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Faster q3_0 implementation, using two planes (#1)
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@pubby
pubby authored Apr 17, 2023
1 parent 80047a3 commit de542b3
Showing 1 changed file with 102 additions and 112 deletions.
214 changes: 102 additions & 112 deletions ggml.c
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Original file line number Diff line number Diff line change
Expand Up @@ -606,12 +606,12 @@ typedef struct {
static_assert(sizeof(block_q2_0) == sizeof(ggml_fp16_t) + QK2_0 / 4, "wrong q2_0 size/padding");

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

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

uint64_t qs = 0;
uint32_t lo = 0;
uint16_t hi = 0;

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

y[i].qs = qs;
y[i].d = GGML_FP32_TO_FP16(d); // overwrite unused part of uint64_t qs
y[i].d = GGML_FP32_TO_FP16(d);
y[i].qlo = lo;
y[i].qhi = hi;
}
}

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

for (int i = 0; i < nb; i++) {
const float d = GGML_FP16_TO_FP32(x[i].d);
uint64_t qs = x[i].qs;
uint_fast32_t lo = x[i].qlo;
uint_fast32_t hi = x[i].qhi << 2;
for (int l = 0; l < QK3_0; l++) {
const int8_t vi = qs & 7;
const int8_t vi = (lo & 3) | (hi & 4);
const float v = (vi - 4)*d;
y[i*QK3_0 + l] = v;
assert(!isnan(y[i*QK3_0 + l]));
qs >>= 3;
lo >>= 2;
hi >>= 1;
}
}
}
Expand Down Expand Up @@ -2193,6 +2198,39 @@ inline static void ggml_vec_dot_f16(const int n, float * restrict s, ggml_fp16_t
*s = sumf;
}

#if __AVX2__ || __AVX512F__
// Computes the dot product of signed 8-bit integers packed into 256-bit vectors,
// converting the result to 32-bit floats packed into a 256-bit vector.
static inline __m256 dotMul(__m256i bx, __m256i by) {
# if __AVXVNNIINT8__
// Perform multiplication and sum to 32-bit values
const __m256i i32 = _mm256_dpbssd_epi32(bx, by, _mm256_setzero_si256());
# else
// Get absolute values of x vectors
const __m256i ax = _mm256_sign_epi8(bx, bx);
// Sign the values of the y vectors
const __m256i sy = _mm256_sign_epi8(by, bx);
// Perform multiplication and create 16-bit values
const __m256i dot = _mm256_maddubs_epi16(ax, sy);

// Convert int16_t to int32_t by adding pairwise
const __m256i ones = _mm256_set1_epi16(1);
const __m256i i32 = _mm256_madd_epi16(ones, dot);
# endif
// Convert int32_t to float
return _mm256_cvtepi32_ps(i32);
}

// Return horizontal sum of 32-bit floats packed into a 256-bit vector.
static inline float horizontalSum(__m256 acc) {
__m128 res = _mm256_extractf128_ps(acc, 1);
res = _mm_add_ps(res, _mm256_castps256_ps128(acc));
res = _mm_add_ps(res, _mm_movehl_ps(res, res));
res = _mm_add_ss(res, _mm_movehdup_ps(res));
return _mm_cvtss_f32(res);
}
#endif

static void ggml_vec_dot_q2_0_q8_0(const int n, float * restrict s, const void * restrict vx, const void * restrict vy) {
assert(n % QK2_0 == 0);
const int nb = n / QK2_0;
Expand Down Expand Up @@ -2222,30 +2260,15 @@ static void ggml_vec_dot_q2_0_q8_0(const int n, float * restrict s, const void *
// Load y vector
const __m256i by = _mm256_loadu_si256((const __m256i *)y[i].qs);

// Get absolute values of x vectors
const __m256i ax = _mm256_sign_epi8(bx, bx);
// Sign the values of the y vectors
const __m256i sy = _mm256_sign_epi8(by, bx);
// Perform multiplication and create 16-bit values
const __m256i dot = _mm256_maddubs_epi16(ax, sy);

// Convert int16_t to int32_t by adding pairwise
const __m256i ones = _mm256_set1_epi16(1);
__m256i i32 = _mm256_madd_epi16(ones, dot);

// Convert int32_t to float
__m256 p = _mm256_cvtepi32_ps(i32);
// Do the product:
__m256 p = dotMul(bx, by);

// Apply the scale, and accumulate
acc = _mm256_fmadd_ps(scale, p, acc);
}

// Return horizontal sum of the acc vector
__m128 res = _mm256_extractf128_ps(acc, 1);
res = _mm_add_ps(res, _mm256_castps256_ps128(acc));
res = _mm_add_ps(res, _mm_movehl_ps(res, res));
res = _mm_add_ss(res, _mm_movehdup_ps(res));
sumf = _mm_cvtss_f32(res);
sumf = horizontalSum(acc);
#else
for (int i = 0; i < nb; i++) {
const float d0 = GGML_FP16_TO_FP32(x[i].d);
Expand All @@ -2270,6 +2293,20 @@ static void ggml_vec_dot_q2_0_q8_0(const int n, float * restrict s, const void *
*s = sumf;
}

// Lookup table used to convert q3_0 to SIMD vectors.
// Expands the bits of an 8-bit value into a 64 bit result, turning each bit into a byte.
// A zero bit turns into 0xFC, while a one bit turns into 0x00.
#define B0(n) 0x ## n
#define B1(n) B0(n ## FC), B0(n ## 00)
#define B2(n) B1(n ## FC), B1(n ## 00)
#define B3(n) B2(n ## FC), B2(n ## 00)
#define B4(n) B3(n ## FC), B3(n ## 00)
#define B5(n) B4(n ## FC), B4(n ## 00)
#define B6(n) B5(n ## FC), B5(n ## 00)
#define B7(n) B6(n ## FC), B6(n ## 00)
#define B8( ) B7( FC), B7( 00)
static const uint64_t ggml_q3_table[256] = { B8() };

static void ggml_vec_dot_q3_0_q8_0(const int n, float * restrict s, const void * restrict vx, const void * restrict vy) {
assert(n % QK3_0 == 0);
const int nb = n / QK3_0;
Expand All @@ -2282,103 +2319,54 @@ static void ggml_vec_dot_q3_0_q8_0(const int n, float * restrict s, const void *

#if defined(__AVX2__)
// Initialize accumulator with zeros
__m128 acc = _mm_setzero_ps();
__m256 acc = _mm256_setzero_ps();

for (int i = 0; i < nb/2; i++) {
const __m128 scale_y = _mm_set1_ps(y[i].d);
for (int u = 0; u < 2; u++) { // let the compiler unroll this
// Compute combined scale for the block
const __m128 scale_x = _mm_set1_ps(GGML_FP16_TO_FP32(x[i*2+u].d));
const __m128 scale = _mm_mul_ps(scale_x, scale_y);

__m256i bxx = _mm256_set1_epi64x(x[i*2+u].qs);

// legend: _=zero +=one .=don't care 0-f=3bit quantized values s=fp16 scale

// shift the copies to be able to reach all values
// 255 192 128 64 0
// | | | |
// sssssfedcba9876543210sssssfedcba9876543210sssssfedcba9876543210sssssfedcba9876543210 in
// sssfedcba9876543210_______________________sfedcba9876543210____sssssfedcba9876543210 shift left
// _______________________sssssfedcba98765432__________________________________________ shift right
// sssfedcba9876543210____sssssfedcba98765432sfedcba9876543210____sssssfedcba9876543210 out
// ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^ ^
// e b 6 3 _ . f a 7 2 c 9 4 1 _ . d 8 5 0
const __m256i shift_l = _mm256_set_epi64x(2*3, 64, 4*3, 0);
const __m256i shift_r = _mm256_set_epi64x( 64, 2*3, 64, 64);
bxx = _mm256_or_si256(_mm256_sllv_epi64(bxx, shift_l), _mm256_srlv_epi64(bxx, shift_r));

// add to itself in masked places to shift some values left one bit
// 127 64 0
// | | | | | | | | | | | | | | | |
// ssssfffeeedddcccbbbaaa999888777666555444333222111000____________ssssssssssssssssfffeeedddcccbbbaaa999888777666555444333222111000 in
// _____________________++++____________________++++____________________________________++++____________________++++_______________ mask
// _____________________.999____________________.111____________________________________.ddd____________________.555_______________ masked
// .............ccc.....999.............444.....111....____________.....................ddd.............888.....555.............000 sum
//
// 255 192 128
// | | | | | | | | | | | | | | | |
// ssssssssssfffeeedddcccbbbaaa999888777666555444333222111000____________ssssssssssssssssfffeeedddcccbbbaaa999888777666555444333222 in
// _____________________++++____________________++++____________________________________++++____________________++++_______________ mask
// _____________________.bbb____________________.333____________________________________.fff____________________.777_______________ masked
// .............eee.....bbb.............666.....333..........____________...............fff.............aaa.....777.............222 sum
const __m256i doublemask = _mm256_set1_epi64x(0x078000078000);
bxx = _mm256_add_epi64(bxx, _mm256_and_si256(doublemask, bxx));

// collect 16 bytes from 256 into 128 bits
const __m256i shufmask = _mm256_set_epi8(
5,14,-1,-1,13, 3,-1,-1, 2,11,-1,-1,10, 0,-1,-1,
-1,-1, 5,14,-1,-1,13, 3,-1,-1, 2,11,-1,-1,10, 0);
bxx = _mm256_shuffle_epi8(bxx, shufmask);

__m128i bx = _mm_or_si128(_mm256_castsi256_si128(bxx), _mm256_extracti128_si256(bxx, 1));

const __m128i mask = _mm_set1_epi8(7);
bx = _mm_and_si128(mask, bx);

const __m128i off = _mm_set1_epi8(4);
bx = _mm_sub_epi8(bx, off);

const __m128i by = _mm_loadu_si128((const __m128i *)(y[i].qs + u*QK3_0));
__m256i bx = bytesFromCrumbs(x[i*2+1].qlo, x[i*2].qlo);

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

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

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

// Apply the scale, and accumulate
acc = _mm_fmadd_ps(scale, p, acc);
}
// Load y vector
const __m256i by = _mm256_loadu_si256((const __m256i *)y[i].qs);

// Do the product,
__m256 p = dotMul(bx, by);

// Apply the scale, and accumulate
acc = _mm256_fmadd_ps(scale, p, acc);
}

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

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

int sumi = 0;
for (int j = 0; j < QK3_0; j++) {
const int8_t i0 = (int8_t)(qs0 & 7) - 4;
const int_fast16_t i1 = p1[j];
for (int l = 0; l < QK3_0; l++) {
const int8_t i0 = (int8_t)((lo0 & 3) | ((hi0 & 4) - 4));
const int_fast16_t i1 = p1[l];

sumi += i0 * i1;

qs0 >>= 3;
lo0 >>= 2;
hi0 >>= 1;
}
sumf += d0 * d1 * sumi;
}
Expand Down Expand Up @@ -11630,11 +11618,13 @@ size_t ggml_quantize_q3_0(const float * src, void * dst, int n, int k, int64_t h
quantize_row_q3_0(src + j, y, k);

for (int i = 0; i < nb; i++) {
uint64_t qs = y[i].qs;
uint_fast32_t lo = y[i].qlo;
uint_fast32_t hi = y[i].qhi << 2;
for (int l = 0; l < QK3_0; l++) {
const int8_t vi = qs & 7;
int8_t vi = (lo & 3) | (hi & 4);
hist[vi]++;
qs >>= 3;
lo >>= 2;
hi >>= 1;
}
}
}
Expand Down

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