Re: [PATCH] jhash: Deinline jhash, jhash2 and __jhash_nwords
On 07/16/15 at 02:15pm, Denys Vlasenko wrote: > On 07/16/2015 12:41 PM, Thomas Graf wrote: > > On 07/16/15 at 12:02pm, Denys Vlasenko wrote: > >> +/* jhash - hash an arbitrary key > >> + * @k: sequence of bytes as key > >> + * @length: the length of the key > >> + * @initval: the previous hash, or an arbitray value > >> + * > >> + * The generic version, hashes an arbitrary sequence of bytes. > >> + * No alignment or length assumptions are made about the input key. > >> + * > >> + * Returns the hash value of the key. The result depends on endianness. > >> + */ > >> +u32 jhash(const void *key, u32 length, u32 initval) > > > > Shouldn't these live in lib/jhash.c or something? Otherwise > > everyone needs to depend on CONFIG_RHASHTABLE > > There is no CONFIG_RHASHTABLE, rhashtable.c is compiled unconditionally. > > I will send an alternative patch, which creates jhash.c; > apply whichever version you like most. Right. I misread the CONFIG_TEST_RHASHTABLE. I'm fine with this then but agree with Daniel that this must be severely tested for performance regressions. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] jhash: Deinline jhash, jhash2 and __jhash_nwords
On 07/16/2015 02:15 PM, Denys Vlasenko wrote: On 07/16/2015 12:41 PM, Thomas Graf wrote: On 07/16/15 at 12:02pm, Denys Vlasenko wrote: +/* jhash - hash an arbitrary key + * @k: sequence of bytes as key + * @length: the length of the key + * @initval: the previous hash, or an arbitray value + * + * The generic version, hashes an arbitrary sequence of bytes. + * No alignment or length assumptions are made about the input key. + * + * Returns the hash value of the key. The result depends on endianness. + */ +u32 jhash(const void *key, u32 length, u32 initval) Shouldn't these live in lib/jhash.c or something? Otherwise everyone needs to depend on CONFIG_RHASHTABLE There is no CONFIG_RHASHTABLE, rhashtable.c is compiled unconditionally. I will send an alternative patch, which creates jhash.c; apply whichever version you like most. Please also Cc netdev as networking subsys is one of the main users of jhash in various critical paths. Did you run e.g. some *_RR work load benchmarks as well to make sure there's no regression? -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] jhash: Deinline jhash, jhash2 and __jhash_nwords
On 07/16/2015 12:41 PM, Thomas Graf wrote: > On 07/16/15 at 12:02pm, Denys Vlasenko wrote: >> +/* jhash - hash an arbitrary key >> + * @k: sequence of bytes as key >> + * @length: the length of the key >> + * @initval: the previous hash, or an arbitray value >> + * >> + * The generic version, hashes an arbitrary sequence of bytes. >> + * No alignment or length assumptions are made about the input key. >> + * >> + * Returns the hash value of the key. The result depends on endianness. >> + */ >> +u32 jhash(const void *key, u32 length, u32 initval) > > Shouldn't these live in lib/jhash.c or something? Otherwise > everyone needs to depend on CONFIG_RHASHTABLE There is no CONFIG_RHASHTABLE, rhashtable.c is compiled unconditionally. I will send an alternative patch, which creates jhash.c; apply whichever version you like most. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
Re: [PATCH] jhash: Deinline jhash, jhash2 and __jhash_nwords
On 07/16/15 at 12:02pm, Denys Vlasenko wrote: > +/* jhash - hash an arbitrary key > + * @k: sequence of bytes as key > + * @length: the length of the key > + * @initval: the previous hash, or an arbitray value > + * > + * The generic version, hashes an arbitrary sequence of bytes. > + * No alignment or length assumptions are made about the input key. > + * > + * Returns the hash value of the key. The result depends on endianness. > + */ > +u32 jhash(const void *key, u32 length, u32 initval) Shouldn't these live in lib/jhash.c or something? Otherwise everyone needs to depend on CONFIG_RHASHTABLE -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
[PATCH] jhash: Deinline jhash, jhash2 and __jhash_nwords
This patch deinlines jhash, jhash2 and __jhash_nwords.
It also removes rhashtable_jhash2(key, length, seed)
because it was merely calling jhash2(key, length, seed).
With this .config: http://busybox.net/~vda/kernel_config,
after deinlining these functions have sizes and callsite counts
as follows:
__jhash_nwords: 72 bytes, 75 calls
jhash: 297 bytes, 111 calls
jhash2: 205 bytes, 136 calls
Total size decrease is about 38,000 bytes:
text data bss dec hex filename
90663567 17221960 36659200 144544727 89d93d7 vmlinux5
90625577 17221864 36659200 144506641 89cff11 vmlinux.after
Signed-off-by: Denys Vlasenko
CC: Thomas Graf
CC: Alexander Duyck
CC: Jozsef Kadlecsik
CC: Herbert Xu
CC: linux-kernel@vger.kernel.org
---
include/linux/jhash.h | 123 ++--
lib/rhashtable.c | 140 +++---
2 files changed, 137 insertions(+), 126 deletions(-)
diff --git a/include/linux/jhash.h b/include/linux/jhash.h
index 348c6f4..0b3f55d 100644
--- a/include/linux/jhash.h
+++ b/include/linux/jhash.h
@@ -31,131 +31,14 @@
/* Mask the hash value, i.e (value & jhash_mask(n)) instead of (value % n) */
#define jhash_mask(n) (jhash_size(n)-1)
-/* __jhash_mix -- mix 3 32-bit values reversibly. */
-#define __jhash_mix(a, b, c) \
-{ \
- a -= c; a ^= rol32(c, 4); c += b; \
- b -= a; b ^= rol32(a, 6); a += c; \
- c -= b; c ^= rol32(b, 8); b += a; \
- a -= c; a ^= rol32(c, 16); c += b; \
- b -= a; b ^= rol32(a, 19); a += c; \
- c -= b; c ^= rol32(b, 4); b += a; \
-}
-
-/* __jhash_final - final mixing of 3 32-bit values (a,b,c) into c */
-#define __jhash_final(a, b, c) \
-{ \
- c ^= b; c -= rol32(b, 14); \
- a ^= c; a -= rol32(c, 11); \
- b ^= a; b -= rol32(a, 25); \
- c ^= b; c -= rol32(b, 16); \
- a ^= c; a -= rol32(c, 4); \
- b ^= a; b -= rol32(a, 14); \
- c ^= b; c -= rol32(b, 24); \
-}
-
/* An arbitrary initial parameter */
#define JHASH_INITVAL 0xdeadbeef
-/* jhash - hash an arbitrary key
- * @k: sequence of bytes as key
- * @length: the length of the key
- * @initval: the previous hash, or an arbitray value
- *
- * The generic version, hashes an arbitrary sequence of bytes.
- * No alignment or length assumptions are made about the input key.
- *
- * Returns the hash value of the key. The result depends on endianness.
- */
-static inline u32 jhash(const void *key, u32 length, u32 initval)
-{
- u32 a, b, c;
- const u8 *k = key;
-
- /* Set up the internal state */
- a = b = c = JHASH_INITVAL + length + initval;
-
- /* All but the last block: affect some 32 bits of (a,b,c) */
- while (length > 12) {
- a += __get_unaligned_cpu32(k);
- b += __get_unaligned_cpu32(k + 4);
- c += __get_unaligned_cpu32(k + 8);
- __jhash_mix(a, b, c);
- length -= 12;
- k += 12;
- }
- /* Last block: affect all 32 bits of (c) */
- /* All the case statements fall through */
- switch (length) {
- case 12: c += (u32)k[11]<<24;
- case 11: c += (u32)k[10]<<16;
- case 10: c += (u32)k[9]<<8;
- case 9: c += k[8];
- case 8: b += (u32)k[7]<<24;
- case 7: b += (u32)k[6]<<16;
- case 6: b += (u32)k[5]<<8;
- case 5: b += k[4];
- case 4: a += (u32)k[3]<<24;
- case 3: a += (u32)k[2]<<16;
- case 2: a += (u32)k[1]<<8;
- case 1: a += k[0];
-__jhash_final(a, b, c);
- case 0: /* Nothing left to add */
- break;
- }
-
- return c;
-}
-
-/* jhash2 - hash an array of u32's
- * @k: the key which must be an array of u32's
- * @length: the number of u32's in the key
- * @initval: the previous hash, or an arbitray value
- *
- * Returns the hash value of the key.
- */
-static inline u32 jhash2(const u32 *k, u32 length, u32 initval)
-{
- u32 a, b, c;
-
- /* Set up the internal state */
- a = b = c = JHASH_INITVAL + (length<<2) + initval;
-
- /* Handle most of the key */
- while (length > 3) {
- a += k[0];
- b += k[1];
- c += k[2];
- __jhash_mix(a, b, c);
- length -= 3;
- k += 3;
- }
-
- /* Handle the last 3 u32's: all the case statements fall through */
- switch (length) {
- case 3: c += k[2];
- case 2: b += k[1];
- case 1: a += k[0];
- __jhash_final(a, b, c);
- case 0: /* Nothing left to add */
- break;
- }
-
- return c;
-}
-
+u32 jhash(const void *key, u32 length, u32 initval);
+u32
