* [PATCH V2 1/4] munmap: mem unmap operation size handling
2011-06-27 13:41 [PATCH V2 0/4] munmap: Flexible mem unmap operation interface for scheduling latency Geunsik Lim
@ 2011-06-27 13:41 ` Geunsik Lim
2011-06-27 13:41 ` [PATCH V2 2/4] munmap: sysctl extension for tunable parameter Geunsik Lim
` (2 subsequent siblings)
3 siblings, 0 replies; 5+ messages in thread
From: Geunsik Lim @ 2011-06-27 13:41 UTC (permalink / raw)
To: Ingo Molnar, Andrew Morton, Peter Zijlstra, Hugh Dickins,
Steven Rostedt
Cc: Thomas Gleixner, H. Peter Anvin, Darren Hart, linux-kernel,
linux-mm
From: Geunsik Lim <geunsik.lim@samsung.com>
The specification of H/W(CPU, memory, I/O bandwidth, etc) is different
according to their SOC. We can earn a suitable performance(or latency)
after adjust memory unmap size by selecting an optimal value to consider
specified system environment in real world.
In other words, We can get real-fast or real-time using the Linux kernel
tunable parameter choosingly for flexible memory unmap operation unit.
Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>
Acked-by: Hyunjin Choi <hj89.choi@samsung.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Steven Rostedt <rostedt@redhat.com>
CC: Hugh Dickins <hughd@google.com>
CC: Randy Dunlap <randy.dunlap@oracle.com>
CC: Ingo Molnar <mingo@elte.hu>
---
include/linux/munmap_unit_size.h | 24 ++++++++++++++++
mm/Makefile | 4 ++-
mm/memory.c | 21 +++++++++++-----
mm/munmap_unit_size.c | 57 ++++++++++++++++++++++++++++++++++++++
4 files changed, 84 insertions(+), 1 deletions(-)
create mode 100644 include/linux/munmap_unit_size.h
create mode 100644 mm/munmap_unit_size.c
diff --git a/include/linux/munmap_unit_size.h b/include/linux/munmap_unit_size.h
new file mode 100644
index 0000000..c4f1fd4
--- /dev/null
+++ b/include/linux/munmap_unit_size.h
@@ -0,0 +1,24 @@
+/*
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * Due to this file being licensed under the GPL there is controversy over
+ * whether this permits you to write a module that #includes this file
+ * without placing your module under the GPL. Please consult a lawyer for
+ * advice before doing this.
+ *
+ */
+
+#ifdef CONFIG_MMU
+extern unsigned long munmap_unit_size;
+extern unsigned long sysctl_munmap_unit_size;
+#else
+#define sysctl_munmap_unit_size 0UL
+#endif
+
+#ifdef CONFIG_MMU
+extern int munmap_unit_size_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos);
+#endif
diff --git a/mm/Makefile b/mm/Makefile
index 42a8326..4b55b6c 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -5,7 +5,9 @@
mmu-y := nommu.o
mmu-$(CONFIG_MMU) := fremap.o highmem.o madvise.o memory.o mincore.o \
mlock.o mmap.o mprotect.o mremap.o msync.o rmap.o \
- vmalloc.o pagewalk.o pgtable-generic.o
+ vmalloc.o pagewalk.o pgtable-generic.o \
+ munmap_unit_size.o
+
obj-y := filemap.o mempool.o oom_kill.o fadvise.o \
maccess.o page_alloc.o page-writeback.o \
diff --git a/mm/memory.c b/mm/memory.c
index ce22a25..8573cb6 100644
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -57,6 +57,7 @@
#include <linux/swapops.h>
#include <linux/elf.h>
#include <linux/gfp.h>
+#include <linux/munmap_unit_size.h>
#include <asm/io.h>
#include <asm/pgalloc.h>
@@ -1088,12 +1089,10 @@ static unsigned long unmap_page_range(struct mmu_gather *tlb,
return addr;
}
-#ifdef CONFIG_PREEMPT
-# define ZAP_BLOCK_SIZE (8 * PAGE_SIZE)
-#else
-/* No preempt: go for improved straight-line efficiency */
-# define ZAP_BLOCK_SIZE (1024 * PAGE_SIZE)
-#endif
+/* No preempt: go for improved straight-line efficiency
+ * on PREEMPT(preemptive mode) this is not a critical latency-path.
+ */
+# define ZAP_BLOCK_SIZE (munmap_unit_size * PAGE_SIZE)
/**
* unmap_vmas - unmap a range of memory covered by a list of vma's
diff --git a/mm/munmap_unit_size.c b/mm/munmap_unit_size.c
new file mode 100644
index 0000000..1a2a2c6
--- /dev/null
+++ b/mm/munmap_unit_size.c
@@ -0,0 +1,57 @@
+/*
+ * Memory Unmap Operation Unit Interface
+ * (C) Geunsik Lim, April 2011
+ */
+
+#include <linux/init.h>
+#include <linux/mm.h>
+#include <linux/munmap_unit_size.h>
+#include <linux/sysctl.h>
+
+/* amount of vm to unmap from userspace access by both non-preemptive mode
+ * and preemptive mode
+ */
+unsigned long munmap_unit_size;
+
+/*
+ * Memory unmap operation unit of vm to release allocated memory size from
+ * userspace using mmap system call
+ */
+#if !defined(CONFIG_PREEMPT_VOLUNTARY) && !defined(CONFIG_PREEMPT)
+unsigned long sysctl_munmap_unit_size = CONFIG_PREEMPT_NO_MUNMAP_RANGE;
+#else
+unsigned long sysctl_munmap_unit_size = CONFIG_PREEMPT_OK_MUNMAP_RANGE;
+#endif
+
+/*
+ * Update munmap_unit_size that changed with /proc/sys/vm/munmap_unit_size
+ * tunable value.
+ */
+static void update_munmap_unit_size(void)
+{
+ munmap_unit_size = sysctl_munmap_unit_size;
+}
+
+/*
+ * sysctl handler which just sets sysctl_munmap_unit_size = the new value
+ * and then calls update_munmap_unit_size()
+ */
+int munmap_unit_size_handler(struct ctl_table *table, int write,
+ void __user *buffer, size_t *lenp, loff_t *ppos)
+{
+ int ret;
+
+ ret = proc_doulongvec_minmax(table, write, buffer, lenp, ppos);
+
+ update_munmap_unit_size();
+
+ return ret;
+}
+
+static int __init init_munmap_unit_size(void)
+{
+ update_munmap_unit_size();
+
+ return 0;
+}
+pure_initcall(init_munmap_unit_size);
--
1.7.3.4
--
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^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH V2 2/4] munmap: sysctl extension for tunable parameter
2011-06-27 13:41 [PATCH V2 0/4] munmap: Flexible mem unmap operation interface for scheduling latency Geunsik Lim
2011-06-27 13:41 ` [PATCH V2 1/4] munmap: mem unmap operation size handling Geunsik Lim
@ 2011-06-27 13:41 ` Geunsik Lim
2011-06-27 13:41 ` [PATCH V2 3/4] munmap: kbuild menu for munmap interface Geunsik Lim
2011-06-27 13:41 ` [PATCH V2 4/4] munmap: documentation of munmap operation interface Geunsik Lim
3 siblings, 0 replies; 5+ messages in thread
From: Geunsik Lim @ 2011-06-27 13:41 UTC (permalink / raw)
To: Ingo Molnar, Andrew Morton, Peter Zijlstra, Hugh Dickins,
Steven Rostedt
Cc: Thomas Gleixner, H. Peter Anvin, Darren Hart, linux-kernel,
linux-mm
From: Geunsik Lim <geunsik.lim@samsung.com>
Support sysctl interface(tunalbe parameter) to find a suitable munmap
operation unit at runtime favoringly
* sysctl: An interface for examining and dynamically changing munmap opearon
size parameters in Linux. In Linux, the sysctl is implemented as
a wrapper around file system routines that access contents of files
in the /proc
Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>
Acked-by: Hyunjin Choi <hj89.choi@samsung.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Steven Rostedt <rostedt@redhat.com>
CC: Hugh Dickins <hughd@google.com>
CC: Randy Dunlap <randy.dunlap@oracle.com>
CC: Ingo Molnar <mingo@elte.hu>
---
kernel/sysctl.c | 10 ++++++++++
1 files changed, 10 insertions(+), 0 deletions(-)
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index c0bb324..9b85041 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -56,6 +56,7 @@
#include <linux/kprobes.h>
#include <linux/pipe_fs_i.h>
#include <linux/oom.h>
+#include <linux/munmap_unit_size.h>
#include <asm/uaccess.h>
#include <asm/processor.h>
@@ -1278,6 +1279,15 @@ static struct ctl_table vm_table[] = {
.proc_handler = mmap_min_addr_handler,
},
#endif
+#ifdef CONFIG_MMU
+ {
+ .procname = "munmap_unit_size",
+ .data = &sysctl_munmap_unit_size,
+ .maxlen = sizeof(unsigned long),
+ .mode = 0644,
+ .proc_handler = munmap_unit_size_handler,
+ },
+#endif
#ifdef CONFIG_NUMA
{
.procname = "numa_zonelist_order",
--
1.7.3.4
--
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^ permalink raw reply related [flat|nested] 5+ messages in thread* [PATCH V2 3/4] munmap: kbuild menu for munmap interface
2011-06-27 13:41 [PATCH V2 0/4] munmap: Flexible mem unmap operation interface for scheduling latency Geunsik Lim
2011-06-27 13:41 ` [PATCH V2 1/4] munmap: mem unmap operation size handling Geunsik Lim
2011-06-27 13:41 ` [PATCH V2 2/4] munmap: sysctl extension for tunable parameter Geunsik Lim
@ 2011-06-27 13:41 ` Geunsik Lim
2011-06-27 13:41 ` [PATCH V2 4/4] munmap: documentation of munmap operation interface Geunsik Lim
3 siblings, 0 replies; 5+ messages in thread
From: Geunsik Lim @ 2011-06-27 13:41 UTC (permalink / raw)
To: Ingo Molnar, Andrew Morton, Peter Zijlstra, Hugh Dickins,
Steven Rostedt
Cc: Thomas Gleixner, H. Peter Anvin, Darren Hart, linux-kernel,
linux-mm
From: Geunsik Lim <geunsik.lim@samsung.com>
Support kbuild menu to select memory unmap operation size
at build time.
Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>
Acked-by: Hyunjin Choi <hj89.choi@samsung.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Steven Rostedt <rostedt@redhat.com>
CC: Hugh Dickins <hughd@google.com>
CC: Randy Dunlap <randy.dunlap@oracle.com>
CC: Ingo Molnar <mingo@elte.hu>
---
init/Kconfig | 70 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 84 insertions(+), 7 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index 56240e7..47283ed 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -557,6 +557,79 @@ config LOG_BUF_SHIFT
13 => 8 KB
12 => 4 KB
+config PREEMPT_OK_MUNMAP_RANGE
+ int "Memory unmap unit on preemptive mode (8 => 32KB)"
+ depends on !PREEMPT_NONE
+ range 8 2048
+ default 8
+ help
+ unmap_vmas(= unmap a range of memory covered by a list of vma) is
+ treading a delicate and uncomfortable line between high performance
+ and low latency.
+ This option improves performance at the expense of latency.
+
+ So although there may be no need to reschedule right now,
+ if we keep on gathering more and more memory without flushing,
+ we'll be very unresponsive when a reschedule is needed later on.
+
+ Consider the best suitable result between high performance and
+ low latency on preempt mode. Select optimal munmap size to return
+ memory space that is allocated by mmap system call.
+
+ For example, for recording mass files, if we try to unmap memory
+ that we allocated with 100MB for recording in embedded devices,
+ we have to wait for more than 3 seconds to change mode from play
+ mode to recording mode. This results from the unit of memory unmapped
+ size when we are recording mass files like camcorder particularly.
+
+ This value can be changed after boot using the
+ /proc/sys/vm/munmap_unit_size tunable.
+
+ Examples:
+ 2048 => 8,388,608 bytes : for straight-line efficiency
+ 1024 => 4,194,304 bytes
+ 512 => 2,097,152 bytes
+ 256 => 1,048,576 bytes
+ 128 => 524,288 bytes
+ 64 => 262,144 bytes
+ 32 => 131,072 bytes
+ 16 => 65,536 bytes
+ 8 => 32,768 bytes : for low-latency (*default)
+
+config PREEMPT_NO_MUNMAP_RANGE
+ int "Memory unmap unit on non-preempt mode (1024 => 4MB)"
+ depends on PREEMPT_NONE
+ range 8 2048
+ default 1024
+ help
+
+ unmap_vmas(= unmap a range of memory covered by a list of vma) is
+ treading a delicate and uncomfortable line between high performance
+ and low latency.
+ This option improves performance at the expense of latency.
+
+ So although there may be no need to reschedule right now,
+ if we keep on gathering more and more memory without flushing,
+ we'll be very unresponsive when a reschedule is needed later on.
+
+ Consider the best suitable result between high performance and
+ low latency on non-preempt mode. Select optimal munmap size to return
+ memory space that is allocated by mmap system call.
+
+ This value can be changed after boot using the
+ /proc/sys/vm/munmap_unit_size tunable.
+
+ Examples:
+ 2048 => 8,388,608 bytes : for straight-line efficiency
+ 1024 => 4,194,304 bytes (*default)
+ 512 => 2,097,152 bytes
+ 256 => 1,048,576 bytes
+ 128 => 524,288 bytes
+ 64 => 262,144 bytes
+ 32 => 131,072 bytes
+ 16 => 65,536 bytes
+ 8 => 32,768 bytes : for low-latency
+
#
# Architectures with an unreliable sched_clock() should select this:
#
--
1.7.3.4
--
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^ permalink raw reply related [flat|nested] 5+ messages in thread
* [PATCH V2 4/4] munmap: documentation of munmap operation interface
2011-06-27 13:41 [PATCH V2 0/4] munmap: Flexible mem unmap operation interface for scheduling latency Geunsik Lim
` (2 preceding siblings ...)
2011-06-27 13:41 ` [PATCH V2 3/4] munmap: kbuild menu for munmap interface Geunsik Lim
@ 2011-06-27 13:41 ` Geunsik Lim
3 siblings, 0 replies; 5+ messages in thread
From: Geunsik Lim @ 2011-06-27 13:41 UTC (permalink / raw)
To: Ingo Molnar, Andrew Morton, Peter Zijlstra, Hugh Dickins,
Steven Rostedt
Cc: Thomas Gleixner, H. Peter Anvin, Darren Hart, linux-kernel,
linux-mm
From: Geunsik Lim <geunsik.lim@samsung.com>
kernel documentation to utilize flexible memory unmap operation
interface for the ideal scheduler latency.
Signed-off-by: Geunsik Lim <geunsik.lim@samsung.com>
Acked-by: Hyunjin Choi <hj89.choi@samsung.com>
CC: Andrew Morton <akpm@linux-foundation.org>
CC: Peter Zijlstra <a.p.zijlstra@chello.nl>
CC: Steven Rostedt <rostedt@redhat.com>
CC: Hugh Dickins <hughd@google.com>
CC: Randy Dunlap <randy.dunlap@oracle.com>
CC: Ingo Molnar <mingo@elte.hu>
---
Documentation/sysctl/vm.txt | 36 ++++++++++++++++++++++++++++++++++++
MAINTAINERS | 7 +++++++
2 files changed, 43 insertions(+), 0 deletions(-)
diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt
index 30289fa..5d70098 100644
--- a/Documentation/sysctl/vm.txt
+++ b/Documentation/sysctl/vm.txt
@@ -40,6 +40,7 @@ Currently, these files are in /proc/sys/vm:
- min_slab_ratio
- min_unmapped_ratio
- mmap_min_addr
+- munmap_unit_size
- nr_hugepages
- nr_overcommit_hugepages
- nr_pdflush_threads
@@ -409,6 +410,42 @@ against future potential kernel bugs.
==============================================================
+munmap_unit_size
+
+unmap_vmas(= unmap a range of memory covered by a list of vma) is treading
+a delicate and uncomfortable line between high performance and low latency.
+We've chosen to improve performance at the expense of latency.
+
+So although there may be no need to reschedule right now,
+if we keep on gathering more and more memory without flushing,
+we'll be very unresponsive when a reschedule is needed later on.
+
+Consider the best suitable result between high performance and low latency
+on preemptive mode or non-preemptive mode. Select optimal munmap size to
+return memory space that is allocated by mmap system call.
+
+For example, for recording mass files, if we try to unmap memory that we
+allocated with 100MB for recording in embedded devices, we have to wait
+for more than 3 seconds to change mode from play mode to recording mode.
+This results from the unit of memory unmapped size when we are recording
+mass files like camcorder particularly.
+
+This value can be changed after boot using the
+/proc/sys/vm/munmap_unit_size tunable.
+
+Examples:
+ 2048 => 8,388,608 bytes : for straight-line efficiency
+ 1024 => 4,194,304 bytes
+ 512 => 2,097,152 bytes
+ 256 => 1,048,576 bytes
+ 128 => 524,288 bytes
+ 64 => 262,144 bytes
+ 32 => 131,072 bytes
+ 16 => 65,536 bytes
+ 8 => 32,768 bytes : for low-latency
+
+==============================================================
+
nr_hugepages
Change the minimum size of the hugepage pool.
diff --git a/MAINTAINERS b/MAINTAINERS
index 1380312..3f1960a 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -4128,6 +4128,12 @@ L: linux-mm@kvack.org
S: Maintained
F: mm/memcontrol.c
+MEMORY UNMAP OPERATION UNIT INTERFACE
+M: Geunsik Lim <geunsik.lim@samsung.com>
+S: Maintained
+F: mm/munmap_unit_size.c
+F: include/linux/munmap_unit_size.h
+
MEMORY TECHNOLOGY DEVICES (MTD)
M: David Woodhouse <dwmw2@infradead.org>
L: linux-mtd@lists.infradead.org
--
1.7.3.4
--
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^ permalink raw reply related [flat|nested] 5+ messages in thread