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Nexesenexikawrakow
Nexesenex
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ikawrakow
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Improved IQ2_XS quantization #312
Co-Authored-By: Kawrakow <iwankawrakow@gmail.com>
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‎ggml/src/ggml-quants.c‎

Lines changed: 93 additions & 34 deletions
Original file line numberDiff line numberDiff line change
@@ -3319,6 +3319,12 @@ static void quantize_row_iq2_xxs_impl(const float * GGML_RESTRICT x, void * GGML
33193319
}
33203320
}
33213321

3322+
static int iq1_sort_helper(const void * left, const void * right) {
3323+
const float * l = left;
3324+
const float * r = right;
3325+
return *l < *r ? -1 : *l > *r ? 1 : 0;
3326+
}
3327+
33223328
static void quantize_row_iq2_xs_impl(const float * GGML_RESTRICT x, void * GGML_RESTRICT vy, int64_t n, const float * GGML_RESTRICT quant_weights) {
33233329

33243330
const int gindex = iq2_data_index(GGML_TYPE_IQ2_XS);
@@ -3349,6 +3355,9 @@ static void quantize_row_iq2_xs_impl(const float * GGML_RESTRICT x, void * GGML_
33493355
bool is_on_grid_aux[2];
33503356
uint8_t block_signs[2];
33513357
uint16_t q2[2*(QK_K/16)];
3358+
uint16_t index[2], aux_index[2];
3359+
float sumx[17], sumw[17], pairs[32];
3360+
int * int_pairs = (int *)(pairs + 1);
33523361

33533362
for (int ibl = 0; ibl < nbl; ++ibl) {
33543363

@@ -3397,11 +3406,35 @@ static void quantize_row_iq2_xs_impl(const float * GGML_RESTRICT x, void * GGML_
33973406
memset(L, 0, 16);
33983407
continue;
33993408
}
3400-
float best = 0;
3401-
float scale = max/(2*kMaxQ-1);
3409+
for (int j = 0; j < 16; ++j) {
3410+
pairs[2*j] = xval[j];
3411+
int_pairs[2*j] = j;
3412+
}
3413+
qsort(pairs, 16, 2*sizeof(float), iq1_sort_helper);
3414+
{
3415+
sumx[0] = sumw[0] = 0;
3416+
for (int j = 0; j < 16; ++j) {
3417+
int i = int_pairs[2*j];
3418+
sumx[j+1] = sumx[j] + weight[i]*xval[i];
3419+
sumw[j+1] = sumw[j] + weight[i];
3420+
}
3421+
}
3422+
float best = 0, scale = 0;
3423+
for (int i1 = 0; i1 <= 16; ++i1) {
3424+
for (int i2 = i1; i2 <= 16; ++i2) {
3425+
float sumqx = (sumx[i1] - sumx[0])*1 + (sumx[i2] - sumx[i1])*3 + (sumx[16] - sumx[i2])*5;
3426+
float sumq2 = (sumw[i1] - sumw[0])*1 + (sumw[i2] - sumw[i1])*9 + (sumw[16] - sumw[i2])*25;
3427+
if (sumq2 > 0 && sumqx*sumqx > best*sumq2) {
3428+
scale = sumqx/sumq2; best = scale*sumqx;
3429+
}
3430+
}
3431+
}
3432+
best = 0;
3433+
float eff_max = scale*(2*kMaxQ - 1);
34023434
is_on_grid[0] = is_on_grid[1] = true;
3403-
for (int is = -9; is <= 9; ++is) {
3404-
float id = (2*kMaxQ-1+is*0.1f)/max;
3435+
index[0] = index[1] = 0;
3436+
for (int is = -7; is <= 7; ++is) {
3437+
float id = (2*kMaxQ-1+is*0.1f)/eff_max;
34053438
float this_scale = 1/id;
34063439
for (int k = 0; k < 2; ++k) {
34073440
for (int i = 0; i < 8; ++i) {
@@ -3417,6 +3450,7 @@ static void quantize_row_iq2_xs_impl(const float * GGML_RESTRICT x, void * GGML_
34173450
const uint16_t * neighbours = kneighbors_q2xs - kmap_q2xs[u] - 1;
34183451
grid_index = iq2_find_best_neighbour(neighbours, kgrid_q2xs, xval + 8*k, waux + 8*k, this_scale, Laux + 8*k);
34193452
}
3453+
aux_index[k] = grid_index;
34203454
}
34213455
float sumqx = 0, sumq2 = 0;
34223456
for (int i = 0; i < 16; ++i) {
@@ -3429,35 +3463,45 @@ static void quantize_row_iq2_xs_impl(const float * GGML_RESTRICT x, void * GGML_
34293463
scale = sumqx/sumq2; best = scale*sumqx;
34303464
for (int i = 0; i < 16; ++i) L[i] = Laux[i];
34313465
for (int k = 0; k < 2; ++k) is_on_grid[k] = is_on_grid_aux[k];
3466+
for (int k = 0; k < 2; ++k) index[k] = aux_index[k];
34323467
}
34333468
}
3434-
int n_not_ongrid = 0;
3435-
for (int k = 0; k < 2; ++k) if (!is_on_grid[k]) ++n_not_ongrid;
3436-
if (n_not_ongrid > 0 && scale > 0) {
3437-
float id = 1/scale;
3438-
for (int k = 0; k < 2; ++k) {
3439-
if (is_on_grid[k]) continue;
3440-
uint16_t u = 0;
3441-
for (int i = 0; i < 8; ++i) {
3442-
int l = nearest_int(0.5f*(id*xval[8*k+i]-1));
3443-
l = MAX(0, MIN(kMaxQ-1, l));
3444-
u |= (l << 2*i);
3445-
L[8*k + i] = l;
3469+
if (scale) {
3470+
for (int iter = 0; iter < 3; ++iter) {
3471+
float id = 1/scale;
3472+
bool changed = false;
3473+
for (int k = 0; k < 2; ++k) {
3474+
uint16_t u = 0;
3475+
for (int i = 0; i < 8; ++i) {
3476+
int l = nearest_int(0.5f*(id*xval[8*k+i]-1));
3477+
l = MAX(0, MIN(kMaxQ-1, l));
3478+
u |= (l << 2*i);
3479+
Laux[8*k + i] = l;
3480+
}
3481+
int grid_index = kmap_q2xs[u];
3482+
if (grid_index < 0) {
3483+
const uint16_t * neighbours = kneighbors_q2xs - kmap_q2xs[u] - 1;
3484+
grid_index = iq2_find_best_neighbour(neighbours, kgrid_q2xs, xval + 8*k, waux + 8*k, scale, Laux + 8*k);
3485+
}
3486+
aux_index[k] = grid_index;
3487+
if (grid_index != index[k]) changed = true;
34463488
}
3447-
int grid_index = kmap_q2xs[u];
3448-
if (grid_index < 0) {
3449-
const uint16_t * neighbours = kneighbors_q2xs - kmap_q2xs[u] - 1;
3450-
grid_index = iq2_find_best_neighbour(neighbours, kgrid_q2xs, xval + 8*k, waux + 8*k, scale, L + 8*k);
3489+
if (!changed) break;
3490+
float sumqx = 0, sumq2 = 0;
3491+
for (int i = 0; i < 16; ++i) {
3492+
float w = weight[i];
3493+
float q = 2*Laux[i] + 1;
3494+
sumqx += w*xval[i]*q;
3495+
sumq2 += w*q*q;
34513496
}
3497+
if (sumq2 > 0 && sumqx*sumqx > best*sumq2) {
3498+
scale = sumqx/sumq2;
3499+
best = scale*sumqx;
3500+
memcpy(L, Laux, 16);
3501+
for (int k = 0; k < 2; ++k) index[k] = aux_index[k];
3502+
}
3503+
else break;
34523504
}
3453-
float sumqx = 0, sumq2 = 0;
3454-
for (int i = 0; i < 16; ++i) {
3455-
float w = weight[i];
3456-
float q = 2*L[i] + 1;
3457-
sumqx += w*xval[i]*q;
3458-
sumq2 += w*q*q;
3459-
}
3460-
if (sumq2 > 0) scale = sumqx/sumq2;
34613505
}
34623506
if (scale < 0) {
34633507
scale = -scale;
@@ -3488,13 +3532,34 @@ static void quantize_row_iq2_xs_impl(const float * GGML_RESTRICT x, void * GGML_
34883532
float d = max_scale/31;
34893533
y[ibl].d = GGML_FP32_TO_FP16(d);
34903534
float id = 1/d;
3535+
float sumqx = 0, sumq2 = 0;
34913536
for (int ib = 0; ib < QK_K/16; ++ib) {
34923537
int l = nearest_int(0.5f*(id*scales[ib]-1));
34933538
l = MAX(0, MIN(15, l));
34943539
if (ib%2 == 0) y[ibl].scales[ib/2] = l;
34953540
else y[ibl].scales[ib/2] |= (l << 4);
3541+
l = 2*l + 1;
3542+
const float * xb = xbl + 16*ib;
3543+
if (quant_weights) {
3544+
const float * qw = quant_weights + QK_K*ibl + 16*ib;
3545+
for (int i = 0; i < 16; ++i) weight[i] = qw[i] * sqrtf(sigma2 + xb[i]*xb[i]);
3546+
} else {
3547+
for (int i = 0; i < 16; ++i) weight[i] = 0.25f*sigma2 + xb[i]*xb[i];
3548+
}
3549+
for (int k = 0; k < 2; ++k) {
3550+
int grid_index = q2[2*ib+k] & 511;
3551+
const int8_t * grid = (const int8_t *)(iq2xs_grid + grid_index);
3552+
const uint8_t signs = ksigns_iq2xs[q2[2*ib+k] >> 9];
3553+
for (int j = 0; j < 8; ++j) {
3554+
float w = weight[8*k+j];
3555+
float q = 0.125f*l*grid[j]*(signs & kmask_iq2xs[j] ? -1.f : 1.f);
3556+
sumqx += w*q*xb[8*k+j];
3557+
sumq2 += w*q*q;
3558+
}
3559+
}
34963560
}
34973561
memcpy(y[ibl].qs, q2, QK_K/4);
3562+
if (sumq2 > 0) y[ibl].d = GGML_FP32_TO_FP16(1.05f*sumqx/sumq2);
34983563

34993564
}
35003565
}
@@ -4300,12 +4365,6 @@ static int iq1_find_best_neighbour2(const uint16_t * GGML_RESTRICT neighbours, c
43004365
return grid_index;
43014366
}
43024367

4303-
static int iq1_sort_helper(const void * left, const void * right) {
4304-
const float * l = left;
4305-
const float * r = right;
4306-
return *l < *r ? -1 : *l > *r ? 1 : 0;
4307-
}
4308-
43094368
#define IQ1S_BLOCK_SIZE 32
43104369
#define IQ1M_BLOCK_SIZE 16
43114370
static void quantize_row_iq1_s_impl(const float * GGML_RESTRICT x, void * GGML_RESTRICT vy, int64_t n, const float * GGML_RESTRICT quant_weights,

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