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Allow q8_0 cache on the CPU for FlashMLA-2 #265

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Merged
merged 1 commit into from
Mar 18, 2025
Merged

Allow q8_0 cache on the CPU for FlashMLA-2 #265

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64 changes: 56 additions & 8 deletions ggml/src/ggml.c
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Original file line number Diff line number Diff line change
Expand Up @@ -10569,17 +10569,65 @@ static void ggml_compute_forward_dup_q(
const struct ggml_compute_params * params,
struct ggml_tensor * dst) {

int64_t nrows = ggml_nrows(dst);
int ith = params->ith;
int nth = params->nth;

if (dst->type == GGML_TYPE_Q8_0 && dst->src[0]->type == GGML_TYPE_Q8_0 &&
ggml_are_same_shape(dst, dst->src[0])) {

// we assume src is transposed and that's why we are here

GGML_ASSERT(dst->ne[0] % QK8_0 == 0);

struct ggml_tensor * const src = dst->src[0];
GGML_ASSERT(src->nb[1] == sizeof(block_q8_0));

float aux[QK8_0];

int64_t n_per_thread = (nrows + nth - 1)/nth;
int64_t first_row = ith*n_per_thread;
if (first_row >= nrows) return;
int64_t last_row = MIN(first_row + n_per_thread, nrows);

int64_t nblock = dst->ne[0] / QK8_0;
for (int64_t ir = first_row; ir < last_row; ++ir) {
int64_t i3 = ir/(dst->ne[1]*dst->ne[2]);
int64_t i2 = (ir - i3*dst->ne[1]*dst->ne[2])/dst->ne[1];
int64_t i1 = ir - i3*dst->ne[1]*dst->ne[2] - i2*dst->ne[1];
int ib0 = i1/QK8_0;
int iq0 = i1%QK8_0;
for (int ib = 0; ib < nblock; ++ib) {
block_q8_0 * dst_q8 = (block_q8_0 *)((char *)dst->data + i1*dst->nb[1] + i2*dst->nb[2] + i3*dst->nb[3]);
float amax = 0;
for (int j = 0; j < QK8_0; ++j) {
int64_t i0 = ib*QK8_0 + j;
const block_q8_0 * src_q8 = (const block_q8_0 *)((const char *)src->data + i0*src->nb[0] + i2*src->nb[2] + i3*src->nb[3]);
float xi = GGML_FP16_TO_FP32(src_q8[ib0].d) * src_q8[ib0].qs[iq0];
aux[j] = xi;
xi = fabsf(xi);
amax = MAX(amax, xi);
}
float d = amax/127;
dst_q8[ib].d = GGML_FP32_TO_FP16(d);
if (d > 0) {
float id = 1/d;
for (int j = 0; j < QK8_0; ++j) dst_q8[ib].qs[j] = roundf(id*aux[j]);
} else {
memset(dst_q8[ib].qs, 0, QK8_0);
}
}
}
return;
}

GGML_ASSERT(dst->type == GGML_TYPE_F32);
struct ggml_tensor * src0 = dst->src[0];
GGML_ASSERT(src0->ne[0] == dst->ne[0] && src0->nb[0] == ggml_type_size(src0->type));

ggml_to_float_t to_float = type_traits[src0->type].to_float;
GGML_ASSERT(to_float != NULL);

int64_t nrows = ggml_nrows(dst);
int ith = params->ith;
int nth = params->nth;

int64_t n_per_thread = (nrows + nth - 1)/nth;
int64_t first_row = ith*n_per_thread;
if (first_row >= nrows) return;
Expand Down Expand Up @@ -10607,13 +10655,13 @@ static void ggml_compute_forward_dup(

const struct ggml_tensor * src0 = dst->src[0];

if (src0->type == dst->type) {
ggml_compute_forward_dup_bytes(params, dst);
if (ggml_is_quantized(src0->type)) {
ggml_compute_forward_dup_q(params, dst);
return;
}

if (ggml_is_quantized(src0->type)) {
ggml_compute_forward_dup_q(params, dst);
if (src0->type == dst->type) {
ggml_compute_forward_dup_bytes(params, dst);
return;
}

Expand Down