From bcf1647d0899666f0fb90d176abf63bae22abb7c Mon Sep 17 00:00:00 2001 From: Minchan Kim Date: Thu, 30 Jan 2014 15:45:50 -0800 Subject: [PATCH] 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 Acked-by: Nitin Gupta Reviewed-by: Konrad Rzeszutek Wilk Cc: Bob Liu Cc: Greg Kroah-Hartman Cc: Hugh Dickins Cc: Jens Axboe Cc: Luigi Semenzato Cc: Mel Gorman Cc: Pekka Enberg Cc: Rik van Riel Cc: Seth Jennings Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- drivers/staging/Kconfig | 2 -- drivers/staging/Makefile | 1 - drivers/staging/zram/zram_drv.h | 3 +-- drivers/staging/zsmalloc/Kconfig | 24 --------------------- drivers/staging/zsmalloc/Makefile | 3 --- .../staging/zsmalloc => include/linux}/zsmalloc.h | 0 mm/Kconfig | 25 ++++++++++++++++++++++ mm/Makefile | 1 + .../zsmalloc/zsmalloc-main.c => mm/zsmalloc.c | 3 +-- 9 files changed, 28 insertions(+), 34 deletions(-) delete mode 100644 drivers/staging/zsmalloc/Kconfig delete mode 100644 drivers/staging/zsmalloc/Makefile rename {drivers/staging/zsmalloc => include/linux}/zsmalloc.h (100%) rename drivers/staging/zsmalloc/zsmalloc-main.c => mm/zsmalloc.c (99%) diff --git a/drivers/staging/Kconfig b/drivers/staging/Kconfig index 4bb6b11..120d2fa 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 9f07e5e..cb19d0a 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 97a3acf..d8f6596 100644 --- a/drivers/staging/zram/zram_drv.h +++ b/drivers/staging/zram/zram_drv.h @@ -17,8 +17,7 @@ #include #include - -#include "../zsmalloc/zsmalloc.h" +#include /* * 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 9d1f2a2..0000000 --- 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 b134848..0000000 --- a/drivers/staging/zsmalloc/Makefile +++ /dev/null @@ -1,3 +0,0 @@ -zsmalloc-y := zsmalloc-main.o - -obj-$(CONFIG_ZSMALLOC) += zsmalloc.o diff --git a/drivers/staging/zsmalloc/zsmalloc.h b/include/linux/zsmalloc.h similarity index 100% rename from drivers/staging/zsmalloc/zsmalloc.h rename to include/linux/zsmalloc.h diff --git a/mm/Kconfig b/mm/Kconfig index 723bbe0..2d9f150 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -552,3 +552,28 @@ config MEM_SOFT_DIRTY it can be cleared by hands. See Documentation/vm/soft-dirty.txt for more details. + +config ZSMALLOC + bool "Memory allocator for compressed pages" + depends on MMU + default n + help + zsmalloc is a slab-based memory allocator designed to store + compressed RAM pages. zsmalloc uses virtual memory mapping + in order to reduce fragmentation. However, this results in a + non-standard allocator interface where a handle, not a pointer, is + returned by an alloc(). This handle must be mapped in order to + access the allocated space. + +config PGTABLE_MAPPING + bool "Use page table mapping to access object in zsmalloc" + depends on ZSMALLOC + help + By default, zsmalloc uses a copy-based object mapping method to + access allocations that span two pages. However, if a particular + architecture (ex, ARM) performs VM mapping faster than copying, + then you should select this. This causes zsmalloc to use page table + mapping rather than copying for object mapping. + + You can check speed with zsmalloc benchmark[1]. + [1] https://github.com/spartacus06/zsmalloc diff --git a/mm/Makefile b/mm/Makefile index 305d10a..310c90a 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -60,3 +60,4 @@ obj-$(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 similarity index 99% rename from drivers/staging/zsmalloc/zsmalloc-main.c rename to mm/zsmalloc.c index 7660c87..5d42adf 100644 --- a/drivers/staging/zsmalloc/zsmalloc-main.c +++ b/mm/zsmalloc.c @@ -90,8 +90,7 @@ #include #include #include - -#include "zsmalloc.h" +#include /* * This must be power of 2 and greater than of equal to sizeof(link_free). -- 2.7.4