From: David Rientjes <rientjes@xxxxxxxxxx> Subject: mm, page_alloc: extend kernelcore and movablecore for percent Both kernelcore= and movablecore= can be used to define the amount of ZONE_NORMAL and ZONE_MOVABLE on a system, respectively. This requires the system memory capacity to be known when specifying the command line, however. This introduces the ability to define both kernelcore= and movablecore= as a percentage of total system memory. This is convenient for systems software that wants to define the amount of ZONE_MOVABLE, for example, as a proportion of a system's memory rather than a hardcoded byte value. To define the percentage, the final character of the parameter should be a '%'. mhocko: "why is anyone using these options nowadays?" rientjes: : Fragmentation of non-__GFP_MOVABLE pages due to low on memory : situations can pollute most pageblocks on the system, as much as 1GB of : slab being fragmented over 128GB of memory, for example. When the : amount of kernel memory is well bounded for certain systems, it is : better to aggressively reclaim from existing MIGRATE_UNMOVABLE : pageblocks rather than eagerly fallback to others. : : We have additional patches that help with this fragmentation if you're : interested, specifically kcompactd compaction of MIGRATE_UNMOVABLE : pageblocks triggered by fallback of non-__GFP_MOVABLE allocations and : draining of pcp lists back to the zone free area to prevent stranding. [rientjes@xxxxxxxxxx: updates] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802131700160.71590@xxxxxxxxxxxxxxxxxxxxxxxxx Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802121622470.179479@xxxxxxxxxxxxxxxxxxxxxxxxx Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx> Reviewed-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> Reviewed-by: Mike Kravetz <mike.kravetz@xxxxxxxxxx> Cc: Jonathan Corbet <corbet@xxxxxxx> Cc: Vlastimil Babka <vbabka@xxxxxxx> Cc: Mel Gorman <mgorman@xxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- Documentation/admin-guide/kernel-parameters.txt | 54 +++++++------- mm/page_alloc.c | 43 +++++++++-- 2 files changed, 62 insertions(+), 35 deletions(-) diff -puN Documentation/admin-guide/kernel-parameters.txt~mm-page_alloc-extend-kernelcore-and-movablecore-for-percent Documentation/admin-guide/kernel-parameters.txt --- a/Documentation/admin-guide/kernel-parameters.txt~mm-page_alloc-extend-kernelcore-and-movablecore-for-percent +++ a/Documentation/admin-guide/kernel-parameters.txt @@ -1840,30 +1840,29 @@ keepinitrd [HW,ARM] kernelcore= [KNL,X86,IA-64,PPC] - Format: nn[KMGTPE] | "mirror" - This parameter - specifies the amount of memory usable by the kernel - for non-movable allocations. The requested amount is - spread evenly throughout all nodes in the system. The - remaining memory in each node is used for Movable - pages. In the event, a node is too small to have both - kernelcore and Movable pages, kernelcore pages will - take priority and other nodes will have a larger number - of Movable pages. The Movable zone is used for the - allocation of pages that may be reclaimed or moved - by the page migration subsystem. This means that - HugeTLB pages may not be allocated from this zone. - Note that allocations like PTEs-from-HighMem still - use the HighMem zone if it exists, and the Normal + Format: nn[KMGTPE] | nn% | "mirror" + This parameter specifies the amount of memory usable by + the kernel for non-movable allocations. The requested + amount is spread evenly throughout all nodes in the + system as ZONE_NORMAL. The remaining memory is used for + movable memory in its own zone, ZONE_MOVABLE. In the + event, a node is too small to have both ZONE_NORMAL and + ZONE_MOVABLE, kernelcore memory will take priority and + other nodes will have a larger ZONE_MOVABLE. + + ZONE_MOVABLE is used for the allocation of pages that + may be reclaimed or moved by the page migration + subsystem. Note that allocations like PTEs-from-HighMem + still use the HighMem zone if it exists, and the Normal zone if it does not. - Instead of specifying the amount of memory (nn[KMGTPE]), - you can specify "mirror" option. In case "mirror" + It is possible to specify the exact amount of memory in + the form of "nn[KMGTPE]", a percentage of total system + memory in the form of "nn%", or "mirror". If "mirror" option is specified, mirrored (reliable) memory is used for non-movable allocations and remaining memory is used - for Movable pages. nn[KMGTPE] and "mirror" are exclusive, - so you can NOT specify nn[KMGTPE] and "mirror" at the same - time. + for Movable pages. "nn[KMGTPE]", "nn%", and "mirror" + are exclusive, so you cannot specify multiple forms. kgdbdbgp= [KGDB,HW] kgdb over EHCI usb debug port. Format: <Controller#>[,poll interval] @@ -2377,13 +2376,14 @@ mousedev.yres= [MOUSE] Vertical screen resolution, used for devices reporting absolute coordinates, such as tablets - movablecore=nn[KMG] [KNL,X86,IA-64,PPC] This parameter - is similar to kernelcore except it specifies the - amount of memory used for migratable allocations. - If both kernelcore and movablecore is specified, - then kernelcore will be at *least* the specified - value but may be more. If movablecore on its own - is specified, the administrator must be careful + movablecore= [KNL,X86,IA-64,PPC] + Format: nn[KMGTPE] | nn% + This parameter is the complement to kernelcore=, it + specifies the amount of memory used for migratable + allocations. If both kernelcore and movablecore is + specified, then kernelcore will be at *least* the + specified value but may be more. If movablecore on its + own is specified, the administrator must be careful that the amount of memory usable for all allocations is not too small. diff -puN mm/page_alloc.c~mm-page_alloc-extend-kernelcore-and-movablecore-for-percent mm/page_alloc.c --- a/mm/page_alloc.c~mm-page_alloc-extend-kernelcore-and-movablecore-for-percent +++ a/mm/page_alloc.c @@ -273,7 +273,9 @@ static unsigned long __meminitdata dma_r static unsigned long __meminitdata arch_zone_lowest_possible_pfn[MAX_NR_ZONES]; static unsigned long __meminitdata arch_zone_highest_possible_pfn[MAX_NR_ZONES]; static unsigned long __initdata required_kernelcore; +static unsigned long required_kernelcore_percent __initdata; static unsigned long __initdata required_movablecore; +static unsigned long required_movablecore_percent __initdata; static unsigned long __meminitdata zone_movable_pfn[MAX_NUMNODES]; static bool mirrored_kernelcore; @@ -6571,7 +6573,18 @@ static void __init find_zone_movable_pfn } /* - * If movablecore=nn[KMG] was specified, calculate what size of + * If kernelcore=nn% or movablecore=nn% was specified, calculate the + * amount of necessary memory. + */ + if (required_kernelcore_percent) + required_kernelcore = (totalpages * 100 * required_kernelcore_percent) / + 10000UL; + if (required_movablecore_percent) + required_movablecore = (totalpages * 100 * required_movablecore_percent) / + 10000UL; + + /* + * If movablecore= was specified, calculate what size of * kernelcore that corresponds so that memory usable for * any allocation type is evenly spread. If both kernelcore * and movablecore are specified, then the value of kernelcore @@ -6811,18 +6824,30 @@ void __init free_area_init_nodes(unsigne zero_resv_unavail(); } -static int __init cmdline_parse_core(char *p, unsigned long *core) +static int __init cmdline_parse_core(char *p, unsigned long *core, + unsigned long *percent) { unsigned long long coremem; + char *endptr; + if (!p) return -EINVAL; - coremem = memparse(p, &p); - *core = coremem >> PAGE_SHIFT; + /* Value may be a percentage of total memory, otherwise bytes */ + coremem = simple_strtoull(p, &endptr, 0); + if (*endptr == '%') { + /* Paranoid check for percent values greater than 100 */ + WARN_ON(coremem > 100); - /* Paranoid check that UL is enough for the coremem value */ - WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX); + *percent = coremem; + } else { + coremem = memparse(p, &p); + /* Paranoid check that UL is enough for the coremem value */ + WARN_ON((coremem >> PAGE_SHIFT) > ULONG_MAX); + *core = coremem >> PAGE_SHIFT; + *percent = 0UL; + } return 0; } @@ -6838,7 +6863,8 @@ static int __init cmdline_parse_kernelco return 0; } - return cmdline_parse_core(p, &required_kernelcore); + return cmdline_parse_core(p, &required_kernelcore, + &required_kernelcore_percent); } /* @@ -6847,7 +6873,8 @@ static int __init cmdline_parse_kernelco */ static int __init cmdline_parse_movablecore(char *p) { - return cmdline_parse_core(p, &required_movablecore); + return cmdline_parse_core(p, &required_movablecore, + &required_movablecore_percent); } early_param("kernelcore", cmdline_parse_kernelcore); _ -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
