Re: [RFC PATCH 2/6] accel/tcg: Avoid uncessary call overhead from qemu_plugin_vcpu_mem_cb

[Daniel Henrique Barboza]

On 2/15/24 16:28, Max Chou wrote:

If there are not any QEMU plugin memory callback functions, checking
before calling the qemu_plugin_vcpu_mem_cb function can reduce the
function call overhead.

Signed-off-by: Max Chou <max.c...@sifive.com>
---

This was in my TODO list for some time. Thanks for looking it up.

Can't we avoid all callbacks, not just qemu_plugin_vcpu_mem_cb, if there's no
plugin loaded? The performance increase when building with --disable-plugins
shouldn't be a thing - if the user isn't using plug-ins it should have a
penalty to it.

Thanks,

Daniel

  accel/tcg/ldst_common.c.inc | 40 +++++++++++++++++++++++++++----------
  1 file changed, 30 insertions(+), 10 deletions(-)

diff --git a/accel/tcg/ldst_common.c.inc b/accel/tcg/ldst_common.c.inc
index c82048e377e..bf24986c562 100644
--- a/accel/tcg/ldst_common.c.inc
+++ b/accel/tcg/ldst_common.c.inc
@@ -134,7 +134,9 @@ uint8_t cpu_ldb_mmu(CPUArchState *env, abi_ptr addr, 
MemOpIdx oi, uintptr_t ra)

tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_UB);

      ret = do_ld1_mmu(env_cpu(env), addr, oi, ra, MMU_DATA_LOAD);
-    plugin_load_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_load_cb(env, addr, oi);
+    }
      return ret;
  }

@@ -145,7 +147,9 @@ uint16_t cpu_ldw_mmu(CPUArchState *env, abi_ptr addr, tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_16);

      ret = do_ld2_mmu(env_cpu(env), addr, oi, ra, MMU_DATA_LOAD);
-    plugin_load_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_load_cb(env, addr, oi);
+    }
      return ret;
  }

@@ -156,7 +160,9 @@ uint32_t cpu_ldl_mmu(CPUArchState *env, abi_ptr addr, tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_32);

      ret = do_ld4_mmu(env_cpu(env), addr, oi, ra, MMU_DATA_LOAD);
-    plugin_load_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_load_cb(env, addr, oi);
+    }
      return ret;
  }

@@ -167,7 +173,9 @@ uint64_t cpu_ldq_mmu(CPUArchState *env, abi_ptr addr, tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_64);

      ret = do_ld8_mmu(env_cpu(env), addr, oi, ra, MMU_DATA_LOAD);
-    plugin_load_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_load_cb(env, addr, oi);
+    }
      return ret;
  }

@@ -178,7 +186,9 @@ Int128 cpu_ld16_mmu(CPUArchState *env, abi_ptr addr, tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_128);

      ret = do_ld16_mmu(env_cpu(env), addr, oi, ra);
-    plugin_load_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_load_cb(env, addr, oi);
+    }
      return ret;
  }

@@ -195,7 +205,9 @@ void cpu_stb_mmu(CPUArchState *env, abi_ptr addr, uint8_t val,

                   MemOpIdx oi, uintptr_t retaddr)
  {
      helper_stb_mmu(env, addr, val, oi, retaddr);
-    plugin_store_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_store_cb(env, addr, oi);
+    }
  }

void cpu_stw_mmu(CPUArchState *env, abi_ptr addr, uint16_t val,

@@ -203,7 +215,9 @@ void cpu_stw_mmu(CPUArchState *env, abi_ptr addr, uint16_t 
val,
  {
      tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_16);
      do_st2_mmu(env_cpu(env), addr, val, oi, retaddr);
-    plugin_store_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_store_cb(env, addr, oi);
+    }
  }

void cpu_stl_mmu(CPUArchState *env, abi_ptr addr, uint32_t val,

@@ -211,7 +225,9 @@ void cpu_stl_mmu(CPUArchState *env, abi_ptr addr, uint32_t 
val,
  {
      tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_32);
      do_st4_mmu(env_cpu(env), addr, val, oi, retaddr);
-    plugin_store_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_store_cb(env, addr, oi);
+    }
  }

void cpu_stq_mmu(CPUArchState *env, abi_ptr addr, uint64_t val,

@@ -219,7 +235,9 @@ void cpu_stq_mmu(CPUArchState *env, abi_ptr addr, uint64_t 
val,
  {
      tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_64);
      do_st8_mmu(env_cpu(env), addr, val, oi, retaddr);
-    plugin_store_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_store_cb(env, addr, oi);
+    }
  }

void cpu_st16_mmu(CPUArchState *env, abi_ptr addr, Int128 val,

@@ -227,7 +245,9 @@ void cpu_st16_mmu(CPUArchState *env, abi_ptr addr, Int128 
val,
  {
      tcg_debug_assert((get_memop(oi) & MO_SIZE) == MO_128);
      do_st16_mmu(env_cpu(env), addr, val, oi, retaddr);
-    plugin_store_cb(env, addr, oi);
+    if (cpu_plugin_mem_cbs_enabled(env_cpu(env))) {
+        plugin_store_cb(env, addr, oi);
+    }
  }

/*