kv-cache : support attention rotation for heterogeneous iSWA (#21513)

* kv-cache : support attention rotation for heterogeneous iSWA

* cont : remove assert

src/llama-graph.cpp

@@ -511,6 +511,14 @@ void llm_graph_input_attn_kv_iswa::set_input(const llama_ubatch * ubatch) {
     if (self_v_rot) {
         mctx->get_base()->set_input_v_rot(self_v_rot);
     }
+
+    if (self_k_rot_swa) {
+        mctx->get_swa()->set_input_k_rot(self_k_rot_swa);
+    }
+
+    if (self_v_rot_swa) {
+        mctx->get_swa()->set_input_v_rot(self_v_rot_swa);
+    }
 }
 
 bool llm_graph_input_attn_kv_iswa::can_reuse(const llm_graph_params & params) {
@@ -681,6 +689,14 @@ void llm_graph_input_mem_hybrid_iswa::set_input(const llama_ubatch * ubatch) {
         attn_ctx->get_base()->set_input_v_rot(inp_attn->self_v_rot);
     }
 
+    if (inp_attn->self_k_rot_swa) {
+        attn_ctx->get_swa()->set_input_k_rot(inp_attn->self_k_rot_swa);
+    }
+
+    if (inp_attn->self_v_rot_swa) {
+        attn_ctx->get_swa()->set_input_v_rot(inp_attn->self_v_rot_swa);
+    }
+
     const int64_t n_rs = mctx->get_recr()->get_n_rs();
 
     if (inp_rs->s_copy) {
@@ -2233,15 +2249,20 @@ ggml_tensor * llm_graph_context::build_attn(
         ggml_tensor * v_mla,
             float     kq_scale,
             int       il) const {
-    if (inp->self_k_rot) {
-        q_cur = ggml_mul_mat_aux(ctx0, q_cur, inp->self_k_rot);
+    const bool is_swa = hparams.is_swa(il);
+
+    auto * k_rot = is_swa ? inp->self_k_rot_swa : inp->self_k_rot;
+    auto * v_rot = is_swa ? inp->self_v_rot_swa : inp->self_v_rot;
+
+    if (k_rot) {
+        q_cur = ggml_mul_mat_aux(ctx0, q_cur, k_rot);
         if (k_cur) {
-            k_cur = ggml_mul_mat_aux(ctx0, k_cur, inp->self_k_rot);
+            k_cur = ggml_mul_mat_aux(ctx0, k_cur, k_rot);
         }
     }
-    if (inp->self_v_rot) {
+    if (v_rot) {
         if (v_cur) {
-            v_cur = ggml_mul_mat_aux(ctx0, v_cur, inp->self_v_rot);
+            v_cur = ggml_mul_mat_aux(ctx0, v_cur, v_rot);
         }
     }
 
@@ -2259,8 +2280,6 @@ ggml_tensor * llm_graph_context::build_attn(
 
     const auto * mctx_iswa = inp->mctx;
 
-    const bool is_swa = hparams.is_swa(il);
-
     const auto * mctx_cur = is_swa ? mctx_iswa->get_swa() : mctx_iswa->get_base();
 
     // optionally store to KV cache
@@ -2285,8 +2304,8 @@ ggml_tensor * llm_graph_context::build_attn(
     ggml_tensor * cur = build_attn_mha(q, k, v, kq_b, kq_mask, sinks, v_mla, kq_scale, il);
     cb(cur, "kqv_out", il);
 
-    if (inp->self_v_rot) {
-        cur = ggml_mul_mat_aux(ctx0, cur, inp->self_v_rot);
+    if (v_rot) {
+        cur = ggml_mul_mat_aux(ctx0, cur, v_rot);
     }
 
     if (wo) {
@@ -2388,6 +2407,9 @@ llm_graph_input_attn_kv_iswa * llm_graph_context::build_attn_inp_kv_iswa() const
     inp->self_k_rot = mctx_cur->get_base()->build_input_k_rot(ctx0);
     inp->self_v_rot = mctx_cur->get_base()->build_input_v_rot(ctx0);
 
+    inp->self_k_rot_swa = mctx_cur->get_swa()->build_input_k_rot(ctx0);
+    inp->self_v_rot_swa = mctx_cur->get_swa()->build_input_v_rot(ctx0);
+
     return (llm_graph_input_attn_kv_iswa *) res->add_input(std::move(inp));
 }
 

src/llama-graph.h

@@ -308,7 +308,7 @@ public:
     ggml_tensor * self_kq_mask     = nullptr; // F32 [n_kv, n_batch/n_stream, 1, n_stream]
     ggml_tensor * self_kq_mask_cnv = nullptr; //     [n_kv, n_batch/n_stream, 1, n_stream]
 
-    // note: assumes v_rot^ == I
+    // note: assumes v_rot^2 == I
     ggml_tensor * self_k_rot = nullptr;
     ggml_tensor * self_v_rot = nullptr;
 
@@ -388,10 +388,12 @@ public:
     ggml_tensor * self_kq_mask_swa     = nullptr; // F32 [n_kv, n_batch/n_stream, 1, n_stream]
     ggml_tensor * self_kq_mask_swa_cnv = nullptr; //     [n_kv, n_batch/n_stream, 1, n_stream]
 
-    // note: using same rotation matrices for both base and swa cache
     ggml_tensor * self_k_rot = nullptr;
     ggml_tensor * self_v_rot = nullptr;
 
+    ggml_tensor * self_k_rot_swa = nullptr;
+    ggml_tensor * self_v_rot_swa = nullptr;
+
     const llama_hparams hparams;
     const llama_cparams cparams;
 

src/llama-kv-cache.cpp

@@ -169,6 +169,18 @@ llama_kv_cache::llama_kv_cache(
             continue;
         }
 
+        if (n_embd_head_k_all == 0) {
+            n_embd_head_k_all = (int32_t) hparams.n_embd_head_k(il);
+        } else if (n_embd_head_k_all > 0 && n_embd_head_k_all != (int32_t) hparams.n_embd_head_k(il)) {
+            n_embd_head_k_all = -1;
+        }
+
+        if (n_embd_head_v_all == 0) {
+            n_embd_head_v_all = (int32_t) hparams.n_embd_head_v(il);
+        } else if (n_embd_head_v_all > 0 && n_embd_head_v_all != (int32_t) hparams.n_embd_head_v(il)) {
+            n_embd_head_v_all = -1;
+        }
+
         // [TAG_V_CACHE_VARIABLE]
         const uint32_t n_embd_k_gqa =            hparams.n_embd_k_gqa(il);
         const uint32_t n_embd_v_gqa = !v_trans ? hparams.n_embd_v_gqa(il) : hparams.n_embd_v_gqa_max();
@@ -276,23 +288,23 @@ llama_kv_cache::llama_kv_cache(
 
     attn_rot_k =
         !attn_rot_disable &&
+        n_embd_head_k_all > 0 &&
         ggml_is_quantized(type_k) &&
-        !hparams.is_n_embd_k_gqa_variable() &&
         hparams.n_embd_head_k() % 64 == 0;
 
     attn_rot_v =
         !attn_rot_disable &&
+        n_embd_head_v_all > 0 &&
         ggml_is_quantized(type_v) &&
-        !hparams.is_n_embd_v_gqa_variable() &&
         hparams.n_embd_head_v() % 64 == 0;
 
-    LLAMA_LOG_INFO("%s: attn_rot_k = %d\n", __func__, attn_rot_k);
-    LLAMA_LOG_INFO("%s: attn_rot_v = %d\n", __func__, attn_rot_v);
+    LLAMA_LOG_INFO("%s: attn_rot_k = %d, n_embd_head_k_all = %d\n", __func__, attn_rot_k, n_embd_head_k_all);
+    LLAMA_LOG_INFO("%s: attn_rot_v = %d, n_embd_head_k_all = %d\n", __func__, attn_rot_v, n_embd_head_v_all);
 
     // pre-compute the haramard matrices and keep them in host memory
     // TODO: in the future, we can make copies in the backend buffers to avoid host -> device transfers
     if (attn_rot_k || attn_rot_v) {
-        for (int64_t n = 64; n <= std::max(hparams.n_embd_head_k(), hparams.n_embd_head_v()); n *= 2) {
+        for (int64_t n = 64; n <= std::max(n_embd_head_k_all, n_embd_head_v_all); n *= 2) {
             attn_rot_hadamard[n] = std::vector<float>(n*n);
 
             ggml_init_params params = {
@@ -1308,7 +1320,7 @@ ggml_tensor * llama_kv_cache::build_input_k_rot(ggml_context * ctx) const {
         // ref: https://github.com/ggml-org/llama.cpp/pull/21038#issuecomment-4141323088
         do {
             nrot *= 2;
-        } while (hparams.n_embd_head_k() % nrot == 0);
+        } while (n_embd_head_k_all % nrot == 0);
         nrot /= 2;
 
         res = ggml_new_tensor_2d(ctx, GGML_TYPE_F32, nrot, nrot);

src/llama-kv-cache.h

@@ -239,6 +239,11 @@ private:
     bool attn_rot_k = false;
     bool attn_rot_v = false;
 
+    // if all layers participating in the cache have constant head size, the value is stored here
+    // otherwise the value is -1
+    int32_t n_embd_head_k_all = 0;
+    int32_t n_embd_head_v_all = 0;
+
     // pre-computed hadamard martrices
     std::unordered_map<int64_t, std::vector<float>> attn_rot_hadamard;