NEON Flash Attention: quantized K*Q for q4_0

I could finally take advantage of the matrix multiplication
templates. We get quite a bit of speedup that way for q4_0:
For Gemma-2b using mul_mat_qX_0_q8_0<DequantizerQ40, q_step>
results in PP-2048 = 287 t/s vs 268 t/s when converting the
q4_0 k-cache and Q to fp16 and using fp16 multiplication.
This commit is contained in:
Iwan Kawrakow
2024-09-12 09:12:35 +02:00
parent 2dee479c44
commit 0b6d6541d7

View File

@@ -6548,6 +6548,120 @@ struct HelperF16 final : public BaseHelper<step> {
}
};
void quantize_row_q8_0(const float * x, block_q8_0 * y, int k) {
const int nb = k / QK8_0;
const int nb4 = 4*(nb/4);
#if defined(__aarch64__)
block_q8_0_x4 * y4 = (block_q8_0_x4 *)y;
for (int i = 0; i < nb; i++) {
int i4 = i/4, ir = i%4;
float32x4_t srcv [8];
float32x4_t asrcv[8];
float32x4_t amaxv[8];
for (int j = 0; j < 8; j++) srcv[j] = vld1q_f32(x + i*32 + 4*j);
for (int j = 0; j < 8; j++) asrcv[j] = vabsq_f32(srcv[j]);
for (int j = 0; j < 4; j++) amaxv[2*j] = vmaxq_f32(asrcv[2*j], asrcv[2*j+1]);
for (int j = 0; j < 2; j++) amaxv[4*j] = vmaxq_f32(amaxv[4*j], amaxv[4*j+2]);
for (int j = 0; j < 1; j++) amaxv[8*j] = vmaxq_f32(amaxv[8*j], amaxv[8*j+4]);
const float amax = vmaxvq_f32(amaxv[0]);
const float d = amax / ((1 << 7) - 1);
const float id = d ? 1.0f/d : 0.0f;
if (i < nb4) {
y4[i4].d[ir] = GGML_FP32_TO_FP16(d);
} else {
y[i].d = GGML_FP32_TO_FP16(d);
}
for (int j = 0; j < 8; j++) {
const float32x4_t v = vmulq_n_f32(srcv[j], id);
const int32x4_t vi = vcvtnq_s32_f32(v);
if (i < nb4) {
y4[i4].qs[32*ir + 4*j + 0] = vgetq_lane_s32(vi, 0);
y4[i4].qs[32*ir + 4*j + 1] = vgetq_lane_s32(vi, 1);
y4[i4].qs[32*ir + 4*j + 2] = vgetq_lane_s32(vi, 2);
y4[i4].qs[32*ir + 4*j + 3] = vgetq_lane_s32(vi, 3);
} else {
y[i].qs[4*j + 0] = vgetq_lane_s32(vi, 0);
y[i].qs[4*j + 1] = vgetq_lane_s32(vi, 1);
y[i].qs[4*j + 2] = vgetq_lane_s32(vi, 2);
y[i].qs[4*j + 3] = vgetq_lane_s32(vi, 3);
}
}
}
#else
block_q8_0_x4 * y4 = (block_q8_0_x4 *)y;
for (int i = 0; i < nb; i++) {
int i4 = i/4, ir = i%4;
// Load elements into 4 AVX vectors
__m256 v0 = _mm256_loadu_ps( x );
__m256 v1 = _mm256_loadu_ps( x + 8 );
__m256 v2 = _mm256_loadu_ps( x + 16 );
__m256 v3 = _mm256_loadu_ps( x + 24 );
x += 32;
const __m256 signBit = _mm256_set1_ps( -0.0f );
__m256 maxAbs = _mm256_andnot_ps( signBit, v0 );
maxAbs = _mm256_max_ps( maxAbs, _mm256_andnot_ps( signBit, v1 ) );
maxAbs = _mm256_max_ps( maxAbs, _mm256_andnot_ps( signBit, v2 ) );
maxAbs = _mm256_max_ps( maxAbs, _mm256_andnot_ps( signBit, v3 ) );
__m128 max4 = _mm_max_ps( _mm256_extractf128_ps( maxAbs, 1 ), _mm256_castps256_ps128( maxAbs ) );
max4 = _mm_max_ps( max4, _mm_movehl_ps( max4, max4 ) );
max4 = _mm_max_ss( max4, _mm_movehdup_ps( max4 ) );
const float maxScalar = _mm_cvtss_f32( max4 );
const float d = maxScalar / 127.f;
if (i < nb4) {
y4[i4].d[ir] = GGML_FP32_TO_FP16(d);
} else {
y[i].d = GGML_FP32_TO_FP16(d);
}
const float id = ( maxScalar != 0.0f ) ? 127.f / maxScalar : 0.0f;
const __m256 mul = _mm256_set1_ps( id );
v0 = _mm256_mul_ps( v0, mul );
v1 = _mm256_mul_ps( v1, mul );
v2 = _mm256_mul_ps( v2, mul );
v3 = _mm256_mul_ps( v3, mul );
v0 = _mm256_round_ps( v0, _MM_ROUND_NEAREST );
v1 = _mm256_round_ps( v1, _MM_ROUND_NEAREST );
v2 = _mm256_round_ps( v2, _MM_ROUND_NEAREST );
v3 = _mm256_round_ps( v3, _MM_ROUND_NEAREST );
__m256i i0 = _mm256_cvtps_epi32( v0 );
__m256i i1 = _mm256_cvtps_epi32( v1 );
__m256i i2 = _mm256_cvtps_epi32( v2 );
__m256i i3 = _mm256_cvtps_epi32( v3 );
// Convert int32 to int16
i0 = _mm256_packs_epi32( i0, i1 ); // 0, 1, 2, 3, 8, 9, 10, 11, 4, 5, 6, 7, 12, 13, 14, 15
i2 = _mm256_packs_epi32( i2, i3 ); // 16, 17, 18, 19, 24, 25, 26, 27, 20, 21, 22, 23, 28, 29, 30, 31
// Convert int16 to int8
i0 = _mm256_packs_epi16( i0, i2 ); // 0, 1, 2, 3, 8, 9, 10, 11, 16, 17, 18, 19, 24, 25, 26, 27, 4, 5, 6, 7, 12, 13, 14, 15, 20, 21, 22, 23, 28, 29, 30, 31
// We got our precious signed bytes, but the order is now wrong
// These AVX2 pack instructions process 16-byte pieces independently
// The following instruction is fixing the order
const __m256i perm = _mm256_setr_epi32( 0, 4, 1, 5, 2, 6, 3, 7 );
i0 = _mm256_permutevar8x32_epi32( i0, perm );
if (i < nb4) {
_mm256_storeu_si256((__m256i *)y4[i4].qs + ir, i0);
} else {
_mm256_storeu_si256((__m256i *)y[i].qs, i0);
}
}
#endif
}
template <int D, int step>
struct HelperQ80 final : public BaseHelper<step> {
static_assert(step == QK8_0);
@@ -6653,6 +6767,15 @@ struct HelperQ80 final : public BaseHelper<step> {
load(l1+0, vk+0);
load(l1+1, vk+D/F16::block_size);
}
static inline void convert(int nq, int stride_q, const float * q, block_q8_0 * y) {
GGML_ASSERT(nq <= step);
for (int i = 0; i < nq; ++i) {
quantize_row_q8_0(q, y, D);
q += stride_q;
y += D/QK8_0;
}
}
};
template <int D, int step>
@@ -6929,6 +7052,65 @@ struct FlashMS {
}
}
float smax = vmaxvq_f32(vmax);
if (smax == -INFINITY) {
std::memset(cache + k_step*j, 0, k_step*sizeof(float));
need_scaling[j] = M[j] == -INFINITY ? 2 : 0;
return;
}
need_scaling[j] = 0;
if (smax > M[j]) {
if (M[j] > -INFINITY) {
float m = expf(M[j] - smax);
vms[j] = F16::set1(m);
need_scaling[j] = 1;
S[j] *= m;
} else {
need_scaling[j] = 2;
S[j] = 0;
}
M[j] = smax;
}
auto vm = vdupq_n_f32(M[j]);
auto vsum = vdupq_n_f32(0);
for (int l = 0; l < k_step/4; ++l) {
vk[l] = v_expf(vsubq_f32(vk[l], vm));
vsum = vaddq_f32(vsum, vk[l]);
F16::store(cache + k_step*j + 4*l, vk[l]);
}
S[j] += vaddvq_f32(vsum);
}
inline void update_M_S(int j, float32x4_t * vk, const char * mask) {
{
auto vzero = vdupq_n_f32(0);
auto vinf = vdupq_n_f32(-INFINITY);
for (int l = 0; l < k_step/8; ++l) {
auto vm = vceqq_f16(vzero, vld1q_f16((const float16_t *)mask + 8*l));
auto vm1 = vzip1q_u16(vm, vm);
auto vm2 = vzip2q_u16(vm, vm);
auto kq = vld1q_f32_x2(cache + k_step*j + 8*l);
vk[2*l+0] = vreinterpretq_f32_u32(vorrq_u32(vandq_u32(vreinterpretq_u32_f32(kq.val[0]), vm1),
vbicq_u32(vinf, vm1)));
vk[2*l+1] = vreinterpretq_f32_u32(vorrq_u32(vandq_u32(vreinterpretq_u32_f32(kq.val[1]), vm2),
vbicq_u32(vinf, vm2)));
}
}
float32x4_t vmax = vdupq_n_f32(-INFINITY);
auto vscale32 = vcvt_f32_f16(vget_low_f16(vscale));
if (softcap <= 0.0f) {
for (int l = 0; l < k_step/4; ++l) {
vk[l] = vmulq_f32(vscale32, vk[l]);
vmax = vmaxq_f32(vmax, vk[l]);
}
} else {
auto v_softcap = vdupq_n_f32(softcap);
for (int l = 0; l < k_step/4; ++l) {
vk[l] = vmulq_f32(vscale32, vk[l]);
vk[l] = vmulq_f32(v_softcap, v_tanh(vk[l]));
vmax = vmaxq_f32(vmax, vk[l]);
}
}
float smax = vmaxvq_f32(vmax);
if (smax == -INFINITY) {
std::memset(cache + k_step*j, 0, k_step*sizeof(float));
@@ -7278,6 +7460,74 @@ struct FlashQKfp32 {
}
}
#endif
static inline void mul_mask_kq(const HelperQ40<D, k_step>& kh, int stride_m,
const block_q8_0 * q, const char * mask, FlashMS<q_step, k_step>& fms) {
static_assert(q_step <= 8);
DataInfo info{fms.cache, (const char *)q, k_step, (D/QK8_0)*sizeof(block_q8_0), 0, 1, nullptr};
mul_mat_qX_0_q8_0<DequantizerQ40, q_step>(D, kh.block, kh.stride, info, k_step);
//auto vinf = vdupq_n_f32(-INFINITY);
//auto vzero = vdupq_n_f16(0);
//for (int j = 0; j < q_step; ++j) {
// const ggml_half * mp = (const ggml_half *)(mask + stride_m*j);
// for (int l = 0; l < k_step/8; ++l) {
// auto vm = vceqq_f16(vzero, vld1q_f16((const float16_t *)mp + 8*l));
// auto vm1 = vzip1q_u16(vm, vm);
// auto vm2 = vzip2q_u16(vm, vm);
// auto kq = vld1q_f32_x2(fms.cache + k_step*j + 8*l);
// kq.val[0] = vreinterpretq_f32_u32(vorrq_u32(vandq_u32(vreinterpretq_u32_f32(kq.val[0]), vm1),
// vbicq_u32(vinf, vm1)));
// kq.val[1] = vreinterpretq_f32_u32(vorrq_u32(vandq_u32(vreinterpretq_u32_f32(kq.val[1]), vm2),
// vbicq_u32(vinf, vm2)));
// vst1q_f32_x2(fms.cache + k_step*j + 8*l, kq);
// }
// //for (int l = 0; l < k_step; ++l) {
// // if (mp[l] == fms.h_inf) fms.cache[k_step*j + l] = -INFINITY;
// //}
//}
#ifdef __aarch64__
float32x4_t vk[k_step/4];
for (int j = 0; j < q_step; ++j) {
fms.update_M_S(j, vk, mask + stride_m*j);
}
#else
F16::Data vk[k_step/F16::block_size];
for (int j = 0; j < q_step; ++j) {
fms.update_M_S(j, vk);
}
#endif
}
static inline void mul_mask_kq(int nq, const HelperQ40<D, k_step>& kh, int stride_m,
const block_q8_0 * q, const char * mask, FlashMS<q_step, k_step>& fms) {
GGML_ASSERT(nq < 8);
DataInfo info{fms.cache, (const char *)q, D*sizeof(float), (D/QK8_0)*sizeof(block_q8_0), 0, 1, nullptr};
switch (nq) {
case 1: mul_mat_qX_0_q8_0<DequantizerQ40, 1>(D, kh.block, kh.stride, info, k_step); break;
case 2: mul_mat_qX_0_q8_0<DequantizerQ40, 2>(D, kh.block, kh.stride, info, k_step); break;
case 3: mul_mat_qX_0_q8_0<DequantizerQ40, 3>(D, kh.block, kh.stride, info, k_step); break;
case 4: mul_mat_qX_0_q8_0<DequantizerQ40, 4>(D, kh.block, kh.stride, info, k_step); break;
case 5: mul_mat_qX_0_q8_0<DequantizerQ40, 5>(D, kh.block, kh.stride, info, k_step); break;
case 6: mul_mat_qX_0_q8_0<DequantizerQ40, 6>(D, kh.block, kh.stride, info, k_step); break;
case 7: mul_mat_qX_0_q8_0<DequantizerQ40, 7>(D, kh.block, kh.stride, info, k_step); break;
}
//for (int j = 0; j < nq; ++j) {
// const ggml_half * mp = (const ggml_half *)(mask + stride_m*j);
// for (int l = 0; l < k_step; ++l) {
// if (mp[l] == fms.h_inf) fms.cache[k_step*j + l] = -INFINITY;
// }
//}
#ifdef __aarch64__
float32x4_t vk[k_step/4];
for (int j = 0; j < nq; ++j) {
fms.update_M_S(j, vk, mask + stride_m*j);
}
#else
F16::Data vk[k_step/F16::block_size];
for (int j = 0; j < nq; ++j) {
fms.update_M_S(j, vk);
}
#endif
}
};
template <int D, int q_step, int k_step, typename KHelper, typename VHelper, typename KQHelper>
@@ -7337,6 +7587,49 @@ void compute_helper(KHelper& kh, VHelper& vh, int nq1, int nk1, int stride_q, in
}
}
template <int D, int q_step, int k_step, typename VHelper, typename KQHelper>
void compute_helper_q(HelperQ40<D, k_step>& kh, VHelper& vh, int nq1, int nk1, int stride_q, int stride_m, int stride_qkv,
FlashMS<q_step, k_step>& fms,
FlashQKV<D, q_step, k_step>& fqkv,
const float * q, const char * mask, float * qkv) {
block_q8_0 q80[q_step*(D/QK8_0)];
for (int i1 = 0; i1 < nq1/q_step; ++i1) {
fms.init_qstep();
kh.reset_block();
vh.reset_block();
HelperQ80<D, QK8_0>::convert(q_step, stride_q, q, q80);
auto mr = mask;
for (int k1 = 0; k1 < nk1/k_step; ++k1) {
KQHelper::mul_mask_kq(kh, stride_m, q80, mr, fms);
fqkv.accumulate_qkv(vh, fms);
kh.next_block();
vh.next_block();
mr += k_step*sizeof(ggml_half);
}
fqkv.normalize_and_store(fms, stride_qkv, qkv);
q += q_step*stride_q;
mask += q_step*stride_m;
qkv += q_step*stride_qkv;
}
int n_left = nq1 - q_step*(nq1/q_step);
if (n_left > 0) {
fms.init_qstep();
kh.reset_block();
vh.reset_block();
HelperQ80<D, QK8_0>::convert(n_left, stride_q, q, q80);
auto mr = mask;
for (int k1 = 0; k1 < nk1/k_step; ++k1) {
KQHelper::mul_mask_kq(n_left, kh, stride_m, q80, mr, fms);
fqkv.accumulate_qkv(n_left, vh, fms);
kh.next_block();
vh.next_block();
mr += k_step*sizeof(ggml_half);
}
fqkv.normalize_and_store(fms, n_left, stride_qkv, qkv);
}
}
// Some of the methods in FlashAttn have two identical implementations that only differ by
// one version using a loop over the template parameter q_step, while the other using a loop
// over an input parameter nq (these are loops over the rows of q^T). I dislike this a lot,
@@ -7358,8 +7651,13 @@ struct FlashAttn {
template <typename KHelper, typename VHelper>
void compute(KHelper& kh, VHelper& vh, int nq1, int nk1, int stride_q, int stride_m, int stride_qkv,
const float * q, const char * mask, float * qkv) {
compute_helper<D, q_step, k_step, KHelper, VHelper, FlashQKfp32<D, q_step, k_step>>(
kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, fms, fqkv, q, mask, qkv);
if constexpr (std::is_same_v<KHelper, HelperQ40<D, k_step>>) {
compute_helper_q<D, q_step, k_step, VHelper, FlashQKfp32<D, q_step, k_step>>(
kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, fms, fqkv, q, mask, qkv);
} else {
compute_helper<D, q_step, k_step, KHelper, VHelper, FlashQKfp32<D, q_step, k_step>>(
kh, vh, nq1, nk1, stride_q, stride_m, stride_qkv, fms, fqkv, q, mask, qkv);
}
}
FlashMS<q_step, k_step> fms;