I recently introduced memset32() / memset64(). I've done implementations for x86 & ARM; akpm has agreed to take the patchset through his tree. Do you fancy doing a powerpc version? Minchan Kim got a 7% performance increase with zram from switching to the optimised version on x86.
Here's the development git tree: http://git.infradead.org/users/willy/linux-dax.git/shortlog/refs/heads/memfill (most recent 7 commits) ARM probably offers the best model for you to work from; it's basically just a case of jumping into the middle of your existing memset loop. It was only three instructions to add support to ARM, but I don't know PowerPC well enough to understand how your existing memset works. I'd start with something like this ... note that you don't have to implement memset64 on 32-bit; I only did it on ARM because it was free. It doesn't look free for you as you only store one register each time around the loop in the 32-bit memset implementation: 1: stwu r4,4(r6) bdnz 1b (wouldn't you get better performance on 32-bit powerpc by unrolling that loop like you do on 64-bit?) diff --git a/arch/powerpc/include/asm/string.h b/arch/powerpc/include/asm/string.h index da3cdffca440..c02392fced98 100644 --- a/arch/powerpc/include/asm/string.h +++ b/arch/powerpc/include/asm/string.h @@ -6,6 +6,7 @@ #define __HAVE_ARCH_STRNCPY #define __HAVE_ARCH_STRNCMP #define __HAVE_ARCH_MEMSET +#define __HAVE_ARCH_MEMSET_PLUS #define __HAVE_ARCH_MEMCPY #define __HAVE_ARCH_MEMMOVE #define __HAVE_ARCH_MEMCMP @@ -23,6 +24,18 @@ extern void * memmove(void *,const void *,__kernel_size_t); extern int memcmp(const void *,const void *,__kernel_size_t); extern void * memchr(const void *,int,__kernel_size_t); +extern void *__memset32(uint32_t *, uint32_t v, __kernel_size_t); +static inline void *memset32(uint32_t *p, uint32_t v, __kernel_size_t n) +{ + return __memset32(p, v, n * 4); +} + +extern void *__memset64(uint64_t *, uint64_t v, __kernel_size_t); +static inline void *memset64(uint64_t *p, uint64_t v, __kernel_size_t n) +{ + return __memset64(p, v, n * 8); +} + #endif /* __KERNEL__ */ #endif /* _ASM_POWERPC_STRING_H */