| Message ID | 20211015210336.gen3tib33ig5q2md@linutronix.de (mailing list archive) |
|---|---|
| State | New |
| Headers | show |
| Series | mm: Allow only SLUB on PREEMPT_RT | expand |
On 10/15/21 11:03 PM, Sebastian Andrzej Siewior wrote: > From: Ingo Molnar <mingo@kernel.org> > Date: Fri, 3 Jul 2009 08:44:03 -0500 > > Memory allocators may disable interrupts or preemption as part of the > allocation and freeing process. For PREEMPT_RT it is important that > these sections remain deterministic and short and therefore don't depend > on the size of the memory to allocate/ free or the inner state of the > algorithm. > > Until v3.12-RT the SLAB allocator was an option but involved several > changes to meet all the requirements. The SLUB design fits better with > PREEMPT_RT model and so the SLAB patches were dropped in the 3.12-RT > patchset. Comparing the two allocator, SLUB outperformed SLAB in both > throughput (time needed to allocate and free memory) and the maximal > latency of the system measured with cyclictest during hackbench. > > SLOB was never evaluated since it was unlikely that it preforms better > than SLAB. During a quick test, the kernel crashed with SLOB enabled > during boot. > > Disable SLAB and SLOB on PREEMPT_RT. > > [bigeasy: commit description.] > > Signed-off-by: Ingo Molnar <mingo@kernel.org> > Signed-off-by: Thomas Gleixner <tglx@linutronix.de> > Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de> Acked-by: Vlastimil Babka <vbabka@suse.cz> > --- > init/Kconfig | 2 ++ > 1 file changed, 2 insertions(+) > > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -1896,6 +1896,7 @@ choice > > config SLAB > bool "SLAB" > + depends on !PREEMPT_RT > select HAVE_HARDENED_USERCOPY_ALLOCATOR > help > The regular slab allocator that is established and known to work > @@ -1916,6 +1917,7 @@ config SLUB > config SLOB > depends on EXPERT > bool "SLOB (Simple Allocator)" > + depends on !PREEMPT_RT > help > SLOB replaces the stock allocator with a drastically simpler > allocator. SLOB is generally more space efficient but >
--- a/init/Kconfig +++ b/init/Kconfig @@ -1896,6 +1896,7 @@ choice config SLAB bool "SLAB" + depends on !PREEMPT_RT select HAVE_HARDENED_USERCOPY_ALLOCATOR help The regular slab allocator that is established and known to work @@ -1916,6 +1917,7 @@ config SLUB config SLOB depends on EXPERT bool "SLOB (Simple Allocator)" + depends on !PREEMPT_RT help SLOB replaces the stock allocator with a drastically simpler allocator. SLOB is generally more space efficient but