GH-128842: Collect JIT memory stats (GH-128941)

Author: diegorusso

Include/cpython/pystats.h

@@ -141,6 +141,14 @@ typedef struct _optimization_stats {
     uint64_t remove_globals_builtins_changed;
     uint64_t remove_globals_incorrect_keys;
     uint64_t error_in_opcode[PYSTATS_MAX_UOP_ID + 1];
+    // JIT memory stats
+    uint64_t jit_total_memory_size;
+    uint64_t jit_code_size;
+    uint64_t jit_trampoline_size;
+    uint64_t jit_data_size;
+    uint64_t jit_padding_size;
+    uint64_t jit_freed_memory_size;
+    uint64_t trace_total_memory_hist[_Py_UOP_HIST_SIZE];
 } OptimizationStats;
 
 typedef struct _rare_event_stats {

Include/internal/pycore_code.h

@@ -373,6 +373,7 @@ extern void _Py_Specialize_ContainsOp(_PyStackRef value, _Py_CODEUNIT *instr);
     do { if (_Py_stats && PyFunction_Check(callable)) _Py_stats->call_stats.eval_calls[name]++; } while (0)
 #define GC_STAT_ADD(gen, name, n) do { if (_Py_stats) _Py_stats->gc_stats[(gen)].name += (n); } while (0)
 #define OPT_STAT_INC(name) do { if (_Py_stats) _Py_stats->optimization_stats.name++; } while (0)
+#define OPT_STAT_ADD(name, n) do { if (_Py_stats) _Py_stats->optimization_stats.name += (n); } while (0)
 #define UOP_STAT_INC(opname, name) do { if (_Py_stats) { assert(opname < 512); _Py_stats->optimization_stats.opcode[opname].name++; } } while (0)
 #define UOP_PAIR_INC(uopcode, lastuop)                                              \
     do {                                                                            \
@@ -408,6 +409,7 @@ PyAPI_FUNC(PyObject*) _Py_GetSpecializationStats(void);
 #define EVAL_CALL_STAT_INC_IF_FUNCTION(name, callable) ((void)0)
 #define GC_STAT_ADD(gen, name, n) ((void)0)
 #define OPT_STAT_INC(name) ((void)0)
+#define OPT_STAT_ADD(name, n) ((void)0)
 #define UOP_STAT_INC(opname, name) ((void)0)
 #define UOP_PAIR_INC(uopcode, lastuop) ((void)0)
 #define OPT_UNSUPPORTED_OPCODE(opname) ((void)0)

Misc/NEWS.d/next/Core_and_Builtins/2025-01-17-13-16-14.gh-issue-128842.OMs5X6.rst

@@ -0,0 +1 @@
+Collect JIT memory stats using pystats. Patch by Diego Russo.

Python/jit.c

@@ -87,6 +87,7 @@ jit_free(unsigned char *memory, size_t size)
         jit_error("unable to free memory");
         return -1;
     }
+    OPT_STAT_ADD(jit_freed_memory_size, size);
     return 0;
 }
 
@@ -510,6 +511,13 @@ _PyJIT_Compile(_PyExecutorObject *executor, const _PyUOpInstruction trace[], siz
 #ifdef MAP_JIT
     pthread_jit_write_protect_np(0);
 #endif
+    // Collect memory stats
+    OPT_STAT_ADD(jit_total_memory_size, total_size);
+    OPT_STAT_ADD(jit_code_size, code_size);
+    OPT_STAT_ADD(jit_trampoline_size, state.trampolines.size);
+    OPT_STAT_ADD(jit_data_size, data_size);
+    OPT_STAT_ADD(jit_padding_size, padding);
+    OPT_HIST(total_size, trace_total_memory_hist);
     // Update the offsets of each instruction:
     for (size_t i = 0; i < length; i++) {
         state.instruction_starts[i] += (uintptr_t)memory;

Python/specialize.c

@@ -309,6 +309,14 @@ print_optimization_stats(FILE *out, OptimizationStats *stats)
             );
         }
     }
+    fprintf(out, "JIT total memory size: %" PRIu64 "\n", stats->jit_total_memory_size);
+    fprintf(out, "JIT code size: %" PRIu64 "\n", stats->jit_code_size);
+    fprintf(out, "JIT trampoline size: %" PRIu64 "\n", stats->jit_trampoline_size);
+    fprintf(out, "JIT data size: %" PRIu64 "\n", stats->jit_data_size);
+    fprintf(out, "JIT padding size: %" PRIu64 "\n", stats->jit_padding_size);
+    fprintf(out, "JIT freed memory size: %" PRIu64 "\n", stats->jit_freed_memory_size);
+
+    print_histogram(out, "Trace total memory size", stats->trace_total_memory_hist);
 }
 #endif
 

Tools/scripts/summarize_stats.py

@@ -545,6 +545,41 @@ def get_optimizer_stats(self) -> dict[str, tuple[int, int | None]]:
             ): (incorrect_keys, attempts),
         }
 
+    def get_jit_memory_stats(self) -> dict[Doc, tuple[int, int | None]]:
+        jit_total_memory_size = self._data["JIT total memory size"]
+        jit_code_size = self._data["JIT code size"]
+        jit_trampoline_size = self._data["JIT trampoline size"]
+        jit_data_size = self._data["JIT data size"]
+        jit_padding_size = self._data["JIT padding size"]
+        jit_freed_memory_size = self._data["JIT freed memory size"]
+
+        return {
+            Doc(
+                "Total memory size",
+                "The total size of the memory allocated for the JIT traces",
+            ): (jit_total_memory_size, None),
+            Doc(
+                "Code size",
+                "The size of the memory allocated for the code of the JIT traces",
+            ): (jit_code_size, jit_total_memory_size),
+            Doc(
+                "Trampoline size",
+                "The size of the memory allocated for the trampolines of the JIT traces",
+            ): (jit_trampoline_size, jit_total_memory_size),
+            Doc(
+                "Data size",
+                "The size of the memory allocated for the data of the JIT traces",
+            ): (jit_data_size, jit_total_memory_size),
+            Doc(
+                "Padding size",
+                "The size of the memory allocated for the padding of the JIT traces",
+            ): (jit_padding_size, jit_total_memory_size),
+            Doc(
+                "Freed memory size",
+                "The size of the memory freed from the JIT traces",
+            ): (jit_freed_memory_size, jit_total_memory_size),
+        }
+
     def get_histogram(self, prefix: str) -> list[tuple[int, int]]:
         rows = []
         for k, v in self._data.items():
@@ -1161,26 +1196,51 @@ def calc_optimizer_table(stats: Stats) -> Rows:
             for label, (value, den) in optimizer_stats.items()
         ]
 
-    def calc_histogram_table(key: str, den: str) -> RowCalculator:
+    def calc_jit_memory_table(stats: Stats) -> Rows:
+        jit_memory_stats = stats.get_jit_memory_stats()
+
+        return [
+            (
+                label,
+                Count(value),
+                Ratio(value, den, percentage=label != "Total memory size"),
+            )
+            for label, (value, den) in jit_memory_stats.items()
+        ]
+
+    def calc_histogram_table(key: str, den: str | None = None) -> RowCalculator:
         def calc(stats: Stats) -> Rows:
             histogram = stats.get_histogram(key)
-            denominator = stats.get(den)
+
+            if den:
+                denominator = stats.get(den)
+            else:
+                denominator = 0
+                for _, v in histogram:
+                    denominator += v
 
             rows: Rows = []
-            last_non_zero = 0
             for k, v in histogram:
-                if v != 0:
-                    last_non_zero = len(rows)
                 rows.append(
                     (
                         f"<= {k:,d}",
                         Count(v),
                         Ratio(v, denominator),
                     )
                 )
-            # Don't include any zero entries at the end
-            rows = rows[: last_non_zero + 1]
-            return rows
+            # Don't include any leading and trailing zero entries
+            start = 0
+            end = len(rows) - 1
+
+            while start <= end:
+                if rows[start][1] == 0:
+                    start += 1
+                elif rows[end][1] == 0:
+                    end -= 1
+                else:
+                    break
+
+            return rows[start:end+1]
 
         return calc
 
@@ -1214,6 +1274,28 @@ def iter_optimization_tables(base_stats: Stats, head_stats: Stats | None = None)
 
         yield Table(("", "Count:", "Ratio:"), calc_optimization_table, JoinMode.CHANGE)
         yield Table(("", "Count:", "Ratio:"), calc_optimizer_table, JoinMode.CHANGE)
+        yield Section(
+            "JIT memory stats",
+            "JIT memory stats",
+            [
+                Table(
+                    ("", "Size (bytes):", "Ratio:"),
+                    calc_jit_memory_table,
+                    JoinMode.CHANGE
+                )
+            ],
+        )
+        yield Section(
+            "JIT trace total memory histogram",
+            "JIT trace total memory histogram",
+            [
+                Table(
+                    ("Size (bytes)", "Count", "Ratio:"),
+                    calc_histogram_table("Trace total memory size"),
+                    JoinMode.CHANGE_NO_SORT,
+                )
+            ],
+        )
         for name, den in [
             ("Trace length", "Optimization traces created"),
             ("Optimized trace length", "Optimization traces created"),