From 03dc2ac5b10ee9ab68090a486d54a7d53492c86d 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 (cherry picked from commit bcf1647d0899666f0fb90d176abf63bae22abb7c) Signed-off-by: Alex Shi Conflicts: drivers/staging/zsmalloc/Kconfig mm/Kconfig mm/Makefile Conflicts solutions: only move zsmalloc to mm/, skip unrelated cma/zbud/zswap --- drivers/staging/Kconfig | 2 -- drivers/staging/Makefile | 1 - drivers/staging/zram/zram_drv.h | 3 +-- drivers/staging/zsmalloc/Makefile | 3 --- .../zsmalloc => include/linux}/zsmalloc.h | 0 mm/Kconfig | 25 +++++++++++++++++++ mm/Makefile | 1 + .../zsmalloc/zsmalloc-main.c => mm/zsmalloc.c | 3 +-- 8 files changed, 28 insertions(+), 10 deletions(-) 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 aefe820a8005..60585217481f 100644 --- a/drivers/staging/Kconfig +++ b/drivers/staging/Kconfig @@ -72,8 +72,6 @@ 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 415772ea306d..29aaeaa283eb 100644 --- a/drivers/staging/Makefile +++ b/drivers/staging/Makefile @@ -31,7 +31,6 @@ 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 97a3acf6ab76..d8f6596513c3 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/Makefile b/drivers/staging/zsmalloc/Makefile deleted file mode 100644 index b134848a590d..000000000000 --- a/drivers/staging/zsmalloc/Makefile +++ /dev/null @@ -1,3 +0,0 @@ -zsmalloc-y := zsmalloc-main.o - -obj-$(CONFIG_ZSMALLOC) += zsmalloc.o diff --git a/drivers/staging/zsmalloc/zsmalloc.h b/include/linux/zsmalloc.h similarity index 100% rename from drivers/staging/zsmalloc/zsmalloc.h rename to include/linux/zsmalloc.h diff --git a/mm/Kconfig b/mm/Kconfig index e742d06285b7..86919079b64c 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -477,3 +477,28 @@ config FRONTSWAP and swap data is stored as normal on the matching swap device. If unsure, say Y to enable frontswap. + +config ZSMALLOC + bool "Memory allocator for compressed pages" + depends on MMU + default n + help + zsmalloc is a slab-based memory allocator designed to store + compressed RAM pages. zsmalloc uses virtual memory mapping + in order to reduce fragmentation. However, this results in a + non-standard allocator interface where a handle, not a pointer, is + returned by an alloc(). This handle must be mapped in order to + access the allocated space. + +config PGTABLE_MAPPING + bool "Use page table mapping to access object in zsmalloc" + depends on ZSMALLOC + help + By default, zsmalloc uses a copy-based object mapping method to + access allocations that span two pages. However, if a particular + architecture (ex, ARM) performs VM mapping faster than copying, + then you should select this. This causes zsmalloc to use page table + mapping rather than copying for object mapping. + + You can check speed with zsmalloc benchmark[1]. + [1] https://github.com/spartacus06/zsmalloc diff --git a/mm/Makefile b/mm/Makefile index 72c5acb9345f..b5ae0b0cc26c 100644 --- a/mm/Makefile +++ b/mm/Makefile @@ -58,3 +58,4 @@ obj-$(CONFIG_DEBUG_KMEMLEAK) += kmemleak.o obj-$(CONFIG_DEBUG_KMEMLEAK_TEST) += kmemleak-test.o obj-$(CONFIG_CLEANCACHE) += cleancache.o obj-$(CONFIG_MEMORY_ISOLATION) += page_isolation.o +obj-$(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 288f58252a18..6ad98bb06411 100644 --- a/drivers/staging/zsmalloc/zsmalloc-main.c +++ b/mm/zsmalloc.c @@ -78,8 +78,7 @@ #include #include #include - -#include "zsmalloc.h" +#include /* * This must be power of 2 and greater than of equal to sizeof(link_free). -- 2.34.1