From a5c6d6509342785bef53bf9508e1842b303f1878 Mon Sep 17 00:00:00 2001 From: David Rientjes Date: Thu, 5 Apr 2018 16:23:09 -0700 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@google.com: updates] Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802131700160.71590@chino.kir.corp.google.com Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1802121622470.179479@chino.kir.corp.google.com Signed-off-by: David Rientjes Reviewed-by: Andrew Morton Reviewed-by: Mike Kravetz Cc: Jonathan Corbet Cc: Vlastimil Babka Cc: Mel Gorman Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/page_alloc.c | 43 +++++++++++++++++++++++++++++++++++-------- 1 file changed, 35 insertions(+), 8 deletions(-) (limited to 'mm/page_alloc.c') diff --git a/mm/page_alloc.c b/mm/page_alloc.c index a3e2ba4f76bb..766ffb5fa94b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -273,7 +273,9 @@ static unsigned long __meminitdata dma_reserve; 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_pfns_for_nodes(void) } /* - * 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(unsigned long *max_zone_pfn) 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_kernelcore(char *p) 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_kernelcore(char *p) */ 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); -- cgit