linux-arm.git - Russell King's ARM Linux kernel tree

Age	Commit message (Collapse)	Author
2022-09-28	powerpc/64s: Make POWER10 and later use pause_short in cpu_relax loops	Nicholas Piggin
	We want to move away from using SMT priority updates for cpu_relax, and use a 'wait' instruction which is similar to x86. As well as being a much better fit for what everybody else uses and tests with, priority nops are stateful which is nasty (interrupts have to consider they might be taken at a different priority), and they're expensive to execute, similar to a mtSPR which can effect other threads in the pipe. This has shown to give results that are less affected by code alignment on benchmarks that cause a lot of spin waiting (e.g., rwsem contention on unixbench filesystem benchmarks) on POWER10. QEMU TCG only supports this instruction correctly since v7.1, versions without the fix may cause hangs whne running POWER10 CPUs. Reviewed-by: Segher Boessenkool <segher@kernel.crashing.org> Signed-off-by: Nicholas Piggin <npiggin@gmail.com> [mpe: Fix checkpatch warnings RE the macros] Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20220920122259.363092-2-npiggin@gmail.com
2021-08-27	powerpc: Redefine HMT_xxx macros as empty on PPC32	Christophe Leroy
	HMT_xxx macros are macros for adjusting thread priority (hardware multi-threading) are macros inherited from PPC64 via commit 5f7c690728ac ("[PATCH] powerpc: Merged ppc_asm.h") Those instructions are pointless on PPC32, but some common fonctions like arch_cpu_idle() use them. So make them empty on PPC32 to avoid those instructions. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/c5a07fadea33d640ad10cecf0ac8faaec1c524e0.1629898474.git.christophe.leroy@csgroup.eu
2020-12-04	powerpc/processor: Move cpu_relax() into asm/vdso/processor.h	Christophe Leroy
	cpu_relax() need to be in asm/vdso/processor.h to be used by the C VDSO generic library. Move it there. Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu> Signed-off-by: Michael Ellerman <mpe@ellerman.id.au> Link: https://lore.kernel.org/r/20201126131006.2431205-2-mpe@ellerman.id.au