haraldwolff/llama.cpp
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metal : new q4_0 matrix-vector kernel (#2188)

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Prefetch data to improve GPU utilization. ~48% faster for 33B model.
This commit is contained in:
Shouzheng Liu 2023-07-12 16:10:55 -04:00 committed by GitHub
parent 975221e954
commit 1cbf561466
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GPG key ID: 4AEE18F83AFDEB23
2 changed files with 61 additions and 49 deletions
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5
ggml-metal.m
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@ -739,7 +739,10 @@ void ggml_metal_graph_compute(
[encoder setBytes:&ne0 length:sizeof(ne0) atIndex:13];
[encoder setBytes:&ne1 length:sizeof(ne1) atIndex:14];
if (src0t == GGML_TYPE_Q4_0 || src0t == GGML_TYPE_Q4_1) {
if (src0t == GGML_TYPE_Q4_0) {
[encoder dispatchThreadgroups:MTLSizeMake(ne01 / 8+((ne01 % 8) & 0x01), ne11, 1) threadsPerThreadgroup:MTLSizeMake(nth0, nth1, 1)];
}
else if (src0t == GGML_TYPE_Q4_1) {
[encoder setThreadgroupMemoryLength:nth0*nth1*sizeof(float) atIndex:0];
[encoder dispatchThreadgroups:MTLSizeMake(ne01, ne11, 1) threadsPerThreadgroup:MTLSizeMake(nth0, nth1, 1)];
}

105
ggml-metal.metal
View file

@ -365,6 +365,10 @@ kernel void kernel_rms_norm(
}
}
// putting them in the kernel cause a significant performance penalty
#define N_DST 4 // each SIMD group works on 4 rows
#define N_SIMDGROUP 2 // number of SIMD groups in a thread group
#define N_SIMDWIDTH 32 // assuming SIMD group size is 32
kernel void kernel_mul_mat_q4_0_f32(
device const void * src0,
device const float * src1,
@ -372,64 +376,69 @@ kernel void kernel_mul_mat_q4_0_f32(
constant int64_t & ne00,
constant int64_t & ne10,
constant int64_t & ne0,
threadgroup float * sum [[threadgroup(0)]],
constant int64_t & ne01[[buffer(4)]],
uint2 tgpig[[threadgroup_position_in_grid]],
uint2 tpitg[[thread_position_in_threadgroup]],
uint2 tptg[[threads_per_threadgroup]]) {
uint tiisg[[thread_index_in_simdgroup]],
uint sgitg[[simdgroup_index_in_threadgroup]]) {
const int nb = ne00/QK4_0;
const int64_t r0 = tgpig.x;
const int64_t r1 = tgpig.y;
device const block_q4_0 * x = (device const block_q4_0 *) src0 + r0*nb;
const int r0 = tgpig.x;
const int r1 = tgpig.y;
device const block_q4_0 * x = (device const block_q4_0 *) src0 + (r0 * N_SIMDGROUP + sgitg) * N_DST * nb;
device const float * y = (device const float *) src1 + r1*ne10;
block_q4_0 qb_curr, qb_next;
float4 y_curr[8]; // src1 vector cache
float sumf[N_DST]={0.f}, all_sum;
thread float * yl=(thread float *)y_curr;
const int nth = tptg.x*tptg.y;
const int ith = tptg.y*tpitg.x + tpitg.y;
const int ix = tpitg.y/4; // 0 or 1
const int iy = tpitg.y - 4*ix; // 0...3
const int first = 4 * iy;
float sumf = 0;
for (int i = 2*tpitg.x + ix; i < nb; i += 2*tptg.x) {
const float d = (float)x[i].d;
device const uint8_t * xl = x[i].qs + first;
device const float * yl = y + i * QK4_0 + first;
float2 acc = {0.0f, 0.0f};
for (int j = 0; j < 4; ++j) {
acc[0] += yl[j] * (xl[j] & 0xF) + yl[j+16] * (xl[j] >> 4);
acc[1] += yl[j] + yl[j+16];
// bootstrap
qb_curr = x[tiisg];
// each thread in a SIMD group deals with 1 block.
for (int column = 0; column < nb / N_SIMDWIDTH; column++) {
for (int i = 0; i < QK4_0 / 4; i++) {
y_curr[i] = *((device float4 *)(y + N_SIMDWIDTH * (tiisg + column * QK4_0) + 4 * i));
}
sumf += d * (acc[0] - 8.f*acc[1]);
for (int row = 0; row < N_DST; row++) {
// prefetch next x block
qb_next = x[tiisg + ((row + 1) % N_DST) * nb + (column + ((row + 1) / N_DST)) * N_SIMDWIDTH];
// calculate
float d = qb_curr.d;
float2 acc = {0.0f, 0.0f};
for (int i = 0; i < 16; i++) {
acc[0] += yl[i] * (qb_curr.qs[i] & 0xF) + yl[i+16] * (qb_curr.qs[i] >> 4);
acc[1] += yl[i] + yl[i+16];
}
sumf[row] += d * (acc[0] - 8.f*acc[1]);
qb_curr = qb_next;
}
}
sum[ith] = sumf;
for (int i = 0; i < QK4_0 / 4; i++) {
y_curr[i] = *((device float4 *)(y + N_SIMDWIDTH * (tiisg + (nb / N_SIMDWIDTH) * QK4_0) + 4 * i));
}
//
// Accumulate the sum from all threads in the threadgroup
//
threadgroup_barrier(mem_flags::mem_threadgroup);
if (ith%4 == 0) {
sum[ith] += sum[ith+1] + sum[ith+2] + sum[ith+3];
}
threadgroup_barrier(mem_flags::mem_threadgroup);
if (ith%16 == 0) {
sum[ith] += sum[ith+4] + sum[ith+8] + sum[ith+12];
}
threadgroup_barrier(mem_flags::mem_threadgroup);
if (ith == 0) {
for (int i = 16; i < nth; i += 16) sum[0] += sum[i];
dst[r1*ne0 + r0] = sum[0];
for (int row = 0; row < N_DST; row++) {
// prefetch next x block
qb_next = x[tiisg + ((row + 1) % N_DST) * nb + (nb / N_SIMDWIDTH + ((row + 1) / N_DST)) * N_SIMDWIDTH];
// calculate
float d = qb_curr.d;
float2 acc = {0.0f, 0.0f};
for (int i = 0; i < 16; i++) {
acc[0] += yl[i] * (qb_curr.qs[i] & 0xF) + yl[i+16] * (qb_curr.qs[i] >> 4);
acc[1] += yl[i] + yl[i+16];
}
if (tiisg < nb % N_SIMDWIDTH) {
sumf[row] += d * (acc[0] - 8.f*acc[1]);
}
qb_curr = qb_next;
all_sum = simd_sum(sumf[row]);
if (tiisg == 0 && ((r0 * N_SIMDGROUP + sgitg) * N_DST + row) < ne01) {
dst[r1*ne0 + (r0 * N_SIMDGROUP + sgitg) * N_DST + row] = all_sum;
}
}
}