Commit 8abddd96 authored by Nicholas Piggin's avatar Nicholas Piggin Committed by Michael Ellerman
Browse files

powerpc/64s/radix: Enable huge vmalloc mappings 



This reduces TLB misses by nearly 30x on a `git diff` workload on a
2-node POWER9 (59,800 -> 2,100) and reduces CPU cycles by 0.54%, due
to vfs hashes being allocated with 2MB pages.

Signed-off-by: default avatarNicholas Piggin <npiggin@gmail.com>
Reviewed-by: default avatarChristophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Signed-off-by: default avatarMichael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210503091755.613393-1-npiggin@gmail.com
parent 562d1e20

Documentation/admin-guide/kernel-parameters.txt

+2 −0
Original line number Diff line number Diff line
@@ -3251,6 +3251,8 @@ 


	nohugeiomap	[KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.



	nohugevmalloc	[PPC] Disable kernel huge vmalloc mappings.



	nosmt		[KNL,S390] Disable symmetric multithreading (SMT).

			Equivalent to smt=1.

arch/powerpc/Kconfig

+1 −0
Original line number Diff line number Diff line
@@ -185,6 +185,7 @@ config PPC 
	select GENERIC_VDSO_TIME_NS

	select HAVE_ARCH_AUDITSYSCALL

	select HAVE_ARCH_HUGE_VMAP		if PPC_BOOK3S_64 && PPC_RADIX_MMU

	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP

	select HAVE_ARCH_JUMP_LABEL

	select HAVE_ARCH_JUMP_LABEL_RELATIVE

	select HAVE_ARCH_KASAN			if PPC32 && PPC_PAGE_SHIFT <= 14

arch/powerpc/kernel/module.c

+13 −5
Original line number Diff line number Diff line
@@ -8,6 +8,7 @@ 
#include <linux/moduleloader.h>

#include <linux/err.h>

#include <linux/vmalloc.h>

#include <linux/mm.h>

#include <linux/bug.h>

#include <asm/module.h>

#include <linux/uaccess.h>
@@ -88,17 +89,22 @@ int module_finalize(const Elf_Ehdr *hdr, 
	return 0;

}



#ifdef MODULES_VADDR

static __always_inline void *

__module_alloc(unsigned long size, unsigned long start, unsigned long end)

{

	return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL,

				    PAGE_KERNEL_EXEC, VM_FLUSH_RESET_PERMS, NUMA_NO_NODE,

				    __builtin_return_address(0));

	/*

	 * Don't do huge page allocations for modules yet until more testing

	 * is done. STRICT_MODULE_RWX may require extra work to support this

	 * too.

	 */

	return __vmalloc_node_range(size, 1, start, end, GFP_KERNEL, PAGE_KERNEL_EXEC,

				    VM_FLUSH_RESET_PERMS | VM_NO_HUGE_VMAP,

				    NUMA_NO_NODE, __builtin_return_address(0));

}



void *module_alloc(unsigned long size)

{

#ifdef MODULES_VADDR

	unsigned long limit = (unsigned long)_etext - SZ_32M;

	void *ptr = NULL;
@@ -112,5 +118,7 @@ void *module_alloc(unsigned long size) 
		ptr = __module_alloc(size, MODULES_VADDR, MODULES_END);



	return ptr;

}

#else

	return __module_alloc(size, VMALLOC_START, VMALLOC_END);

#endif

}