On 2012-11-23 18:44, Tang Chen wrote: > [What we are doing] > This patchset provide a boot option for user to specify ZONE_MOVABLE memory > map for each node in the system. > > movablecore_map=nn[KMG]@ss[KMG] > Hi Tang, DMA address can't be set as movable, if some one boot kernel with movablecore_map=4G@0xa00000 or other memory region that contains DMA address, system maybe boot failed. Should this case be handled or mentioned in the change log and kernel-parameters.txt? Thanks, Jianguo Wu > This option make sure memory range from ss to ss+nn is movable memory. > > > [Why we do this] > If we hot remove a memroy, the memory 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. > > 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. > > 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. > > So we proposed a new feature which specifies memory range to use as > movable memory. > > > [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 chose second way, because if we use first way, users cannot change > memory range to use as movable memory easily. We think if we create > movable memory, performance regression may occur by NUMA. In this case, > user can turn off the feature easily if we prepare the boot option. > And if we prepare the boot optino, the user can select which memory > to use as movable memory easily. > > > [How to use] > Specify the following boot option: > movablecore_map=nn[KMG]@ss[KMG] > > That means physical address range from ss to ss+nn will be allocated as > ZONE_MOVABLE. > > And the following points should be considered. > > 1) If the range is involved in a single node, then from ss to the end of > the node will be ZONE_MOVABLE. > 2) If the range covers two or more nodes, then from ss to the end of > the node will be ZONE_MOVABLE, and all the other nodes will only > have ZONE_MOVABLE. > 3) If no range is in the node, then the node will have no ZONE_MOVABLE > unless kernelcore or movablecore is specified. > 4) This option could be specified at most MAX_NUMNODES times. > 5) If kernelcore or movablecore is also specified, movablecore_map will have > higher priority to be satisfied. > 6) This option has no conflict with memmap option. > > > > Tang Chen (4): > page_alloc: add movable_memmap kernel parameter > page_alloc: Introduce zone_movable_limit[] to keep movable limit for > nodes > page_alloc: Make movablecore_map has higher priority > page_alloc: Bootmem limit with movablecore_map > > Yasuaki Ishimatsu (1): > x86: get pg_data_t's memory from other node > > Documentation/kernel-parameters.txt | 17 +++ > arch/x86/mm/numa.c | 11 ++- > include/linux/memblock.h | 1 + > include/linux/mm.h | 11 ++ > mm/memblock.c | 15 +++- > mm/page_alloc.c | 216 ++++++++++++++++++++++++++++++++++- > 6 files changed, 263 insertions(+), 8 deletions(-) > > -- > To unsubscribe, send a message with 'unsubscribe linux-mm' in > the body to majordomo@xxxxxxxxx. For more info on Linux MM, > see: http://www.linux-mm.org/ . > Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a> > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>