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Date: Mon, 12 Feb 2018 16:24:25 -0800 (PST)
From: David Rientjes <rientjes@...gle.com>
To: Andrew Morton <akpm@...ux-foundation.org>
cc: Jonathan Corbet <corbet@....net>, Vlastimil Babka <vbabka@...e.cz>,
Mel Gorman <mgorman@...e.de>, linux-kernel@...r.kernel.org,
linux-mm@...ck.org, linux-doc@...r.kernel.org
Subject: [patch 1/2] 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 '%'.
Signed-off-by: David Rientjes <rientjes@...gle.com>
---
Documentation/admin-guide/kernel-parameters.txt | 44 ++++++++++++-------------
mm/page_alloc.c | 43 +++++++++++++++++++-----
2 files changed, 57 insertions(+), 30 deletions(-)
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -1825,30 +1825,30 @@
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
- zone if it does not.
-
- Instead of specifying the amount of memory (nn[KMGTPE]),
- you can specify "mirror" option. In case "mirror"
+ 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. 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 zone if it does not.
+
+ 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]
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -272,7 +272,9 @@ 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;
@@ -6477,7 +6479,18 @@ 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
@@ -6717,18 +6730,30 @@ 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;
}
@@ -6744,7 +6769,8 @@ 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);
}
/*
@@ -6753,7 +6779,8 @@ 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);
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