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Fix additional issue to support >1024 CPUs #127572

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Merged
janvorli merged 2 commits into from
May 13, 2026
Merged

Fix additional issue to support >1024 CPUs #127572

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9df622d
Fix additional issue to support >1024 CPUs
janvorli Apr 29, 2026
5789e1e
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janvorli Apr 30, 2026
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23 changes: 18 additions & 5 deletions src/coreclr/gc/unix/gcenv.unix.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -116,6 +116,9 @@ typedef cpuset_t cpu_set_t;
// The cached total number of CPUs that can be used in the OS.
uint32_t g_totalCpuCount = 0;

// The number of CPUs that are configured in the OS.
uint32_t g_configuredCpuCount = 0;

size_t GetRestrictedPhysicalMemoryLimit();
bool GetPhysicalMemoryUsed(size_t* val);

Expand Down Expand Up @@ -158,6 +161,7 @@ bool GCToOSInterface::Initialize()
}

g_totalCpuCount = cpuCount;
g_configuredCpuCount = configuredCpuCount;

if (!g_processAffinitySet.Initialize(configuredCpuCount))
{
Expand Down Expand Up @@ -904,9 +908,16 @@ size_t GCToOSInterface::GetCacheSizePerLogicalCpu(bool trueSize)
bool GCToOSInterface::SetThreadAffinity(uint16_t procNo)
{
#if HAVE_SCHED_SETAFFINITY || HAVE_PTHREAD_SETAFFINITY_NP
cpu_set_t cpuSet;
CPU_ZERO(&cpuSet);
CPU_SET((int)procNo, &cpuSet);

size_t cpuSetSize = CPU_ALLOC_SIZE(g_configuredCpuCount);
cpu_set_t* pCpuSet = CPU_ALLOC(g_configuredCpuCount);
if (pCpuSet == nullptr)
{
return false;
}

CPU_ZERO_S(cpuSetSize, pCpuSet);
CPU_SET_S((int)procNo, cpuSetSize, pCpuSet);
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// Snap's default strict confinement does not allow sched_setaffinity(<nonzeroPid>, ...) without manually connecting the
// process-control plug. sched_setaffinity(<currentThreadPid>, ...) is also currently not allowed, only
Expand All @@ -918,11 +929,13 @@ bool GCToOSInterface::SetThreadAffinity(uint16_t procNo)
// - https://github.com/dotnet/runtime/issues/1634
// - https://forum.snapcraft.io/t/requesting-autoconnect-for-interfaces-in-pigmeat-process-control-home/17987/13
#if HAVE_SCHED_SETAFFINITY
int st = sched_setaffinity(0, sizeof(cpu_set_t), &cpuSet);
int st = sched_setaffinity(0, cpuSetSize, pCpuSet);
#else
int st = pthread_setaffinity_np(pthread_self(), sizeof(cpu_set_t), &cpuSet);
int st = pthread_setaffinity_np(pthread_self(), cpuSetSize, pCpuSet);
#endif

CPU_FREE(pCpuSet);

return (st == 0);

#else // !(HAVE_SCHED_SETAFFINITY || HAVE_PTHREAD_SETAFFINITY_NP)
Expand Down
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