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Faster q3_0 implementation, using two planes (#1)
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‎ggml.c

Lines changed: 102 additions & 112 deletions
Original file line numberDiff line numberDiff line change
@@ -606,12 +606,12 @@ typedef struct {
606606
static_assert(sizeof(block_q2_0) == sizeof(ggml_fp16_t) + QK2_0 / 4, "wrong q2_0 size/padding");
607607

608608
#define QK3_0 16
609-
typedef union {
610-
struct {
611-
uint16_t pad[3];
612-
ggml_fp16_t d;
613-
};
614-
uint64_t qs;
609+
typedef struct {
610+
ggml_fp16_t d;
611+
// Instead of representing q3_0 as a packed format "...210210210210",
612+
// represent it as two planes: "...10101010" and "...2222"
613+
uint16_t qhi; // The highest bit of each 3-bit number, packed together
614+
uint32_t qlo; // The low 2-bits of each 3-bit number, packed together
615615
} block_q3_0;
616616
static_assert(sizeof(block_q3_0) == sizeof(ggml_fp16_t) + QK3_0 * 3 / 8, "wrong q3_0 size/padding");
617617

@@ -691,17 +691,20 @@ static void quantize_row_q3_0(const float * restrict x, block_q3_0 * restrict y,
691691
const float d = max / -4;
692692
const float id = d ? 1.0f/d : 0.0f;
693693

694-
uint64_t qs = 0;
694+
uint32_t lo = 0;
695+
uint16_t hi = 0;
695696

696697
for (int l = 0; l < QK3_0; l++) {
697698
const float v = x[i*QK3_0 + l]*id;
698699
const uint8_t vi = MIN(7, (int8_t)roundf(v) + 4);
699700
assert(vi < 8);
700-
qs |= (uint64_t)vi << (l*3);
701+
lo |= (vi & 3) << (l * 2);
702+
hi |= ((vi >> 2) & 1) << l;
701703
}
702704

703-
y[i].qs = qs;
704-
y[i].d = GGML_FP32_TO_FP16(d); // overwrite unused part of uint64_t qs
705+
y[i].d = GGML_FP32_TO_FP16(d);
706+
y[i].qlo = lo;
707+
y[i].qhi = hi;
705708
}
706709
}
707710

@@ -1335,13 +1338,15 @@ static void dequantize_row_q3_0(const void * restrict vx, float * restrict y, in
13351338

13361339
for (int i = 0; i < nb; i++) {
13371340
const float d = GGML_FP16_TO_FP32(x[i].d);
1338-
uint64_t qs = x[i].qs;
1341+
uint_fast32_t lo = x[i].qlo;
1342+
uint_fast32_t hi = x[i].qhi << 2;
13391343
for (int l = 0; l < QK3_0; l++) {
1340-
const int8_t vi = qs & 7;
1344+
const int8_t vi = (lo & 3) | (hi & 4);
13411345
const float v = (vi - 4)*d;
13421346
y[i*QK3_0 + l] = v;
13431347
assert(!isnan(y[i*QK3_0 + l]));
1344-
qs >>= 3;
1348+
lo >>= 2;
1349+
hi >>= 1;
13451350
}
13461351
}
13471352
}
@@ -2193,6 +2198,39 @@ inline static void ggml_vec_dot_f16(const int n, float * restrict s, ggml_fp16_t
21932198
*s = sumf;
21942199
}
21952200

2201+
#if __AVX2__ || __AVX512F__
2202+
// Computes the dot product of signed 8-bit integers packed into 256-bit vectors,
2203+
// converting the result to 32-bit floats packed into a 256-bit vector.
2204+
static inline __m256 dotMul(__m256i bx, __m256i by) {
2205+
# if __AVXVNNIINT8__
2206+
// Perform multiplication and sum to 32-bit values
2207+
const __m256i i32 = _mm256_dpbssd_epi32(bx, by, _mm256_setzero_si256());
2208+
# else
2209+
// Get absolute values of x vectors
2210+
const __m256i ax = _mm256_sign_epi8(bx, bx);
2211+
// Sign the values of the y vectors
2212+
const __m256i sy = _mm256_sign_epi8(by, bx);
2213+
// Perform multiplication and create 16-bit values
2214+
const __m256i dot = _mm256_maddubs_epi16(ax, sy);
2215+
2216+
// Convert int16_t to int32_t by adding pairwise
2217+
const __m256i ones = _mm256_set1_epi16(1);
2218+
const __m256i i32 = _mm256_madd_epi16(ones, dot);
2219+
# endif
2220+
// Convert int32_t to float
2221+
return _mm256_cvtepi32_ps(i32);
2222+
}
2223+
2224+
// Return horizontal sum of 32-bit floats packed into a 256-bit vector.
2225+
static inline float horizontalSum(__m256 acc) {
2226+
__m128 res = _mm256_extractf128_ps(acc, 1);
2227+
res = _mm_add_ps(res, _mm256_castps256_ps128(acc));
2228+
res = _mm_add_ps(res, _mm_movehl_ps(res, res));
2229+
res = _mm_add_ss(res, _mm_movehdup_ps(res));
2230+
return _mm_cvtss_f32(res);
2231+
}
2232+
#endif
2233+
21962234
static void ggml_vec_dot_q2_0_q8_0(const int n, float * restrict s, const void * restrict vx, const void * restrict vy) {
21972235
assert(n % QK2_0 == 0);
21982236
const int nb = n / QK2_0;
@@ -2222,30 +2260,15 @@ static void ggml_vec_dot_q2_0_q8_0(const int n, float * restrict s, const void *
22222260
// Load y vector
22232261
const __m256i by = _mm256_loadu_si256((const __m256i *)y[i].qs);
22242262

2225-
// Get absolute values of x vectors
2226-
const __m256i ax = _mm256_sign_epi8(bx, bx);
2227-
// Sign the values of the y vectors
2228-
const __m256i sy = _mm256_sign_epi8(by, bx);
2229-
// Perform multiplication and create 16-bit values
2230-
const __m256i dot = _mm256_maddubs_epi16(ax, sy);
2231-
2232-
// Convert int16_t to int32_t by adding pairwise
2233-
const __m256i ones = _mm256_set1_epi16(1);
2234-
__m256i i32 = _mm256_madd_epi16(ones, dot);
2235-
2236-
// Convert int32_t to float
2237-
__m256 p = _mm256_cvtepi32_ps(i32);
2263+
// Do the product:
2264+
__m256 p = dotMul(bx, by);
22382265

22392266
// Apply the scale, and accumulate
22402267
acc = _mm256_fmadd_ps(scale, p, acc);
22412268
}
22422269

22432270
// Return horizontal sum of the acc vector
2244-
__m128 res = _mm256_extractf128_ps(acc, 1);
2245-
res = _mm_add_ps(res, _mm256_castps256_ps128(acc));
2246-
res = _mm_add_ps(res, _mm_movehl_ps(res, res));
2247-
res = _mm_add_ss(res, _mm_movehdup_ps(res));
2248-
sumf = _mm_cvtss_f32(res);
2271+
sumf = horizontalSum(acc);
22492272
#else
22502273
for (int i = 0; i < nb; i++) {
22512274
const float d0 = GGML_FP16_TO_FP32(x[i].d);
@@ -2270,6 +2293,20 @@ static void ggml_vec_dot_q2_0_q8_0(const int n, float * restrict s, const void *
22702293
*s = sumf;
22712294
}
22722295

2296+
// Lookup table used to convert q3_0 to SIMD vectors.
2297+
// Expands the bits of an 8-bit value into a 64 bit result, turning each bit into a byte.
2298+
// A zero bit turns into 0xFC, while a one bit turns into 0x00.
2299+
#define B0(n) 0x ## n
2300+
#define B1(n) B0(n ## FC), B0(n ## 00)
2301+
#define B2(n) B1(n ## FC), B1(n ## 00)
2302+
#define B3(n) B2(n ## FC), B2(n ## 00)
2303+
#define B4(n) B3(n ## FC), B3(n ## 00)
2304+
#define B5(n) B4(n ## FC), B4(n ## 00)
2305+
#define B6(n) B5(n ## FC), B5(n ## 00)
2306+
#define B7(n) B6(n ## FC), B6(n ## 00)
2307+
#define B8( ) B7( FC), B7( 00)
2308+
static const uint64_t ggml_q3_table[256] = { B8() };
2309+
22732310
static void ggml_vec_dot_q3_0_q8_0(const int n, float * restrict s, const void * restrict vx, const void * restrict vy) {
22742311
assert(n % QK3_0 == 0);
22752312
const int nb = n / QK3_0;
@@ -2282,103 +2319,54 @@ static void ggml_vec_dot_q3_0_q8_0(const int n, float * restrict s, const void *
22822319

22832320
#if defined(__AVX2__)
22842321
// Initialize accumulator with zeros
2285-
__m128 acc = _mm_setzero_ps();
2322+
__m256 acc = _mm256_setzero_ps();
2323+
22862324
for (int i = 0; i < nb/2; i++) {
2287-
const __m128 scale_y = _mm_set1_ps(y[i].d);
2288-
for (int u = 0; u < 2; u++) { // let the compiler unroll this
2289-
// Compute combined scale for the block
2290-
const __m128 scale_x = _mm_set1_ps(GGML_FP16_TO_FP32(x[i*2+u].d));
2291-
const __m128 scale = _mm_mul_ps(scale_x, scale_y);
2292-
2293-
__m256i bxx = _mm256_set1_epi64x(x[i*2+u].qs);
2294-
2295-
// legend: _=zero +=one .=don't care 0-f=3bit quantized values s=fp16 scale
2296-
2297-
// shift the copies to be able to reach all values
2298-
// 255 192 128 64 0
2299-
// | | | |
2300-
// sssssfedcba9876543210sssssfedcba9876543210sssssfedcba9876543210sssssfedcba9876543210 in
2301-
// sssfedcba9876543210_______________________sfedcba9876543210____sssssfedcba9876543210 shift left
2302-
// _______________________sssssfedcba98765432__________________________________________ shift right
2303-
// sssfedcba9876543210____sssssfedcba98765432sfedcba9876543210____sssssfedcba9876543210 out
2304-
// ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
2305-
// e b 6 3 _ . f a 7 2 c 9 4 1 _ . d 8 5 0
2306-
const __m256i shift_l = _mm256_set_epi64x(2*3, 64, 4*3, 0);
2307-
const __m256i shift_r = _mm256_set_epi64x( 64, 2*3, 64, 64);
2308-
bxx = _mm256_or_si256(_mm256_sllv_epi64(bxx, shift_l), _mm256_srlv_epi64(bxx, shift_r));
2309-
2310-
// add to itself in masked places to shift some values left one bit
2311-
// 127 64 0
2312-
// | | | | | | | | | | | | | | | |
2313-
// ssssfffeeedddcccbbbaaa999888777666555444333222111000____________ssssssssssssssssfffeeedddcccbbbaaa999888777666555444333222111000 in
2314-
// _____________________++++____________________++++____________________________________++++____________________++++_______________ mask
2315-
// _____________________.999____________________.111____________________________________.ddd____________________.555_______________ masked
2316-
// .............ccc.....999.............444.....111....____________.....................ddd.............888.....555.............000 sum
2317-
//
2318-
// 255 192 128
2319-
// | | | | | | | | | | | | | | | |
2320-
// ssssssssssfffeeedddcccbbbaaa999888777666555444333222111000____________ssssssssssssssssfffeeedddcccbbbaaa999888777666555444333222 in
2321-
// _____________________++++____________________++++____________________________________++++____________________++++_______________ mask
2322-
// _____________________.bbb____________________.333____________________________________.fff____________________.777_______________ masked
2323-
// .............eee.....bbb.............666.....333..........____________...............fff.............aaa.....777.............222 sum
2324-
const __m256i doublemask = _mm256_set1_epi64x(0x078000078000);
2325-
bxx = _mm256_add_epi64(bxx, _mm256_and_si256(doublemask, bxx));
2326-
2327-
// collect 16 bytes from 256 into 128 bits
2328-
const __m256i shufmask = _mm256_set_epi8(
2329-
5,14,-1,-1,13, 3,-1,-1, 2,11,-1,-1,10, 0,-1,-1,
2330-
-1,-1, 5,14,-1,-1,13, 3,-1,-1, 2,11,-1,-1,10, 0);
2331-
bxx = _mm256_shuffle_epi8(bxx, shufmask);
2332-
2333-
__m128i bx = _mm_or_si128(_mm256_castsi256_si128(bxx), _mm256_extracti128_si256(bxx, 1));
2334-
2335-
const __m128i mask = _mm_set1_epi8(7);
2336-
bx = _mm_and_si128(mask, bx);
2337-
2338-
const __m128i off = _mm_set1_epi8(4);
2339-
bx = _mm_sub_epi8(bx, off);
2340-
2341-
const __m128i by = _mm_loadu_si128((const __m128i *)(y[i].qs + u*QK3_0));
2325+
__m256i bx = bytesFromCrumbs(x[i*2+1].qlo, x[i*2].qlo);
23422326

2343-
// Get absolute values of x vectors
2344-
const __m128i ax = _mm_sign_epi8(bx, bx);
2345-
// Sign the values of the y vectors
2346-
const __m128i sy = _mm_sign_epi8(by, bx);
2347-
// Perform multiplication and create 16-bit values
2348-
const __m128i dot = _mm_maddubs_epi16(ax, sy);
2327+
__m256i const bxhi = _mm256_set_epi64x(
2328+
ggml_q3_table[x[i*2+1].qhi >> 8], ggml_q3_table[x[i*2+1].qhi & 0xFF],
2329+
ggml_q3_table[x[i*2+0].qhi >> 8], ggml_q3_table[x[i*2+0].qhi & 0xFF]);
23492330

2350-
// Convert int16_t to int32_t by adding pairwise
2351-
const __m128i ones = _mm_set1_epi16(1);
2352-
__m128i i32 = _mm_madd_epi16(dot, ones);
2331+
// OR the high bits (which also handles the sign):
2332+
bx = _mm256_or_si256(bx, bxhi);
23532333

2354-
// Convert int32_t to float
2355-
const __m128 p = _mm_cvtepi32_ps(i32);
2334+
// Compute combined scale for the block
2335+
const __m128 scale_lo = _mm_set1_ps(GGML_FP16_TO_FP32(x[i*2+0].d));
2336+
const __m128 scale_hi = _mm_set1_ps(GGML_FP16_TO_FP32(x[i*2+1].d));
2337+
__m256 scale = _mm256_set_m128(scale_hi, scale_lo);
2338+
scale = _mm256_mul_ps(scale, _mm256_broadcast_ss(&y[i].d));
23562339

2357-
// Apply the scale, and accumulate
2358-
acc = _mm_fmadd_ps(scale, p, acc);
2359-
}
2340+
// Load y vector
2341+
const __m256i by = _mm256_loadu_si256((const __m256i *)y[i].qs);
2342+
2343+
// Do the product,
2344+
__m256 p = dotMul(bx, by);
2345+
2346+
// Apply the scale, and accumulate
2347+
acc = _mm256_fmadd_ps(scale, p, acc);
23602348
}
23612349

23622350
// Return horizontal sum of the acc vector
2363-
__m128 res = _mm_add_ps(acc, _mm_movehl_ps(acc, acc));
2364-
res = _mm_add_ss(res, _mm_movehdup_ps(res));
2365-
sumf = _mm_cvtss_f32(res);
2351+
sumf = horizontalSum(acc);
23662352
#else
23672353
for (int i = 0; i < nb; i++) {
23682354
const float d0 = GGML_FP16_TO_FP32(x[i].d);
23692355
const float d1 = y[i/2].d;
23702356

2371-
uint64_t qs0 = x[i].qs;
2357+
uint_fast32_t lo0 = x[i].qlo;
2358+
uint_fast32_t hi0 = x[i].qhi << 2;
23722359
const int8_t * restrict p1 = y[i/2].qs + (i%2)*QK3_0;
23732360

23742361
int sumi = 0;
2375-
for (int j = 0; j < QK3_0; j++) {
2376-
const int8_t i0 = (int8_t)(qs0 & 7) - 4;
2377-
const int_fast16_t i1 = p1[j];
2362+
for (int l = 0; l < QK3_0; l++) {
2363+
const int8_t i0 = (int8_t)((lo0 & 3) | ((hi0 & 4) - 4));
2364+
const int_fast16_t i1 = p1[l];
23782365

23792366
sumi += i0 * i1;
23802367

2381-
qs0 >>= 3;
2368+
lo0 >>= 2;
2369+
hi0 >>= 1;
23822370
}
23832371
sumf += d0 * d1 * sumi;
23842372
}
@@ -11630,11 +11618,13 @@ size_t ggml_quantize_q3_0(const float * src, void * dst, int n, int k, int64_t h
1163011618
quantize_row_q3_0(src + j, y, k);
1163111619

1163211620
for (int i = 0; i < nb; i++) {
11633-
uint64_t qs = y[i].qs;
11621+
uint_fast32_t lo = y[i].qlo;
11622+
uint_fast32_t hi = y[i].qhi << 2;
1163411623
for (int l = 0; l < QK3_0; l++) {
11635-
const int8_t vi = qs & 7;
11624+
int8_t vi = (lo & 3) | (hi & 4);
1163611625
hist[vi]++;
11637-
qs >>= 3;
11626+
lo >>= 2;
11627+
hi >>= 1;
1163811628
}
1163911629
}
1164011630
}

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