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authorMatt Mackall <mpm@selenic.com>2006-01-08 01:01:45 -0800
committerLinus Torvalds <torvalds@g5.osdl.org>2006-01-08 20:13:41 -0800
commit10cef6029502915bdb3cf0821d425cf9dc30c817 (patch)
tree2c9dfef95d58b64dcf4cdf3c32b18164928b438e /init
parent[PATCH] slob: introduce mm/util.c for shared functions (diff)
downloadlinux-dev-10cef6029502915bdb3cf0821d425cf9dc30c817.tar.xz
linux-dev-10cef6029502915bdb3cf0821d425cf9dc30c817.zip
[PATCH] slob: introduce the SLOB allocator
configurable replacement for slab allocator This adds a CONFIG_SLAB option under CONFIG_EMBEDDED. When CONFIG_SLAB is disabled, the kernel falls back to using the 'SLOB' allocator. SLOB is a traditional K&R/UNIX allocator with a SLAB emulation layer, similar to the original Linux kmalloc allocator that SLAB replaced. It's signicantly smaller code and is more memory efficient. But like all similar allocators, it scales poorly and suffers from fragmentation more than SLAB, so it's only appropriate for small systems. It's been tested extensively in the Linux-tiny tree. I've also stress-tested it with make -j 8 compiles on a 3G SMP+PREEMPT box (not recommended). Here's a comparison for otherwise identical builds, showing SLOB saving nearly half a megabyte of RAM: $ size vmlinux* text data bss dec hex filename 3336372 529360 190812 4056544 3de5e0 vmlinux-slab 3323208 527948 190684 4041840 3dac70 vmlinux-slob $ size mm/{slab,slob}.o text data bss dec hex filename 13221 752 48 14021 36c5 mm/slab.o 1896 52 8 1956 7a4 mm/slob.o /proc/meminfo: SLAB SLOB delta MemTotal: 27964 kB 27980 kB +16 kB MemFree: 24596 kB 25092 kB +496 kB Buffers: 36 kB 36 kB 0 kB Cached: 1188 kB 1188 kB 0 kB SwapCached: 0 kB 0 kB 0 kB Active: 608 kB 600 kB -8 kB Inactive: 808 kB 812 kB +4 kB HighTotal: 0 kB 0 kB 0 kB HighFree: 0 kB 0 kB 0 kB LowTotal: 27964 kB 27980 kB +16 kB LowFree: 24596 kB 25092 kB +496 kB SwapTotal: 0 kB 0 kB 0 kB SwapFree: 0 kB 0 kB 0 kB Dirty: 4 kB 12 kB +8 kB Writeback: 0 kB 0 kB 0 kB Mapped: 560 kB 556 kB -4 kB Slab: 1756 kB 0 kB -1756 kB CommitLimit: 13980 kB 13988 kB +8 kB Committed_AS: 4208 kB 4208 kB 0 kB PageTables: 28 kB 28 kB 0 kB VmallocTotal: 1007312 kB 1007312 kB 0 kB VmallocUsed: 48 kB 48 kB 0 kB VmallocChunk: 1007264 kB 1007264 kB 0 kB (this work has been sponsored in part by CELF) From: Ingo Molnar <mingo@elte.hu> Fix 32-bitness bugs in mm/slob.c. Signed-off-by: Matt Mackall <mpm@selenic.com> Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'init')
-rw-r--r--init/Kconfig13
1 files changed, 13 insertions, 0 deletions
diff --git a/init/Kconfig b/init/Kconfig
index ba42f3793a84..0c9932f9f06b 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -380,6 +380,15 @@ config CC_ALIGN_JUMPS
no dummy operations need be executed.
Zero means use compiler's default.
+config SLAB
+ default y
+ bool "Use full SLAB allocator" if EMBEDDED
+ help
+ Disabling this replaces the advanced SLAB allocator and
+ kmalloc support with the drastically simpler SLOB allocator.
+ SLOB is more space efficient but does not scale well and is
+ more susceptible to fragmentation.
+
endmenu # General setup
config TINY_SHMEM
@@ -391,6 +400,10 @@ config BASE_SMALL
default 0 if BASE_FULL
default 1 if !BASE_FULL
+config SLOB
+ default !SLAB
+ bool
+
menu "Loadable module support"
config MODULES