Comment by westurner
3 months ago
On MacOS:
sudo dtrace -n 'vfs::*:entry { printf("%-16s %-6d %s", execname, pid, probefunc); }'
sudo dtrace -n 'vfs:lookup:entry { printf("%-16s %-6d %s", execname, pid, copyinstr(arg1)); }'
TIL Dtrace is included in recent builds of Windows 11 and Server 2025: https://learn.microsoft.com/en-us/windows-hardware/drivers/d... ;
# Must be run as Administrator
dtrace -n "syscall::NtCreateFile:entry, syscall::NtReadFile:entry, syscall::NtWriteFile:entry { printf(\"%s (%d) - %s\", execname, pid, probefunc); }"
It's possible to trace file system calls in Windows with procmon.exe by saving a .pmc config file and then loading it from the CLI:
procmon.exe
# uncheck everything except "Show File System Activity"
# Filter > Drop Filtered Events
# File > Export Configuration...
# Must be run as Administrator
procmon.exe /AcceptEula /Quiet /Minimized /LoadConfig C:\Tools\fs-only.pmc /BackingFile C:\Logs\FileSystemTrace.pml
It's also possible to trace lower level file system calls in Windows with logman.exe but it's necessary to parse the traces that it generates.
Then with just bpftrace on Linux:
sudo bpftrace -e 'tracepoint:syscalls:sys_enter_openat { printf("%-6d %-16s %s\n", pid, comm, str(args.filename)); }'
sudo bpftrace -e 'kprobe:vfs_read, kprobe:vfs_write, kprobe:vfs_open { printf("%-16s %-6d %s\n", comm, pid, probefunc); }'
... According to 2.5pro on the cli strs
strace, dtrace, and bpftrace could have a --diff-fs-syscall-files option.
great insights, i'll read up on it and see if it can be useful, thx
np. there's a diagram, "Linux bcc/BPF tracing tools" [-1] in the bcc readme [0] that's also in [1] which explains ebpf and bcc and bpftrace.
filetop, dirtop, and vfsstat use bpf to trace the VFS layer. [4]
[-1] "Linux bcc/BPF tracing tools" https://www.brendangregg.com/BPF/bcc_tracing_tools_early2019...
[0] iovisor/bcc: https://github.com/iovisor/bcc
[1] "Linux Extended BPF (eBPF) Tracing Tools", Dtrace book: https://www.brendangregg.com/ebpf.html
If running an AI agent in a container --- with devcontainers and e.g. vscode,
Good container policy prevents granting a container the CAP_SYS_ADMIN capability; the least-privileges thing to do is to grant limited capabilities to the container like CAP_BPF and (CAP_PERFMON, CAP_NET_RAW, CAP_SYS_PTRACE) [,3].
[3] https://medium.com/@techdevguides/using-bpftrace-with-limite...
[4] bpfcc-tools manpages: https://manpages.debian.org/unstable/bpfcc-tools/index.html
though ripgrep wins, vscode fails at monitoring large workspaces due to inotify limits too; so some way to parse fs events from bcc and libdtrace with python would be great
prompt 1: Create a python project named idk dbpftrace with a pyproject.toml and a README and sphinx /docs, with bcc and python-dtrace as dependencies to, then in dbpftrace/,
parse pid and descendents' fs syscall events from bcc (ebpf) or python-dtrace (dtrace), depending on which os we're running
Edit:
Prompt 1B: Create a Go package named dbpftrace with a README and docs,
parse pid and descendents' fs syscall events from bpftrace or dtrace stdout, depending on which os we're running
Prompt 1C: Create a Go package named dbpftrace with a README and docs, then create a cli utility named dbpftrace to:
parse pid and descendents' fs syscall events (like bpftrace) using libbpfgo and godtrace
Use either (cilium/ebpf or libbpfgo or gobpf) or (godtrace or (CGO or FFI) bindings to libdtrace) depending on which OS, by default
cilium/ebpf: https://github.com/cilium/ebpf
aquasecurity/libbpfgo https://github.com/aquasecurity/libbpfgo
iovisor/gobpf w/ bcc: https://github.com/iovisor/gobpf
chzyer/godtrace: https://github.com/chzyer/godtrace
oracle/dtrace-utils/tree/devel/libdtrace: https://github.com/oracle/dtrace-utils/tree/devel/libdtrace
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