firmware. For example, if Hot Pluggable Filed is enabled, Linux sets the memory as movable memory. 2. use boot option This is our proposal. New boot option can specify memory range to use as movable memory. [How we do this] We now propose a boot option, but support the first way above. A boot option is always needed because set memory as movable will cause NUMA performance down. So at least, we need an interface to enable/disable it so that users who don't want to use memory hotplug functionality will also be happy. [How to use] Specify movablemem_map=acpi in kernel commandline: * * SRAT: |_____| |_____| |_________| |_________| ...... * node id: 0 1 1 2 * hotpluggable: n y y n * ZONE_MOVABLE: |_____| |_________| * NOTE: 1) Before parsing SRAT, memblock has already reserve some memory ranges for other purposes, such as for kernel image. We cannot prevent kernel from using these memory, so we need to exclude these memory even if it is hotpluggable. Furthermore, to ensure the kernel has enough memory to boot, we make all the memory on the node which the kernel resides in should be un-hotpluggable. 2) In this case, all the user specified memory ranges will be ingored. We also need to consider the following points: 1) Using this boot option could cause NUMA performance down because the kernel memory will not be distributed on each node evenly. So for users who don't want to lose their NUMA performance, just don't use it. 2) If kernelcore or movablecore is also specified, movablecore_map will have higher priority to be satisfied. 3) This option has no conflict with memmap option. Tane Chen (10): acpi: Print hotplug info in SRAT. numa, acpi, memory-hotplug: Add movablemem_map=acpi boot option. x86, numa, acpi, memory-hotplug: Introduce hotplug info into struct numa_meminfo. x86, numa, acpi, memory-hotplug: Consider hotplug info when cleanup numa_meminfo. X86, numa, acpi, memory-hotplug: Add hotpluggable ranges to movablemem_map. x86, numa, acpi, memory-hotplug: Make any node which the kernel resides in un-hotpluggable. x86, numa, acpi, memory-hotplug: Introduce zone_movable_limit[] to store start pfn of ZONE_MOVABLE. x86, numa, acpi, memory-hotplug: Sanitize zone_movable_limit[]. x86, numa, acpi, memory-hotplug: make movablemem_map have higher priority x86, numa, acpi, memory-hotplug: Memblock limit with movablemem_map Yasuaki Ishimatsu (1): x86: get pg_data_t's memory from other node Documentation/kernel-parameters.txt | 11 ++ arch/x86/include/asm/numa.h | 3 +- arch/x86/kernel/apic/numaq_32.c | 2 +- arch/x86/mm/amdtopology.c | 3 +- arch/x86/mm/numa.c | 92 ++++++++++++++-- arch/x86/mm/numa_internal.h | 1 + arch/x86/mm/srat.c | 28 ++++- include/linux/memblock.h | 2 + include/linux/mm.h | 19 +++ mm/memblock.c | 50 ++++++++ mm/page_alloc.c | 210 ++++++++++++++++++++++++++++++++++- 11 files changed, 399 insertions(+), 22 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-doc" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
