Implementation:Ollama Ollama Discover CPU Windows

Knowledge Sources	Ollama
Domains	HardwareDiscovery, Windows
Last Updated	2025-02-15 00:00 GMT

Overview

Windows-specific CPU memory and topology discovery module that calls Win32 APIs via syscall to determine available system resources including efficiency core detection.

Description

GetCPUMem calls GlobalMemoryStatusEx from kernel32.dll using unsafe pointer casting to populate a MEMORYSTATUSEX struct with total physical memory, available memory, and available page file. GetCPUDetails calls GetLogicalProcessorInformationEx to retrieve a raw byte buffer of processor relationship data, then processSystemLogicalProcessorInforationList parses it in three passes: first identifying CPU packages (sockets) with their group affinities, then determining the maximum efficiency class across all cores (to detect Intel hybrid P-core/E-core architectures), and finally matching cores to packages while counting total cores, threads, and efficiency cores based on EfficiencyClass and Flags fields. IsNUMA always returns false since NUMA support in ggml is Linux-only.

Usage

Called during Ollama startup on Windows to determine available system resources for optimal model loading and inference thread allocation.

Code Reference

Source Location

• Repository: Ollama
• File: discover/cpu_windows.go
• Lines: 1-221

Signature

func GetCPUMem() (memInfo, error)
func GetCPUDetails() []CPU
func IsNUMA() bool

type MEMORYSTATUSEX struct {
    length               uint32
    MemoryLoad           uint32
    TotalPhys            uint64
    AvailPhys            uint64
    TotalPageFile        uint64
    AvailPageFile        uint64
    TotalVirtual         uint64
    AvailVirtual         uint64
    AvailExtendedVirtual uint64
}

type winPackage struct {
    groups              []*GROUP_AFFINITY
    coreCount           int
    efficiencyCoreCount int
    threadCount         int
}

Import

import "github.com/ollama/ollama/discover"

I/O Contract

Inputs

Name	Type	Required	Description
kernel32.dll	Win32 DLL	Yes	Windows kernel library for memory and processor APIs
GlobalMemoryStatusEx	Win32 API	Yes	System memory status
GetLogicalProcessorInformationEx	Win32 API	Yes	Processor topology information

Outputs

Name	Type	Description
memInfo	struct	TotalMemory, FreeMemory, FreeSwap in bytes
[]CPU	slice	List of CPU packages with core/thread/efficiency counts
isNUMA	bool	Always false on Windows

Usage Examples

mem, err := discover.GetCPUMem()
if err != nil {
    log.Fatal(err)
}
fmt.Printf("Total: %d bytes, Available: %d bytes\n",
    mem.TotalMemory, mem.FreeMemory)

cpus := discover.GetCPUDetails()
for _, cpu := range cpus {
    fmt.Printf("Package: %d cores (%d efficiency), %d threads\n",
        cpu.CoreCount, cpu.EfficiencyCoreCount, cpu.ThreadCount)
}

Related Pages

• Principle:Ollama_Ollama_HardwareDiscovery