Windbg Extension improvments

- Add settings command
- Fix help
- Fix Arenas

CMakeLists.txt

@@ -295,6 +295,7 @@ if(WIN32 AND MI_WIN_DBG_EXTS)
   list(APPEND mi_sources ${PROJECT_SOURCE_DIR}/src/prim/windows/windbg/mimalloc_windbg_arenas.cpp)
   list(APPEND mi_sources ${PROJECT_SOURCE_DIR}/src/prim/windows/windbg/mimalloc_windbg_help.cpp)
   list(APPEND mi_sources ${PROJECT_SOURCE_DIR}/src/prim/windows/windbg/mimalloc_windbg_options.cpp)
+  list(APPEND mi_sources ${PROJECT_SOURCE_DIR}/src/prim/windows/windbg/mimalloc_windbg_settings.cpp)
   list(APPEND mi_sources ${PROJECT_SOURCE_DIR}/src/prim/windows/windbg/mimalloc_windbg_stats.cpp)
   list(APPEND mi_sources ${PROJECT_SOURCE_DIR}/src/prim/windows/windbg/mimalloc_windbg_utils.cpp)
   list(APPEND mi_sources ${PROJECT_SOURCE_DIR}/src/prim/windows/windbg/mimalloc_windbg.cpp)

src/prim/windows/windbg/mimalloc_windbg.cpp

@@ -79,6 +79,7 @@ extern "C" __declspec(dllexport) HRESULT CALLBACK DebugExtensionInitialize(PULON
     g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_dump_options\">Dump Options</link>\n");
     g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_dump_arenas\">Dump Arenas</link>\n");
     g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_dump_stats\">Dump Statistics</link>\n");
+    g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_show_extension_settings\">Show Extension Settings</link>\n");
     g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_show_help\">Show Help commands</link>\n");
     g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
 

src/prim/windows/windbg/mimalloc_windbg_arenas.cpp

@@ -7,6 +7,30 @@ terms of the MIT license. A copy of the license can be found in the file
 
 #include "mimalloc_windbg_utils.h"
 
+void PrintArenaSummary(double totalSlices, double totalCommittedSlices, double totalCommittedPages, double totalAbandonedPages) {
+    double pctCommitted = (totalSlices > 0) ? (totalCommittedSlices * 100.0 / totalSlices) : 0.0;
+    const auto arenaStats = std::format(" Total Slices: {}\n Committed Slices: {} ({}%)", totalSlices, totalCommittedSlices, pctCommitted);
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\nAggregated Arena Statistics:\n%s\n", arenaStats.c_str());
+
+    const auto pageStats = std::format(" Committed Pages: {}\n Abandoned Pages: {}", totalCommittedPages, totalAbandonedPages);
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\nAggregated Page Statistics:\n%s\n", pageStats.c_str());
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
+}
+
+void PrintAnomalyDetectionIfNeeded(double potentialFragmentation, double highAbandonedPagesRatio) {
+    if (potentialFragmentation < MinCommittedSlicesPct) {
+        g_DebugControl->Output(DEBUG_OUTPUT_ERROR, " Warning: Low committed slices percentage (%.2f%%). Potential fragmentation detected.\n", potentialFragmentation);
+    }
+
+    if (highAbandonedPagesRatio > MaxAbandonedPagesRatio) {
+        g_DebugControl->Output(DEBUG_OUTPUT_ERROR, " Warning: High ratio of abandoned pages (%.2f%%). Possible memory leak or delayed decommitment.\n", highAbandonedPagesRatio);
+    }
+
+    if (potentialFragmentation < MinCommittedSlicesPct || highAbandonedPagesRatio > MaxAbandonedPagesRatio) {
+        g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
+    }
+}
+
 /*
 Command: !mi_dump_arenas
     - Arenas are a fundamental component of mimalloc’s memory management.
@@ -115,30 +139,13 @@ extern "C" __declspec(dllexport) HRESULT CALLBACK mi_dump_arenas(PDEBUG_CLIENT c
     g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\nTotal Arenas: %d\n", arenaCount);
 
     // Summary that aids in detecting fragmentation or undercommitment.
-    double pctCommitted = (totalSlices > 0) ? (totalCommittedSlices * 100.0 / totalSlices) : 0.0;
+    PrintArenaSummary(totalSlices, totalCommittedSlices, totalCommittedPages, totalAbandonedPages);
-    const auto arenaStats = std::format(" Total Slices: {}\n Committed Slices: {} ({}%)", totalSlices, totalCommittedSlices, pctCommitted);
-    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\nAggregated Arena Statistics:\n%s\n", arenaStats.c_str());
-
-    const auto pageStats = std::format(" Committed Pages: {}\n Abandoned Pages: {}", totalCommittedPages, totalAbandonedPages);
-    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\nAggregated Page Statistics:\n%s\n", pageStats.c_str());
-    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
 
     for (size_t i = 0; i < arenaCount; ++i) {
         ULONG64 arenaAddr = subprocMainAddr + offsetof(mi_subproc_t, arenas) + (i * sizeof(std::atomic<mi_arena_t*>));
         PrintLink(arenaAddr, std::format("!mi_dump_arena 0x{:016X}", arenaAddr), std::format("Arena {}", i));
 
-        if (potentialFragmentation[i] < MinCommittedSlicesPct) {
+        PrintAnomalyDetectionIfNeeded(potentialFragmentation[i], highAbandonedPagesRatio[i]);
-            g_DebugControl->Output(DEBUG_OUTPUT_ERROR, " Warning: Low committed slices percentage (%.2f%%). Potential fragmentation detected.\n", potentialFragmentation[i]);
-        }
-
-        if (highAbandonedPagesRatio[i] > MaxAbandonedPagesRatio) {
-            g_DebugControl->Output(DEBUG_OUTPUT_ERROR, " Warning: High ratio of abandoned pages (%.2f%%). Possible memory leak or delayed decommitment.\n",
-                                   highAbandonedPagesRatio[i]);
-        }
-
-        if (potentialFragmentation[i] < MinCommittedSlicesPct || highAbandonedPagesRatio[i] > MaxAbandonedPagesRatio) {
-            g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
-        }
     }
 
     g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
@@ -235,13 +242,7 @@ extern "C" __declspec(dllexport) HRESULT CALLBACK mi_dump_arena(PDEBUG_CLIENT cl
     totalAbandonedPages += abandonedPages;
 
     // Summary that aids in detecting fragmentation or undercommitment.
-    double pctCommitted = (totalSlices > 0) ? (totalCommittedSlices * 100.0 / totalSlices) : 0.0;
+    PrintArenaSummary(totalSlices, totalCommittedSlices, totalCommittedPages, totalAbandonedPages);
-    const auto arenaStats = std::format(" Total Slices: {}\n Committed Slices: {} ({}%)", totalSlices, totalCommittedSlices, pctCommitted);
-    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\nAggregated Arena Statistics:\n%s\n", arenaStats.c_str());
-
-    const auto pageStats = std::format(" Committed Pages: {}\n Abandoned Pages: {}", totalCommittedPages, totalAbandonedPages);
-    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\nAggregated Page Statistics:\n%s\n", pageStats.c_str());
-    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
 
     // --- Anomaly Detection ---
     float pctCommittedSlices = (arena.slice_count > 0) ? (committed * 100.0 / arena.slice_count) : 0.0;
@@ -251,14 +252,8 @@ extern "C" __declspec(dllexport) HRESULT CALLBACK mi_dump_arena(PDEBUG_CLIENT cl
         abandonedPagesRatio = (abandonedPages * 100.0) / committedPages;
     }
 
-    if (pctCommittedSlices < MinCommittedSlicesPct) {
+    PrintAnomalyDetectionIfNeeded(pctCommittedSlices, abandonedPagesRatio);
-        g_DebugControl->Output(DEBUG_OUTPUT_ERROR, " Warning: Low committed slices percentage (%.2f%%). Potential fragmentation detected.\n", pctCommittedSlices);
-    }
-
-    if (abandonedPagesRatio > MaxAbandonedPagesRatio) {
-        g_DebugControl->Output(DEBUG_OUTPUT_ERROR, " Warning: High ratio of abandoned pages (%.2f%%). Possible memory leak or delayed decommitment.\n", abandonedPagesRatio);
-    }
 
     g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
     return S_OK;
-}
+}

src/prim/windows/windbg/mimalloc_windbg_help.cpp

@@ -15,9 +15,17 @@ extern "C" __declspec(dllexport) HRESULT CALLBACK mi_show_help(PDEBUG_CLIENT cli
 
     HRESULT hr = S_OK;
 
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
+
     // Print Help
     g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "Hello from MiMalloc WinDbg Extension!\n");
     g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "Start here:\n");
+    g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_dump_options\">Dump Options</link>\n");
+    g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_dump_arenas\">Dump Arenas</link>\n");
+    g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_dump_stats\">Dump Statistics</link>\n");
+    g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_show_extension_settings\">Show Extension Settings</link>\n");
+    g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL, "<link cmd=\"!mi_show_help\">Show Help commands</link>\n");
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
 
     return S_OK;
 }

src/prim/windows/windbg/mimalloc_windbg_settings.cpp

@@ -0,0 +1,83 @@
+/* ----------------------------------------------------------------------------
+Copyright (c) Microsoft Research
+This is free software; you can redistribute it and/or modify it under the
+terms of the MIT license. A copy of the license can be found in the file
+"LICENSE" at the root of this distribution.
+-----------------------------------------------------------------------------*/
+
+#include "mimalloc_windbg_utils.h"
+
+/*
+Command: !mi_show_extension_settings
+*/
+extern "C" __declspec(dllexport) HRESULT CALLBACK mi_show_extension_settings(PDEBUG_CLIENT client, PCSTR args) {
+    UNREFERENCED_PARAMETER(args);
+
+    HRESULT hr = S_OK;
+
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
+
+    g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL,
+                                     std::format("{:<30} {:<10} {}\n", "MinCommittedSlicesPct", MinCommittedSlicesPct, "When below threshold, potential fragmentation.").c_str());
+
+    g_DebugControl->ControlledOutput(
+        DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL,
+        std::format("{:<30} {:<10} {}\n", "MaxAbandonedPagesRatio", MaxAbandonedPagesRatio, "When abandoned pages exceeds ratio of committed pages, potential leak.").c_str());
+
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
+
+    g_DebugControl->ControlledOutput(DEBUG_OUTCTL_AMBIENT_DML, DEBUG_OUTPUT_NORMAL,
+                                     "Use <b>!mi_set_extension_setting &lt;setting&gt; &lt;value&gt;</b> to set a new value for the setting.\n");
+
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
+
+    return S_OK;
+}
+
+/*
+Command: !mi_set_extension_setting
+*/
+extern "C" __declspec(dllexport) HRESULT CALLBACK mi_set_extension_setting(PDEBUG_CLIENT client, PCSTR args) {
+    if (!args || !*args) {
+        g_DebugControl->Output(DEBUG_OUTPUT_ERROR, "Usage: !mi_set_extension_setting <setting> <value>\n");
+        return E_INVALIDARG;
+    }
+
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "\n");
+
+    char fieldName[64];
+    char valueStr[64];
+
+    // Parse the input arguments
+    if (sscanf_s(args, "%63s %63s", fieldName, (unsigned)_countof(fieldName), valueStr, (unsigned)_countof(valueStr)) != 2) {
+        g_DebugControl->Output(DEBUG_OUTPUT_ERROR, "ERROR: Invalid input format. Expected: !mi_set_extension_setting <setting> <value>\n");
+        return E_INVALIDARG;
+    }
+
+    HRESULT hr = S_OK;
+
+    // Update the setting based on the field name
+    if (strcmp(fieldName, "MinCommittedSlicesPct") == 0) {
+        double doubleValue = 0.0;
+        if (sscanf_s(valueStr, "%lf", &doubleValue) != 1 || doubleValue < 0 || doubleValue > 100) {
+            g_DebugControl->Output(DEBUG_OUTPUT_ERROR, "ERROR: Value must be an value between 0 and 100.\n");
+            return E_INVALIDARG;
+        }
+
+        MinCommittedSlicesPct = doubleValue;
+    } else if (strcmp(fieldName, "MaxAbandonedPagesRatio") == 0) {
+        double doubleValue = 0.0;
+        if (sscanf_s(valueStr, "%lf", &doubleValue) != 1 || doubleValue < 0.0 || doubleValue > 1.0) {
+            g_DebugControl->Output(DEBUG_OUTPUT_ERROR, "ERROR: Value must be a value between 0.0 and 1.0.\n");
+            return E_INVALIDARG;
+        }
+
+        MaxAbandonedPagesRatio = doubleValue;
+    } else {
+        g_DebugControl->Output(DEBUG_OUTPUT_ERROR, "ERROR: Invalid field name. Allowed fields: MinCommittedSlicesPct, MaxAbandonedPagesRatio\n");
+        return E_INVALIDARG;
+    }
+
+    g_DebugControl->Output(DEBUG_OUTPUT_NORMAL, "Successfully updated %s to %s\n", fieldName, valueStr);
+    return S_OK;
+}

src/prim/windows/windbg/mimalloc_windbg_utils.h

@@ -25,8 +25,8 @@ extern IDebugControl4* g_DebugControl;
 extern IDebugSymbols3* g_DebugSymbols;
 extern IDebugDataSpaces* g_DataSpaces;
 
-constexpr double MinCommittedSlicesPct = 60.0; // if below threshold, potential fragmentation.
+static inline double MinCommittedSlicesPct = 60.0; // if below threshold, potential fragmentation.
-constexpr double MaxAbandonedPagesRatio = 0.4; // If abandoned pages exceed 40% of committed pages.
+static inline double MaxAbandonedPagesRatio = 0.4; // If abandoned pages exceed 40% of committed pages.
 
 HRESULT FindMimallocBase();
 HRESULT GetSymbolOffset(const char* symbolName, ULONG64& outOffset);