sysinfo.cr

Cross-platform system & process memory info for Crystal — a small port of the Rust sysinfo crate's surface:

• Sysinfo.memory — global RAM: total_kb / available_kb / used_kb / percent
• Sysinfo.refresh_processes — rebuild the pid / parent / RSS snapshot
• Sysinfo.processes — the last snapshot (Sysinfo::Process entries)
• Sysinfo.process_tree_memory_kb(pid) — RSS of a process and all its descendants (what a terminal tab actually uses: the shell plus its compilers/servers/agents), cycle-safe
• Sysinfo.refresh_cpu / Sysinfo.cpu_percentages — per-core busy percent since the previous sample (first call is a baseline of zeros)
• Sysinfo.refresh_network / Sysinfo.network — bytes received/sent since boot plus average rates since the previous sample, loopback excluded
• Sysinfo.refresh_gpus / Sysinfo.gpus — one Sysinfo::Gpu per card: load, VRAM used/total/percent, temperature, power and power limit (plus PCIe gen/width on NVIDIA). Unreadable values are nil; nothing here can raise into the caller.
• Sysinfo.refresh_sensors / Sysinfo.sensors — one Sysinfo::Sensor per temperature input (chip, label, current / max / critical °C). Unreadable values are nil; nothing here can raise into the caller.

The library is synchronous, like the Rust crate — callers decide when and where to refresh (h2term hides it on a background fiber).

Backends

Platform	RAM	Process table	CPU cores	Network	GPU	Temp sensors
Linux	/proc/meminfo	/proc/<pid>/status (PPid + VmRSS)	/proc/stat	/proc/net/dev	NVML (dlopen) + amdgpu sysfs + Level Zero (dlopen)	hwmon sysfs
macOS	sysctl + host_statistics64	libproc (proc_listallpids, proc_pidinfo)	host_processor_info	sysctl(NET_RT_IFLIST2)	—	—
Windows	GlobalMemoryStatusEx	Toolhelp32 + GetProcessMemoryInfo	NtQuerySystemInformation	GetIfTable2	NVML (LoadLibraryA) + Level Zero (LoadLibraryA)	—
Other	nil	empty	—	—	—	—

GPU readings come from the same sources Strata's monitor uses: NVIDIA's own NVML library, loaded at runtime from the driver (libnvidia-ml.so.1 / nvml.dll) so there is no compile-time binding, and — on Linux — the amdgpu driver's sysfs files (KFD topology → renderD* device → gpu_busy_percent, mem_info_vram_*, the hwmon temperature/power sensors); no ROCm library needed. AMD on Windows would need ADL, so it is not covered there.

Intel GPUs (integrated and Arc) go through Level Zero Sysman, Intel's cross-platform GPU API (Linux libze_loader.so.1 from the intel-level-zero-gpu package, Windows ze_loader.dll from the graphics driver), runtime-loaded the same way as NVML. VRAM and temperature are point-in-time reads — on iGPUs the memory module is the shared-memory budget the driver exposes, not dedicated chips — while engine load and power are monotonic counters, so they are computed between two refresh_gpus calls (the first refresh reports nil).

On Linux /proc's top level lists only thread-group leaders, so per-thread RSS can never be double-counted (upstream sysinfo has to filter thread entries explicitly). On macOS, proc_pidinfo only succeeds for processes the current uid may signal; the snapshot skips everyone else.

Temperature sensors come from hwmon sysfs (/sys/class/hwmon) on Linux — the same tree the sensors tool reads: one Sysinfo::Sensor per temp<N>_input (CPU packages and cores, drive controllers, GPUs, ACPI zones), with the chip name, the sensor label and the driver's max/critical limits when it publishes them. Windows (WMI/SMBIOS) and macOS (SMC) would each need their own plumbing and report no sensors here.

Use

require "sysinfo"

if mem = Sysinfo.memory
  puts "RAM #{mem.used_kb // 1024}/#{mem.total_kb // 1024} MB (#{mem.percent}%)"
end

Sysinfo.refresh_processes
Sysinfo.process_tree_memory_kb(Process.pid) # => whole tree RSS in KB

A live monitor example (per-core CPU load, RAM, network throughput, GPU readings, temperature sensors) lives in example/monitor.cr:

crystal run example/monitor.cr

macOS note: on current kernels the interface byte counters come back with the high 32 bits zeroed, so totals wrap at 4 GB — the rate math uses wrapping deltas and stays correct across the wrap.

Test

crystal spec