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powerpc/64s/radix: Enable huge vmalloc mappings

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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: Nicholas Piggin <npiggin@gmail.com>
Reviewed-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Acked-by: Michael Ellerman <mpe@ellerman.id.au>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210503091755.613393-1-npiggin@gmail.com
This commit is contained in:
Nicholas Piggin 2021-05-03 19:17:55 +10:00 committed by Michael Ellerman
parent 562d1e207d
commit 8abddd968a
3 changed files with 16 additions and 5 deletions
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2
Documentation/admin-guide/kernel-parameters.txt
View file

@ -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.

1
arch/powerpc/Kconfig
View file

@ -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

18
arch/powerpc/kernel/module.c
View file

@ -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
}