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metal : separate scale and mask from QKT in FA kernel (#9189)

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* metal : separate scale and mask from QKT in FA kernel

* metal : ne01 check no longer necessary

* metal : keep data in local memory
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Georgi Gerganov 2024-08-26 18:31:02 +03:00 committed by GitHub
parent fc18425b6a
commit 06658ad7c3
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1 changed files with 13 additions and 22 deletions
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ggml/src/ggml-metal.metal
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@ -2261,24 +2261,6 @@ kernel void kernel_flash_attn_ext_f16(
}
simdgroup_store(mqk, ss + 8*cc, TF, 0, false);
const short tx = tiisg%4;
const short ty = tiisg/4;
// mqk = mqk*scale
ss[8*cc + ty*TF + 2*tx + 0] *= scale;
ss[8*cc + ty*TF + 2*tx + 1] *= scale;
if (logit_softcap != 0.0f) {
ss[8*cc + ty*TF + 2*tx + 0] = logit_softcap*precise::tanh(ss[8*cc + ty*TF + 2*tx + 0]);
ss[8*cc + ty*TF + 2*tx + 1] = logit_softcap*precise::tanh(ss[8*cc + ty*TF + 2*tx + 1]);
}
if (mask != q) {
// mqk = mqk + mask*slope
ss[8*cc + ty*TF + 2*tx + 0] += slope*mp[ic + 8*cc + ty*nb31/sizeof(half) + 2*tx + 0];
ss[8*cc + ty*TF + 2*tx + 1] += slope*mp[ic + 8*cc + ty*nb31/sizeof(half) + 2*tx + 1];
}
}
}
@ -2290,10 +2272,19 @@ kernel void kernel_flash_attn_ext_f16(
float ms[Q];
for (short j = 0; j < Q; ++j) {
const short p = tiisg;
const float m = M[j];
const float s = ss[j*TF + p];
// scale and apply the logitcap / mask
float s = ss[j*TF + tiisg]*scale;
if (logit_softcap != 0.0f) {
s = logit_softcap*precise::tanh(s);
}
if (mask != q) {
// mqk = mqk + mask*slope
s += slope*mp[ic + j*nb31/sizeof(half) + tiisg];
}
smax = simd_max(max(smax, s));
M[j] = simd_max(max(M[j], s));
@ -2304,7 +2295,7 @@ kernel void kernel_flash_attn_ext_f16(
S[j] = S[j]*ms[j] + simd_sum(vs);
// the P matrix from the paper (Q rows, C columns)
ss[j*TF + p] = vs;
ss[j*TF + tiisg] = vs;
}
// create a QxQ diagonal matrix for rescaling the output