Testing: Dynamic enablement/disablement of backends

src/amd_detail/backend.h

@@ -22,6 +22,13 @@ namespace hipFile {
 // write() system call. Mirrors kernel's MAX_RW_COUNT
 static const size_t MAX_RW_COUNT = 0x7ffff000;
 
+/// @brief Backend is not enabled
+struct BackendDisabled : public std::runtime_error {
+    BackendDisabled() : std::runtime_error("Backend is disabled")
+    {
+    }
+};
+
 struct Backend {
     virtual ~Backend() = default;
 

src/amd_detail/backend/fallback.cpp

@@ -8,6 +8,7 @@
 #include "buffer.h"
 #include "backend/asyncop-fallback.h"
 #include "backend/memcpy-kernel.h"
+#include "configuration.h"
 #include "context.h"
 #include "fallback.h"
 #include "file.h"
@@ -47,7 +48,8 @@ Fallback::score(std::shared_ptr<IFile> file, std::shared_ptr<IBuffer> buffer, si
     (void)file;
     (void)file_offset;
     (void)size;
-    return buffer->getType() == hipMemoryTypeDevice ? 0 : -1;
+
+    return Context<Configuration>::get()->fallback() && buffer->getType() == hipMemoryTypeDevice ? 0 : -1;
 }
 
 ssize_t
@@ -61,6 +63,10 @@ ssize_t
 Fallback::io(IoType io_type, shared_ptr<IFile> file, shared_ptr<IBuffer> buffer, size_t size,
              hoff_t file_offset, hoff_t buffer_offset, size_t chunk_size)
 {
+    if (!Context<Configuration>::get()->fallback()) {
+        throw BackendDisabled();
+    }
+
     size = min(size, hipFile::MAX_RW_COUNT);
 
     if (!paramsValid(buffer, size, file_offset, buffer_offset)) {

src/amd_detail/backend/fastpath.cpp

@@ -4,6 +4,7 @@
  */
 
 #include "buffer.h"
+#include "configuration.h"
 #include "context.h"
 #include "fastpath.h"
 #include "file.h"
@@ -128,6 +129,8 @@ Fastpath::score(shared_ptr<IFile> file, shared_ptr<IBuffer> buffer, size_t size,
 {
     bool accept_io{true};
 
+    accept_io &= Context<Configuration>::get()->fastpath();
+
     accept_io &= file->getUnbufferedFd().has_value();
 
     accept_io &= buffer->getType() == hipMemoryTypeDevice;
@@ -158,6 +161,10 @@ ssize_t
 Fastpath::io(IoType type, shared_ptr<IFile> file, shared_ptr<IBuffer> buffer, size_t size, hoff_t file_offset,
              hoff_t buffer_offset)
 {
+    if (!Context<Configuration>::get()->fastpath()) {
+        throw BackendDisabled();
+    }
+
     void *devptr{reinterpret_cast<void *>(reinterpret_cast<intptr_t>(buffer->getBuffer()) + buffer_offset)};
     hipAmdFileHandle_t handle{};
     size_t             nbytes{};

src/amd_detail/configuration.cpp

@@ -6,51 +6,43 @@
 #include "configuration.h"
 #include "environment.h"
 #include "hip.h"
+#include "static.h"
 
 #include <optional>
 
 using namespace hipFile;
 
-Configuration::Configuration() : m_fastpath(true), m_fallback(true), m_statsLevel(0)
+bool
+Configuration::fastpath() const noexcept
 {
-    auto maybe_env_force_compat{Environment::force_compat_mode()};
-    if (maybe_env_force_compat && maybe_env_force_compat.value()) {
-        m_fastpath = false;
-    }
-
-    auto maybe_env_allow_compat{Environment::allow_compat_mode()};
-    if (maybe_env_allow_compat && !maybe_env_allow_compat.value()) {
-        m_fallback = false;
-    }
-
-    auto maybe_stats_level{Environment::stats_level()};
-    if (maybe_stats_level) {
-        m_statsLevel = maybe_stats_level.value();
-    }
+    STATIC bool fastpath_env{!Environment::force_compat_mode().value_or(false)};
+    STATIC bool readExists{!!getHipAmdFileReadPtr()};
+    STATIC bool writeExists{!!getHipAmdFileWritePtr()};
+    return readExists && writeExists && m_fastpath_override.value_or(fastpath_env);
 }
 
-bool
-Configuration::fastpath() const noexcept
+void
+Configuration::fastpath(bool enabled) noexcept
 {
-#ifndef AIS_TESTING
-    static
-#endif
-        bool readExists{!!getHipAmdFileReadPtr()};
-#ifndef AIS_TESTING
-    static
-#endif
-        bool writeExists{!!getHipAmdFileWritePtr()};
-    return readExists && writeExists && m_fastpath;
+    m_fastpath_override = enabled;
 }
 
 bool
 Configuration::fallback() const noexcept
 {
-    return m_fallback;
+    STATIC bool fallback_env{Environment::allow_compat_mode().value_or(true)};
+    return m_fallback_override.value_or(fallback_env);
+}
+
+void
+Configuration::fallback(bool enabled) noexcept
+{
+    m_fallback_override = enabled;
 }
 
 unsigned int
 Configuration::statsLevel() const noexcept
 {
-    return m_statsLevel;
+    STATIC unsigned int stats_level_env{Environment::stats_level().value_or(0)};
+    return stats_level_env;
 }

src/amd_detail/configuration.h

@@ -5,38 +5,38 @@
 
 #pragma once
 
+#include <optional>
+
 namespace hipFile {
 
-class IConfiguration {
+class Configuration {
+
+    std::optional<bool> m_fastpath_override;
+    std::optional<bool> m_fallback_override;
+
 public:
-    virtual ~IConfiguration()
-    {
-    }
+    virtual ~Configuration() = default;
 
     /// @brief Checks if the fastpath backend is enabled
     /// @return true if the fastpath backend is enabled, false otherwise
-    virtual bool fastpath() const noexcept = 0;
+    virtual bool fastpath() const noexcept;
+
+    /// @brief Override fastpath backend enablement.
+    ///
+    /// If hipAmdFileRead/hipAmdFileWrite are not available fastpath() will
+    /// return false even if fastpath(true) is called.
+    virtual void fastpath(bool enabled) noexcept;
 
     /// @brief Checks if the fallback backend is enabled
     /// @return true if the fallback backend is enabled, false otherwise
-    virtual bool fallback() const noexcept = 0;
+    virtual bool fallback() const noexcept;
+
+    /// @brief Override fallback backend enablement
+    virtual void fallback(bool enabled) noexcept;
 
     /// @brief Shows the level of detail for stats collection
     /// @return 0 if stats collection disabled, higher levels of detail as value increases
-    virtual unsigned int statsLevel() const noexcept = 0;
-};
-
-class Configuration : public IConfiguration {
-    bool         m_fastpath;
-    bool         m_fallback;
-    unsigned int m_statsLevel;
-
-public:
-    Configuration();
-
-    bool         fastpath() const noexcept override;
-    bool         fallback() const noexcept override;
-    unsigned int statsLevel() const noexcept override;
+    virtual unsigned int statsLevel() const noexcept;
 };
 
 }

src/amd_detail/hip.cpp

@@ -5,6 +5,7 @@
 
 #include "context.h"
 #include "hip.h"
+#include "static.h"
 
 #include <cstdlib>
 #include <system_error>
@@ -24,22 +25,16 @@ catch (...) {
 hipAmdFileRead_t
 getHipAmdFileReadPtr()
 {
-#ifndef AIS_TESTING
-    static
-#endif
-        hipAmdFileRead_t hipAmdFileReadPtr{
-            reinterpret_cast<hipAmdFileRead_t>(hipGetProcAddressHelper("hipAmdFileRead"))};
+    STATIC hipAmdFileRead_t hipAmdFileReadPtr{
+        reinterpret_cast<hipAmdFileRead_t>(hipGetProcAddressHelper("hipAmdFileRead"))};
     return hipAmdFileReadPtr;
 }
 
 hipAmdFileWrite_t
 getHipAmdFileWritePtr()
 {
-#ifndef AIS_TESTING
-    static
-#endif
-        hipAmdFileWrite_t hipAmdFileWritePtr{
-            reinterpret_cast<hipAmdFileWrite_t>(hipGetProcAddressHelper("hipAmdFileWrite"))};
+    STATIC hipAmdFileWrite_t hipAmdFileWritePtr{
+        reinterpret_cast<hipAmdFileWrite_t>(hipGetProcAddressHelper("hipAmdFileWrite"))};
     return hipAmdFileWritePtr;
 }
 

src/amd_detail/state.cpp

@@ -275,12 +275,8 @@ std::vector<std::shared_ptr<Backend>>
 DriverState::getBackends() const
 {
     static bool once = [&]() {
-        if (Context<Configuration>::get()->fastpath()) {
-            backends.emplace_back(new Fastpath{});
-        }
-        if (Context<Configuration>::get()->fallback()) {
-            backends.emplace_back(new Fallback{});
-        }
+        backends.emplace_back(new Fastpath{});
+        backends.emplace_back(new Fallback{});
         return true;
     }();
     (void)once;

src/amd_detail/static.h

@@ -0,0 +1,15 @@
+/* Copyright (c) Advanced Micro Devices, Inc. All rights reserved.
+ *
+ * SPDX-License-Identifier: MIT
+ */
+
+#pragma once
+
+// When testing it is sometimes inconvenient if a variable is statically initialized.
+// Declaring a variable as STATIC will result in the variable being static only
+// when tests are not being built.
+#ifdef AIS_TESTING
+#define STATIC
+#else
+#define STATIC static
+#endif

test/CMakeLists.txt

@@ -24,7 +24,6 @@ set(SYSTEM_TEST_SOURCE_FILES
     system/buffer.cpp
     system/config.cpp
     system/driver.cpp
-    system/io.cpp
     system/main.cpp
     system/version.cpp
 )
@@ -38,6 +37,7 @@ if(AIS_BUILD_NVIDIA_DETAIL)
     list(APPEND UNIT_TEST_SOURCE_FILES nvidia_detail/cufile-api-compat.cpp)
     list(APPEND TEST_SYSINCLS ${HIPFILE_NVIDIA_SOURCE_PATH})
 else()
+    list(APPEND SYSTEM_TEST_SOURCE_FILES system/amd/io.cpp)
     list(APPEND TEST_SYSINCLS ${HIPFILE_AMD_SOURCE_PATH})
 endif()