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Merged
merged 2 commits into from
Nov 17, 2025
+87 −41
Merged

metal : faster argsort #17315

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f06a8d3
metal : faster argsort
ggerganov Nov 17, 2025
f2c5763
cont : keep data in registers
ggerganov Nov 17, 2025
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2 changes: 0 additions & 2 deletions ggml/src/ggml-metal/ggml-metal-ops.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -3605,8 +3605,6 @@ int ggml_metal_op_argsort(ggml_metal_op_t ctx, int idx) {
ggml_metal_encoder_set_buffer (enc, bid_dst, 2);
ggml_metal_encoder_set_buffer (enc, bid_tmp, 3);

ggml_metal_encoder_set_threadgroup_memory_size(enc, 0, 0);

ggml_metal_encoder_dispatch_threadgroups(enc, nm*ne01, ne02, ne03, nth, 1, 1);

std::swap(bid_dst, bid_tmp);
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126 changes: 87 additions & 39 deletions ggml/src/ggml-metal/ggml-metal.metal
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Expand Up @@ -4628,12 +4628,13 @@ kernel void kernel_argsort_merge_f32_i32(
uint3 tgpig[[threadgroup_position_in_grid]],
ushort3 tpitg[[thread_position_in_threadgroup]],
ushort3 ntg[[threads_per_threadgroup]]) {
int im = tgpig[0] / args.ne01;
int i01 = tgpig[0] % args.ne01;
int i02 = tgpig[1];
int i03 = tgpig[2];

const int start = im * (2*args.len);
const int im = tgpig[0] / args.ne01;
const int i01 = tgpig[0] % args.ne01;
const int i02 = tgpig[1];
const int i03 = tgpig[2];

const int start = im * (2 * args.len);

const int len0 = MIN(args.len, MAX(0, args.ne00 - (int)(start)));
const int len1 = MIN(args.len, MAX(0, args.ne00 - (int)(start + args.len)));
Expand All @@ -4657,54 +4658,101 @@ kernel void kernel_argsort_merge_f32_i32(
+ args.nb02*i02
+ args.nb03*i03);

for (int k = tpitg.x; k < (int) total; k += ntg.x) {
// find partition (i,j) such that i+j = k
int low = k > len1 ? k - len1 : 0;
int high = MIN(k, len0);
if (total == 0) {
return;
}

while (low < high) {
const int mid = (low + high) >> 1;
const int chunk = (total + ntg.x - 1) / ntg.x;

const int32_t idx0 = tmp0[mid];
const int32_t idx1 = tmp1[k - mid - 1];
const int k0 = tpitg.x * chunk;
const int k1 = min(k0 + chunk, total);

const float val0 = src0_row[idx0];
const float val1 = src0_row[idx1];
if (k0 >= total) {
return;
}

if (order == GGML_SORT_ORDER_ASC) {
if (val0 <= val1) {
low = mid + 1;
} else {
high = mid;
}
} else {
if (val0 >= val1) {
low = mid + 1;
} else {
high = mid;
}
}
int low = k0 > len1 ? k0 - len1 : 0;
int high = MIN(k0, len0);

// binary-search partition (i, j) such that i + j = k
while (low < high) {
const int mid = (low + high) >> 1;

const int32_t idx0 = tmp0[mid];
const int32_t idx1 = tmp1[k0 - mid - 1];

const float val0 = src0_row[idx0];
const float val1 = src0_row[idx1];

bool take_left;
if (order == GGML_SORT_ORDER_ASC) {
take_left = (val0 <= val1);
} else {
take_left = (val0 >= val1);
}

const int i = low;
const int j = k - i;
if (take_left) {
low = mid + 1;
} else {
high = mid;
}
}

int i = low;
int j = k0 - i;

// keep the merge fronts into registers
int32_t idx0 = 0;
float val0 = 0.0f;
if (i < len0) {
idx0 = tmp0[i];
val0 = src0_row[idx0];
}

int32_t idx1 = 0;
float val1 = 0.0f;
if (j < len1) {
idx1 = tmp1[j];
val1 = src0_row[idx1];
}

for (int k = k0; k < k1; ++k) {
int32_t out_idx;

if (i >= len0) {
out_idx = tmp1[j];
while (k < k1) {
dst[k++] = tmp1[j++];
}
break;
} else if (j >= len1) {
out_idx = tmp0[i];
while (k < k1) {
dst[k++] = tmp0[i++];
}
break;
} else {
const int32_t idx0 = tmp0[i];
const int32_t idx1 = tmp1[j];
bool take_left;

const float val0 = src0_row[idx0];
const float val1 = src0_row[idx1];
if (order == GGML_SORT_ORDER_ASC) {
take_left = (val0 <= val1);
} else {
take_left = (val0 >= val1);
}

out_idx = (order == GGML_SORT_ORDER_ASC)
? (val0 <= val1 ? idx0 : idx1)
: (val0 >= val1 ? idx0 : idx1);
if (take_left) {
out_idx = idx0;
++i;
if (i < len0) {
idx0 = tmp0[i];
val0 = src0_row[idx0];
}
} else {
out_idx = idx1;
++j;
if (j < len1) {
idx1 = tmp1[j];
val1 = src0_row[idx1];
}
}
}

dst[k] = out_idx;
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