For tiny systems that have used SLOB until now, SLUB might be impractical due to its higher memory usage. To help with that, introduce an option CONFIG_SLUB_TINY that modifies SLUB to use less memory. This is done by sacrificing scalability, security and debugging features, therefore not recommended for any system with more than 16MB RAM. This commit introduces the option and uses it to set other related options in a way that reduces memory usage. Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx> --- mm/Kconfig | 21 +++++++++++++++++---- mm/Kconfig.debug | 2 +- 2 files changed, 18 insertions(+), 5 deletions(-) diff --git a/mm/Kconfig b/mm/Kconfig index 57e1d8c5b505..5941cb34e30d 100644 --- a/mm/Kconfig +++ b/mm/Kconfig @@ -230,6 +230,19 @@ config SLOB endchoice +config SLUB_TINY + bool "Configure SLUB for minimal memory footprint" + depends on SLUB && EXPERT + select SLAB_MERGE_DEFAULT + help + Configures the SLUB allocator in a way to achieve minimal memory + footprint, sacrificing scalability, debugging and other features. + This is intended only for the smallest system that had used the + SLOB allocator and is not recommended for systems with more than + 16MB RAM. + + If unsure, say N. + config SLAB_MERGE_DEFAULT bool "Allow slab caches to be merged" default y @@ -247,7 +260,7 @@ config SLAB_MERGE_DEFAULT config SLAB_FREELIST_RANDOM bool "Randomize slab freelist" - depends on SLAB || SLUB + depends on SLAB || SLUB && !SLUB_TINY help Randomizes the freelist order used on creating new pages. This security feature reduces the predictability of the kernel slab @@ -255,7 +268,7 @@ config SLAB_FREELIST_RANDOM config SLAB_FREELIST_HARDENED bool "Harden slab freelist metadata" - depends on SLAB || SLUB + depends on SLAB || SLUB && !SLUB_TINY help Many kernel heap attacks try to target slab cache metadata and other infrastructure. This options makes minor performance @@ -267,7 +280,7 @@ config SLAB_FREELIST_HARDENED config SLUB_STATS default n bool "Enable SLUB performance statistics" - depends on SLUB && SYSFS + depends on SLUB && SYSFS && !SLUB_TINY help SLUB statistics are useful to debug SLUBs allocation behavior in order find ways to optimize the allocator. This should never be @@ -279,7 +292,7 @@ config SLUB_STATS config SLUB_CPU_PARTIAL default y - depends on SLUB && SMP + depends on SLUB && SMP && !SLUB_TINY bool "SLUB per cpu partial cache" help Per cpu partial caches accelerate objects allocation and freeing diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug index ce8dded36de9..fca699ad1fb0 100644 --- a/mm/Kconfig.debug +++ b/mm/Kconfig.debug @@ -56,7 +56,7 @@ config DEBUG_SLAB config SLUB_DEBUG default y bool "Enable SLUB debugging support" if EXPERT - depends on SLUB && SYSFS + depends on SLUB && SYSFS && !SLUB_TINY select STACKDEPOT if STACKTRACE_SUPPORT help SLUB has extensive debug support features. Disabling these can -- 2.38.1
