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context : restore preemptive sched reset when LLAMA_SET_ROWS=0 #14870

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Merged
merged 1 commit into from
Jul 25, 2025
Merged

context : restore preemptive sched reset when LLAMA_SET_ROWS=0 #14870

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14 changes: 13 additions & 1 deletion src/llama-context.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -105,7 +105,7 @@ llama_context::llama_context(

{
const char * LLAMA_SET_ROWS = getenv("LLAMA_SET_ROWS");
const bool supports_set_rows = LLAMA_SET_ROWS ? (atoi(LLAMA_SET_ROWS) != 0) : false;
supports_set_rows = LLAMA_SET_ROWS ? (atoi(LLAMA_SET_ROWS) != 0) : false;

if (!supports_set_rows && !cparams.kv_unified) {
LLAMA_LOG_WARN("%s: non-unified KV cache requires ggml_set_rows() - forcing unified KV cache\n", __func__);
Expand Down Expand Up @@ -891,6 +891,12 @@ int llama_context::encode(const llama_batch & batch_inp) {
}
}

if (!supports_set_rows) {
// Reset state for the next token before backend sync, to allow the CPU activities in the reset to
// overlap with device computation.
ggml_backend_sched_reset(sched.get());
}

// TODO: hacky solution
if (model.arch == LLM_ARCH_T5 && t_embd) {
//cross.t_embd = t_embd;
Expand Down Expand Up @@ -1230,6 +1236,12 @@ int llama_context::decode(const llama_batch & batch_inp) {
// wait for the computation to finish (automatically done when obtaining the model output)
//synchronize();

if (!supports_set_rows) {
// Reset state for the next token before backend sync, to allow the CPU activities in the reset to
// overlap with device computation.
ggml_backend_sched_reset(sched.get());
}

return 0;
}

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4 changes: 4 additions & 0 deletions src/llama-context.h
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Expand Up @@ -278,6 +278,10 @@ struct llama_context {

bool has_evaluated_once = false;

// env: LLAMA_SET_ROWS (temporary)
// ref: https://github.com/ggml-org/llama.cpp/pull/14285
bool supports_set_rows = false;

// perf
mutable int64_t t_start_us = 0;
mutable int64_t t_load_us = 0;
Expand Down
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