Add debug key for limitting hw threads

Change-Id: I5770b9b0ecdfb98d96265b76b8a6404cc4abfa4c

Author: jchodor

opencl/test/unit_test/test_files/igdrcl.config

@@ -150,3 +150,5 @@ UseMaxSimdSizeToDeduceMaxWorkgroupSize = 0
 ReturnRawGpuTimestamps = 0
 ForcePerDssBackedBufferProgramming = 0
 DisableAtomicForPostSyncs = 0
+MaxHwThreadsPercent = 0
+MinHwThreadsUnoccupied = 0

shared/source/debug_settings/debug_variables_base.inl

@@ -110,6 +110,8 @@ DECLARE_DEBUG_VARIABLE(bool, DisableZeroCopyForUseHostPtr, false, "When active a
 DECLARE_DEBUG_VARIABLE(bool, DisableZeroCopyForBuffers, false, "When active all buffer allocations will not share memory with CPU.")
 DECLARE_DEBUG_VARIABLE(bool, DisableDcFlushInEpilogue, false, "Disable DC flush in epilogue")
 DECLARE_DEBUG_VARIABLE(int32_t, EnableHostPtrTracking, -1, "Enable host ptr tracking: -1 - default platform setting, 0 - disabled, 1 - enabled")
+DECLARE_DEBUG_VARIABLE(int32_t, MaxHwThreadsPercent, 0, "If not zero then maximum number of used HW threads is capped to max * MaxHwThreadsPercent / 100")
+DECLARE_DEBUG_VARIABLE(int32_t, MinHwThreadsUnoccupied, 0, "If not zero then maximum number of used HW threads is reduced by MinHwThreadsUnoccupied")
 
 /*FEATURE FLAGS*/
 DECLARE_DEBUG_VARIABLE(bool, EnableNV12, true, "Enables NV12 extension")

shared/source/helpers/hw_helper.cpp

@@ -42,7 +42,15 @@ bool HwHelper::cacheFlushAfterWalkerSupported(const HardwareInfo &hwInfo) {
 
 uint32_t HwHelper::getMaxThreadsForVfe(const HardwareInfo &hwInfo) {
     uint32_t threadsPerEU = (hwInfo.gtSystemInfo.ThreadCount / hwInfo.gtSystemInfo.EUCount) + hwInfo.capabilityTable.extraQuantityThreadsPerEU;
-    return hwInfo.gtSystemInfo.EUCount * threadsPerEU;
+    auto maxHwThreadsCapable = hwInfo.gtSystemInfo.EUCount * threadsPerEU;
+    auto maxHwThreadsReturned = maxHwThreadsCapable;
+    if (DebugManager.flags.MaxHwThreadsPercent.get() != 0) {
+        maxHwThreadsReturned = int(maxHwThreadsCapable * (DebugManager.flags.MaxHwThreadsPercent.get() / 100.0f));
+    }
+    if (DebugManager.flags.MinHwThreadsUnoccupied.get() != 0) {
+        maxHwThreadsReturned = std::min(maxHwThreadsReturned, maxHwThreadsCapable - DebugManager.flags.MinHwThreadsUnoccupied.get());
+    }
+    return maxHwThreadsReturned;
 }
 
 uint32_t HwHelper::getMaxThreadsForWorkgroup(const HardwareInfo &hwInfo, uint32_t maxNumEUsPerSubSlice) const {

shared/test/unit_test/preamble/preamble_tests.cpp

@@ -6,6 +6,7 @@
  */
 
 #include "shared/source/command_stream/preemption.h"
+#include "shared/source/debug_settings/debug_settings_manager.h"
 #include "shared/source/gen_common/reg_configs/reg_configs_common.h"
 #include "shared/source/helpers/flat_batch_buffer_helper_hw.h"
 #include "shared/source/helpers/preamble.h"
@@ -191,6 +192,28 @@ HWTEST_F(PreambleTest, givenDefaultPreambleWhenGetThreadsMaxNumberIsCalledThenMa
     EXPECT_EQ(expected, value);
 }
 
+HWTEST_F(PreambleTest, givenMaxHwThreadsPercentDebugVariableWhenGetThreadsMaxNumberIsCalledThenMaximumNumberOfThreadsIsCappedToRequestedNumber) {
+    const HardwareInfo &hwInfo = *defaultHwInfo;
+    uint32_t threadsPerEU = (hwInfo.gtSystemInfo.ThreadCount / hwInfo.gtSystemInfo.EUCount) + hwInfo.capabilityTable.extraQuantityThreadsPerEU;
+    DebugManagerStateRestore debugManagerStateRestore;
+    DebugManager.flags.MaxHwThreadsPercent.set(80);
+    uint32_t value = HwHelper::getMaxThreadsForVfe(hwInfo);
+
+    uint32_t expected = int(hwInfo.gtSystemInfo.EUCount * threadsPerEU * 80 / 100.0f);
+    EXPECT_EQ(expected, value);
+}
+
+HWTEST_F(PreambleTest, givenMinHwThreadsUnoccupiedDebugVariableWhenGetThreadsMaxNumberIsCalledThenMaximumNumberOfThreadsIsCappedToMatchRequestedNumber) {
+    const HardwareInfo &hwInfo = *defaultHwInfo;
+    uint32_t threadsPerEU = (hwInfo.gtSystemInfo.ThreadCount / hwInfo.gtSystemInfo.EUCount) + hwInfo.capabilityTable.extraQuantityThreadsPerEU;
+    DebugManagerStateRestore debugManagerStateRestore;
+    DebugManager.flags.MinHwThreadsUnoccupied.set(2);
+    uint32_t value = HwHelper::getMaxThreadsForVfe(hwInfo);
+
+    uint32_t expected = hwInfo.gtSystemInfo.EUCount * threadsPerEU - 2;
+    EXPECT_EQ(expected, value);
+}
+
 HWCMDTEST_F(IGFX_GEN8_CORE, PreambleTest, givenPreambleHelperWhenMediaVfeStateIsProgrammedThenOffsetToCommandIsReturned) {
     char buffer[64];
     MockGraphicsAllocation graphicsAllocation(buffer, sizeof(buffer));