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authorMinchan Kim <minchan@kernel.org>2014-01-30 15:45:50 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2014-01-30 16:56:55 -0800
commitbcf1647d0899666f0fb90d176abf63bae22abb7c (patch)
tree6682b0feec718f594829770b4287afa2da266a0f
parent73f945505b9bf798d8c3ee830cb330dd6d7fb4c7 (diff)
downloadlinux-bcf1647d0899666f0fb90d176abf63bae22abb7c.tar.gz
zsmalloc: move it under mm
This patch moves zsmalloc under mm directory. Before that, description will explain why we have needed custom allocator. Zsmalloc is a new slab-based memory allocator for storing compressed pages. It is designed for low fragmentation and high allocation success rate on large object, but <= PAGE_SIZE allocations. zsmalloc differs from the kernel slab allocator in two primary ways to achieve these design goals. zsmalloc never requires high order page allocations to back slabs, or "size classes" in zsmalloc terms. Instead it allows multiple single-order pages to be stitched together into a "zspage" which backs the slab. This allows for higher allocation success rate under memory pressure. Also, zsmalloc allows objects to span page boundaries within the zspage. This allows for lower fragmentation than could be had with the kernel slab allocator for objects between PAGE_SIZE/2 and PAGE_SIZE. With the kernel slab allocator, if a page compresses to 60% of it original size, the memory savings gained through compression is lost in fragmentation because another object of the same size can't be stored in the leftover space. This ability to span pages results in zsmalloc allocations not being directly addressable by the user. The user is given an non-dereferencable handle in response to an allocation request. That handle must be mapped, using zs_map_object(), which returns a pointer to the mapped region that can be used. The mapping is necessary since the object data may reside in two different noncontigious pages. The zsmalloc fulfills the allocation needs for zram perfectly [sjenning@linux.vnet.ibm.com: borrow Seth's quote] Signed-off-by: Minchan Kim <minchan@kernel.org> Acked-by: Nitin Gupta <ngupta@vflare.org> Reviewed-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com> Cc: Bob Liu <bob.liu@oracle.com> Cc: Greg Kroah-Hartman <gregkh@linuxfoundation.org> Cc: Hugh Dickins <hughd@google.com> Cc: Jens Axboe <axboe@kernel.dk> Cc: Luigi Semenzato <semenzato@google.com> Cc: Mel Gorman <mgorman@suse.de> Cc: Pekka Enberg <penberg@kernel.org> Cc: Rik van Riel <riel@redhat.com> Cc: Seth Jennings <sjenning@linux.vnet.ibm.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
-rw-r--r--drivers/staging/Kconfig2
-rw-r--r--drivers/staging/Makefile1
-rw-r--r--drivers/staging/zram/zram_drv.h3
-rw-r--r--drivers/staging/zsmalloc/Kconfig24
-rw-r--r--drivers/staging/zsmalloc/Makefile3
-rw-r--r--include/linux/zsmalloc.h (renamed from drivers/staging/zsmalloc/zsmalloc.h)0
-rw-r--r--mm/Kconfig25
-rw-r--r--mm/Makefile1
-rw-r--r--mm/zsmalloc.c (renamed from drivers/staging/zsmalloc/zsmalloc-main.c)3
9 files changed, 28 insertions, 34 deletions
diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig
index 4bb6b11166b..120d2fa9e53 100644
--- a/drivers/staging/Kconfig
+++ b/drivers/staging/Kconfig
@@ -76,8 +76,6 @@ source "drivers/staging/sep/Kconfig"
source "drivers/staging/iio/Kconfig"
-source "drivers/staging/zsmalloc/Kconfig"
-
source "drivers/staging/zram/Kconfig"
source "drivers/staging/wlags49_h2/Kconfig"
diff --git a/drivers/staging/Makefile b/drivers/staging/Makefile
index 9f07e5e1609..cb19d0afa0d 100644
--- a/drivers/staging/Makefile
+++ b/drivers/staging/Makefile
@@ -33,7 +33,6 @@ obj-$(CONFIG_VME_BUS) += vme/
obj-$(CONFIG_DX_SEP) += sep/
obj-$(CONFIG_IIO) += iio/
obj-$(CONFIG_ZRAM) += zram/
-obj-$(CONFIG_ZSMALLOC) += zsmalloc/
obj-$(CONFIG_WLAGS49_H2) += wlags49_h2/
obj-$(CONFIG_WLAGS49_H25) += wlags49_h25/
obj-$(CONFIG_FB_SM7XX) += sm7xxfb/
diff --git a/drivers/staging/zram/zram_drv.h b/drivers/staging/zram/zram_drv.h
index 97a3acf6ab7..d8f6596513c 100644
--- a/drivers/staging/zram/zram_drv.h
+++ b/drivers/staging/zram/zram_drv.h
@@ -17,8 +17,7 @@
#include <linux/spinlock.h>
#include <linux/mutex.h>
-
-#include "../zsmalloc/zsmalloc.h"
+#include <linux/zsmalloc.h>
/*
* Some arbitrary value. This is just to catch
diff --git a/drivers/staging/zsmalloc/Kconfig b/drivers/staging/zsmalloc/Kconfig
deleted file mode 100644
index 9d1f2a24ad6..00000000000
--- a/drivers/staging/zsmalloc/Kconfig
+++ /dev/null
@@ -1,24 +0,0 @@
-config ZSMALLOC
- bool "Memory allocator for compressed pages"
- depends on MMU
- default n
- help
- zsmalloc is a slab-based memory allocator designed to store
- compressed RAM pages. zsmalloc uses virtual memory mapping
- in order to reduce fragmentation. However, this results in a
- non-standard allocator interface where a handle, not a pointer, is
- returned by an alloc(). This handle must be mapped in order to
- access the allocated space.
-
-config PGTABLE_MAPPING
- bool "Use page table mapping to access object in zsmalloc"
- depends on ZSMALLOC
- help
- By default, zsmalloc uses a copy-based object mapping method to
- access allocations that span two pages. However, if a particular
- architecture (ex, ARM) performs VM mapping faster than copying,
- then you should select this. This causes zsmalloc to use page table
- mapping rather than copying for object mapping.
-
- You can check speed with zsmalloc benchmark[1].
- [1] https://github.com/spartacus06/zsmalloc
diff --git a/drivers/staging/zsmalloc/Makefile b/drivers/staging/zsmalloc/Makefile
deleted file mode 100644
index b134848a590..00000000000
--- a/drivers/staging/zsmalloc/Makefile
+++ /dev/null
@@ -1,3 +0,0 @@
-zsmalloc-y := zsmalloc-main.o
-
-obj-$(CONFIG_ZSMALLOC) += zsmalloc.o
diff --git a/drivers/staging/zsmalloc/zsmalloc.h b/include/linux/zsmalloc.h
index c2eb174b97e..c2eb174b97e 100644
--- a/drivers/staging/zsmalloc/zsmalloc.h
+++ b/include/linux/zsmalloc.h
diff --git a/mm/Kconfig b/mm/Kconfig
index 723bbe04a0b..2d9f1504d75 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -552,3 +552,28 @@ config MEM_SOFT_DIRTY
it can be cleared by hands.
See Documentation/vm/soft-dirty.txt for more details.
+
+config ZSMALLOC
+ bool "Memory allocator for compressed pages"
+ depends on MMU
+ default n
+ help
+ zsmalloc is a slab-based memory allocator designed to store
+ compressed RAM pages. zsmalloc uses virtual memory mapping
+ in order to reduce fragmentation. However, this results in a
+ non-standard allocator interface where a handle, not a pointer, is
+ returned by an alloc(). This handle must be mapped in order to
+ access the allocated space.
+
+config PGTABLE_MAPPING
+ bool "Use page table mapping to access object in zsmalloc"
+ depends on ZSMALLOC
+ help
+ By default, zsmalloc uses a copy-based object mapping method to
+ access allocations that span two pages. However, if a particular
+ architecture (ex, ARM) performs VM mapping faster than copying,
+ then you should select this. This causes zsmalloc to use page table
+ mapping rather than copying for object mapping.
+
+ You can check speed with zsmalloc benchmark[1].
+ [1] https://github.com/spartacus06/zsmalloc
diff --git a/mm/Makefile b/mm/Makefile
index 305d10acd08..310c90a0926 100644
--- a/mm/Makefile
+++ b/mm/Makefile
@@ -60,3 +60,4 @@ obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o
obj-$(CONFIG_CLEANCACHE) += cleancache.o
obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o
obj-$(CONFIG_ZBUD) += zbud.o
+obj-$(CONFIG_ZSMALLOC) += zsmalloc.o
diff --git a/drivers/staging/zsmalloc/zsmalloc-main.c b/mm/zsmalloc.c
index 7660c87d8b2..5d42adfcb67 100644
--- a/drivers/staging/zsmalloc/zsmalloc-main.c
+++ b/mm/zsmalloc.c
@@ -90,8 +90,7 @@
#include <linux/hardirq.h>
#include <linux/spinlock.h>
#include <linux/types.h>
-
-#include "zsmalloc.h"
+#include <linux/zsmalloc.h>
/*
* This must be power of 2 and greater than of equal to sizeof(link_free).