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Slight quantization improvement for Q4_K and Q5_K (#5361)
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* Q4_K: slightly better quantization

* Q5_K: slightly better quantization

---------

Co-authored-by: Iwan Kawrakow <iwan.kawrakow@gmail.com>
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@ikawrakow @Kawrakow
ikawrakow and Kawrakow authored Feb 6, 2024
1 parent 2e9c0bd commit f57fadc
Showing 1 changed file with 33 additions and 42 deletions.
75 changes: 33 additions & 42 deletions ggml-quants.c
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Original file line number Diff line number Diff line change
Expand Up @@ -2381,45 +2381,38 @@ static void quantize_row_q4_K_impl(const float * restrict x, block_q4_K * restri

uint8_t L[QK_K];
uint8_t Laux[32];
uint8_t Ls[QK_K/32];
uint8_t Lm[QK_K/32];
float weights[32];
float mins[QK_K/32];
float scales[QK_K/32];
float sw[QK_K/32];
float mins[QK_K/32];
float scales[QK_K/32];

for (int i = 0; i < nb; i++) {

float sum_x2 = 0;
for (int l = 0; l < QK_K; ++l) sum_x2 += x[l] * x[l];
float sigma2 = sum_x2/QK_K;
float sigma2 = 2*sum_x2/QK_K;
float av_x = sqrtf(sigma2);

float max_scale = 0; // as we are deducting the min, scales are always positive
float max_min = 0;
for (int j = 0; j < QK_K/32; ++j) {
if (quant_weights) {
const float * qw = quant_weights + QK_K*i + 32*j;
for (int l = 0; l < 32; ++l) weights[l] = qw[l] * sqrtf(sigma2 + x[32*j + l]*x[32*j + l]);
} else {
for (int l = 0; l < 32; ++l) weights[l] = av_x + fabsf(x[32*j + l]);
}
float sumw = 0;
for (int l = 0; l < 32; ++l) sumw += weights[l];
sw[j] = sumw;
scales[j] = make_qkx3_quants(32, 15, x + 32*j, weights, L + 32*j, &mins[j], Laux, -0.9f, 0.05f, 36, false);
//scales[j] = make_qkx2_quants(32, 15, x + 32*j, weights, L + 32*j, &mins[j], Laux, -1.f, 0.1f, 20, false);
float scale = scales[j];
if (scale > max_scale) {
max_scale = scale;
}
float min = mins[j];
if (min > max_min) {
max_min = min;
}
}

float inv_scale = max_scale > 0 ? 63.f/max_scale : 0.f;
float inv_min = max_min > 0 ? 63.f/max_min : 0.f;
float d_block = make_qp_quants(QK_K/32, 63, scales, Ls, sw);
float m_block = make_qp_quants(QK_K/32, 63, mins, Lm, sw);
for (int j = 0; j < QK_K/32; ++j) {
uint8_t ls = nearest_int(inv_scale*scales[j]);
uint8_t lm = nearest_int(inv_min*mins[j]);
ls = MIN(63, ls);
lm = MIN(63, lm);
uint8_t ls = Ls[j];
uint8_t lm = Lm[j];
if (j < 4) {
y[i].scales[j] = ls;
y[i].scales[j+4] = lm;
Expand All @@ -2429,8 +2422,8 @@ static void quantize_row_q4_K_impl(const float * restrict x, block_q4_K * restri
y[i].scales[j-0] |= ((lm >> 4) << 6);
}
}
y[i].d = GGML_FP32_TO_FP16(max_scale/63.f);
y[i].dmin = GGML_FP32_TO_FP16(max_min/63.f);
y[i].d = GGML_FP32_TO_FP16(d_block);
y[i].dmin = GGML_FP32_TO_FP16(m_block);

uint8_t sc, m;
for (int j = 0; j < QK_K/32; ++j) {
Expand Down Expand Up @@ -2688,43 +2681,41 @@ static void quantize_row_q5_K_impl(const float * restrict x, block_q5_K * restri
const int nb = n_per_row / QK_K;

uint8_t L[QK_K];
float mins[QK_K/32];
float scales[QK_K/32];
float weights[32];
uint8_t Laux[32];
uint8_t Ls[QK_K/32];
uint8_t Lm[QK_K/32];
float mins[QK_K/32];
float scales[QK_K/32];
float sw[QK_K/32];
float weights[32];

for (int i = 0; i < nb; i++) {

float sum_x2 = 0;
for (int l = 0; l < QK_K; ++l) sum_x2 += x[l] * x[l];
float sigma2 = sum_x2/QK_K;
float sigma2 = 2*sum_x2/QK_K;
float av_x = sqrtf(sigma2);

float max_scale = 0; // as we are deducting the min, scales are always positive
float max_min = 0;
for (int j = 0; j < QK_K/32; ++j) {
if (quant_weights) {
const float * qw = quant_weights + QK_K*i + 32*j;
for (int l = 0; l < 32; ++l) weights[l] = qw[l] * sqrtf(sigma2 + x[32*j + l]*x[32*j + l]);
} else {
for (int l = 0; l < 32; ++l) weights[l] = av_x + fabsf(x[32*j + l]);
}
float sumw = 0;
for (int l = 0; l < 32; ++l) sumw += weights[l];
sw[j] = sumw;

scales[j] = make_qkx3_quants(32, 31, x + 32*j, weights, L + 32*j, &mins[j], Laux, -0.9f, 0.05f, 36, false);
float scale = scales[j];
if (scale > max_scale) {
max_scale = scale;
}
float min = mins[j];
if (min > max_min) {
max_min = min;
}
}

float inv_scale = max_scale > 0 ? 63.f/max_scale : 0.f;
float inv_min = max_min > 0 ? 63.f/max_min : 0.f;
float d_block = make_qp_quants(QK_K/32, 63, scales, Ls, sw);
float m_block = make_qp_quants(QK_K/32, 63, mins, Lm, sw);

for (int j = 0; j < QK_K/32; ++j) {
uint8_t ls = nearest_int(inv_scale*scales[j]);
uint8_t lm = nearest_int(inv_min*mins[j]);
uint8_t ls = Ls[j];
uint8_t lm = Lm[j];
ls = MIN(63, ls);
lm = MIN(63, lm);
if (j < 4) {
Expand All @@ -2736,8 +2727,8 @@ static void quantize_row_q5_K_impl(const float * restrict x, block_q5_K * restri
y[i].scales[j-0] |= ((lm >> 4) << 6);
}
}
y[i].d = GGML_FP32_TO_FP16(max_scale/63.f);
y[i].dmin = GGML_FP32_TO_FP16(max_min/63.f);
y[i].d = GGML_FP32_TO_FP16(d_block);
y[i].dmin = GGML_FP32_TO_FP16(m_block);

uint8_t sc, m;
for (int j = 0; j < QK_K/32; ++j) {
Expand Down

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