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author | Christophe Leroy <christophe.leroy@c-s.fr> | 2016-03-07 18:44:37 +0100 |
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committer | Scott Wood <oss@buserror.net> | 2016-03-09 10:44:18 -0600 |
commit | 7e393220b6e1ecfa5520d1b2ca31150b7588f458 (patch) | |
tree | dcea05372297033d1327befd4cfa60dfb24141fb /arch/powerpc/include/asm/checksum.h | |
parent | ac6082dd32da2774241a75f1fca2de71a39ef768 (diff) | |
download | linux-7e393220b6e1ecfa5520d1b2ca31150b7588f458.tar.bz2 |
powerpc: optimise csum_partial() call when len is constant
csum_partial is often called for small fixed length packets
for which it is suboptimal to use the generic csum_partial()
function.
For instance, in my configuration, I got:
* One place calling it with constant len 4
* Seven places calling it with constant len 8
* Three places calling it with constant len 14
* One place calling it with constant len 20
* One place calling it with constant len 24
* One place calling it with constant len 32
This patch renames csum_partial() to __csum_partial() and
implements csum_partial() as a wrapper inline function which
* uses csum_add() for small 16bits multiple constant length
* uses ip_fast_csum() for other 32bits multiple constant
* uses __csum_partial() in all other cases
Signed-off-by: Christophe Leroy <christophe.leroy@c-s.fr>
Signed-off-by: Scott Wood <oss@buserror.net>
Diffstat (limited to 'arch/powerpc/include/asm/checksum.h')
-rw-r--r-- | arch/powerpc/include/asm/checksum.h | 79 |
1 files changed, 56 insertions, 23 deletions
diff --git a/arch/powerpc/include/asm/checksum.h b/arch/powerpc/include/asm/checksum.h index 74cd8d82628a..ee655ed1ff1b 100644 --- a/arch/powerpc/include/asm/checksum.h +++ b/arch/powerpc/include/asm/checksum.h @@ -13,20 +13,6 @@ #include <asm-generic/checksum.h> #else /* - * computes the checksum of a memory block at buff, length len, - * and adds in "sum" (32-bit) - * - * returns a 32-bit number suitable for feeding into itself - * or csum_tcpudp_magic - * - * this function must be called with even lengths, except - * for the last fragment, which may be odd - * - * it's best to have buff aligned on a 32-bit boundary - */ -extern __wsum csum_partial(const void *buff, int len, __wsum sum); - -/* * Computes the checksum of a memory block at src, length len, * and adds in "sum" (32-bit), while copying the block to dst. * If an access exception occurs on src or dst, it stores -EFAULT @@ -67,15 +53,6 @@ static inline __sum16 csum_fold(__wsum sum) return (__force __sum16)(~((__force u32)sum + tmp) >> 16); } -/* - * this routine is used for miscellaneous IP-like checksums, mainly - * in icmp.c - */ -static inline __sum16 ip_compute_csum(const void *buff, int len) -{ - return csum_fold(csum_partial(buff, len, 0)); -} - static inline __wsum csum_tcpudp_nofold(__be32 saddr, __be32 daddr, unsigned short len, unsigned short proto, @@ -174,6 +151,62 @@ static inline __sum16 ip_fast_csum(const void *iph, unsigned int ihl) return csum_fold(ip_fast_csum_nofold(iph, ihl)); } +/* + * computes the checksum of a memory block at buff, length len, + * and adds in "sum" (32-bit) + * + * returns a 32-bit number suitable for feeding into itself + * or csum_tcpudp_magic + * + * this function must be called with even lengths, except + * for the last fragment, which may be odd + * + * it's best to have buff aligned on a 32-bit boundary + */ +__wsum __csum_partial(const void *buff, int len, __wsum sum); + +static inline __wsum csum_partial(const void *buff, int len, __wsum sum) +{ + if (__builtin_constant_p(len) && len <= 16 && (len & 1) == 0) { + if (len == 2) + sum = csum_add(sum, (__force __wsum)*(const u16 *)buff); + if (len >= 4) + sum = csum_add(sum, (__force __wsum)*(const u32 *)buff); + if (len == 6) + sum = csum_add(sum, (__force __wsum) + *(const u16 *)(buff + 4)); + if (len >= 8) + sum = csum_add(sum, (__force __wsum) + *(const u32 *)(buff + 4)); + if (len == 10) + sum = csum_add(sum, (__force __wsum) + *(const u16 *)(buff + 8)); + if (len >= 12) + sum = csum_add(sum, (__force __wsum) + *(const u32 *)(buff + 8)); + if (len == 14) + sum = csum_add(sum, (__force __wsum) + *(const u16 *)(buff + 12)); + if (len >= 16) + sum = csum_add(sum, (__force __wsum) + *(const u32 *)(buff + 12)); + } else if (__builtin_constant_p(len) && (len & 3) == 0) { + sum = csum_add(sum, ip_fast_csum_nofold(buff, len >> 2)); + } else { + sum = __csum_partial(buff, len, sum); + } + return sum; +} + +/* + * this routine is used for miscellaneous IP-like checksums, mainly + * in icmp.c + */ +static inline __sum16 ip_compute_csum(const void *buff, int len) +{ + return csum_fold(csum_partial(buff, len, 0)); +} + #endif #endif /* __KERNEL__ */ #endif |