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Diffstat (limited to 'src/vm/perfdefaults.cpp')
| -rw-r--r-- | src/vm/perfdefaults.cpp | 147 |
1 files changed, 147 insertions, 0 deletions
diff --git a/src/vm/perfdefaults.cpp b/src/vm/perfdefaults.cpp new file mode 100644 index 0000000000..f6352bcd53 --- /dev/null +++ b/src/vm/perfdefaults.cpp @@ -0,0 +1,147 @@ +// Licensed to the .NET Foundation under one or more agreements. +// The .NET Foundation licenses this file to you under the MIT license. +// See the LICENSE file in the project root for more information. +//************************************************************************************************* +// PerfDefaults.cpp +// + +// +// Implementation of the "PerformanceScenario" config option, which defines a workload-specific +// set of performance defaults. The key point of the code below is that it be clear exactly what +// gets enabled for each scenario -- see the switch statements +// +// for host STARTUP_FLAGS, in GetModifiedStartupFlags +// for environment, registry, or config CLRConfig values, in LookupConfigValue +// for other global initialization, in InitializeForScenario +// +//************************************************************************************************* + +#include "common.h" +#include "perfdefaults.h" + +// Useful to the readability of lists of settings below +#define MATCHES(a,b) (SString::_wcsicmp((a),(b)) == 0) + +// The scenario we have been asked to run under +PerformanceDefaults::PerformanceScenario PerformanceDefaults::s_Scenario = Uninitialized; + +// See use in code:PerformanceDefaults:InitializeForScenario +extern int32_t g_bLowMemoryFromHost; + + +// +// Initialize our system to provide performance defaults for a given scenario. +// If the scenario name is not recognized, intentionally ignore it and operate as if not specified. +// + void PerformanceDefaults::InitializeForScenario(__in_opt LPWSTR scenarioName) +{ + LIMITED_METHOD_CONTRACT; + + // First convert the scenario name to the corresponding enum value + s_Scenario = None; + if (scenarioName != NULL) + { + if (MATCHES(scenarioName, W("HighDensityWebHosting"))) s_Scenario = HighDensityWebHosting; + } + + // Next do any scenario-specific initialization + switch (s_Scenario) + { + case None: + break; + + case HighDensityWebHosting: + // Tell the hosting API that we want the GC to operate as if the machine is under memory pressure. + // This is a workaround because we do not want to expose "force low memory mode" as either a CLR + // config option or a host startup flag (the two types of knob that PerformanceDefaults can alter) and + // ASP.Net has not yet become a memory host. When they do, this can be removed and they can + // make an initial call to ICLRMemoryNotificationCallback:OnMemoryNotification(eMemoryAvailableLow). + // + // Note that in order for ASP.Net to become a memory host the CLR will need to support profiler attach + // in that condition. + g_bLowMemoryFromHost = 1; + break; + + case Uninitialized: + // Unreachable, but make GCC happy + break; + } + + // Finally register our lookup function with the CLRConfig system so we get called when a 'MayHavePerformanceDefault' + // config option is about to resolve to its runtime default + if (s_Scenario != None) + { + CLRConfig::RegisterGetPerformanceDefaultValueCallback(&LookupConfigValue); + } +} + + +// +// Called at runtime startup to allow host-specified STARTUP_FLAGS to be overridden when running +// under a scenario. +// +// Note that we are comfortable overriding the values the host has asked us to use (see +// file:PerfDefaults.h), but we never want to override a value specified by a user to CLRConfig. +// This comes up here because there are settings that are configurable through both systems. +// So where an option has both STARTUP_FLAG A and CLRConfig value B, first check whether B has +// been specified before altering the value of A. This way, we maintain complete compatibility +// with whatever the interaction of A and B has produced in the past. +// +STARTUP_FLAGS PerformanceDefaults::GetModifiedStartupFlags(STARTUP_FLAGS originalFlags) +{ + LIMITED_METHOD_CONTRACT; + + DWORD newFlags = (DWORD)originalFlags; + + switch (s_Scenario) + { + case None: + break; + + case HighDensityWebHosting: + if (!CLRConfig::IsConfigOptionSpecified(W("gcServer"))) newFlags &= ~STARTUP_SERVER_GC; + if (!CLRConfig::IsConfigOptionSpecified(W("gcConcurrent"))) newFlags &= ~STARTUP_CONCURRENT_GC; + if (!CLRConfig::IsConfigOptionSpecified(W("gcTrimCommitOnLowMemory"))) newFlags |= STARTUP_TRIM_GC_COMMIT; + + break; + + case Uninitialized: + // Check that no request for startup flags happens before our code has been initialized + // and given a chance to modify them. + _ASSERTE(!"PerformanceDefaults::InitializeForScenario should have already been called"); + break; + } + + return (STARTUP_FLAGS)newFlags; +} + + +// +// Called by the CLRConfig system whenever a 'MayHavePerformanceDefault' config option is about +// to resolve to its runtime default (i.e. none of the corresponding environment variable, registry, or +// config file values were specified). +// +BOOL PerformanceDefaults::LookupConfigValue(LPCWSTR name, DWORD *pValue) +{ + LIMITED_METHOD_CONTRACT; + _ASSERTE(pValue != NULL); + + switch (s_Scenario) + { + case None: + return FALSE; + + case HighDensityWebHosting: + if (MATCHES(name, W("shadowCopyVerifyByTimestamp"))) { *pValue = 1; return TRUE; } + return FALSE; + + case Uninitialized: + // Check that no request for a MayHavePerformanceDefault CLRConfig option happens + // before our code has been initialized and given a chance to provide a default value. + _ASSERTE(!"PerformanceDefaults::InitializeForScenario should have already been called"); + break; + } + + return FALSE; +} + |