Linux /proc/ stats (#45)

resource usage statistics on linux

- Parse /proc/<pid>/stat{,m}
- Divide {s,u}time by _SC_CLK_TCK
- Compute runtime from {s,u}time

Co-authored-by: Hannes Mehnert <hannes@mehnert.org>
This commit is contained in:
Reynir Björnsson 2020-11-26 12:02:21 +01:00 committed by GitHub
parent 7dc2e33ef0
commit 3de997a7c1
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2 changed files with 108 additions and 1 deletions

View file

@ -5,6 +5,8 @@ open Rresult.R.Infix
open Vmm_core
external sysconf_clock_tick : unit -> int = "vmmanage_sysconf_clock_tick"
external sysctl_kinfo_proc : int -> Stats.rusage * Stats.kinfo_mem =
"vmmanage_sysctl_kinfo_proc"
external sysctl_ifcount : unit -> int = "vmmanage_sysctl_ifcount"
@ -99,9 +101,103 @@ let try_open_vmmapi pid_nic =
IM.add pid (vmctx, vmmdev, nics) fresh)
pid_nic IM.empty
let string_of_file filename =
try
let fh = open_in filename in
let content = input_line fh in
close_in_noerr fh ;
Ok content
with _ -> Rresult.R.error_msgf "Error reading file %S" filename
let parse_proc_stat s =
let stats_opt =
let ( let* ) = Option.bind in
let* (pid, rest) = Astring.String.cut ~sep:" (" s in
let* (tcomm, rest) = Astring.String.cut ~rev:true ~sep:") " rest in
let rest = Astring.String.cuts ~sep:" " rest in
Some (pid :: tcomm :: rest)
in
Option.to_result ~none:(`Msg "unable to parse /proc/<pid>/stat") stats_opt
let read_proc_status pid =
try
let fh = open_in ("/proc/" ^ string_of_int pid ^ "/status") in
let lines =
let rec read_lines acc = try
read_lines (input_line fh :: acc)
with End_of_file -> acc in
read_lines []
in
List.map (Astring.String.cut ~sep:":\t") lines |>
List.fold_left (fun acc x -> match acc, x with
| Some acc, Some x -> Some (x :: acc)
| _ -> None) (Some []) |>
Option.to_result ~none:(`Msg "failed to parse /proc/<pid>/status")
with _ -> Rresult.R.error_msgf "error reading file /proc/%d/status" pid
let linux_rusage pid =
(match Unix.stat ("/proc/" ^ string_of_int pid) with
| { Unix.st_ctime = start; _ } ->
let frac = Float.rem start 1. in
Ok (Int64.of_float start, int_of_float (frac *. 1_000_000.))
| exception Unix.Unix_error (Unix.ENOENT,_,_) -> Error (`Msg "failed to stat process") ) >>= fun start ->
(* reading /proc/<pid>/stat - since it may disappear mid-time,
best to have it in memory *)
string_of_file ("/proc/" ^ string_of_int pid ^ "/stat") >>= fun data ->
parse_proc_stat data >>= fun stat_vals ->
string_of_file ("/proc/" ^ string_of_int pid ^ "/statm") >>= fun data ->
let statm_vals = Astring.String.cuts ~sep:" " data in
read_proc_status pid >>= fun status ->
let assoc_i64 key : (int64, _) result =
let e x = Option.to_result ~none:(`Msg "error parsing /proc/<pid>/status") x in
e (List.assoc_opt key status) >>= fun v ->
e (Int64.of_string_opt v)
in
let i64 s = try Ok (Int64.of_string s) with
Failure _ -> Error (`Msg "couldn't parse integer")
in
let time_of_int64 t =
let clock_tick = Int64.of_int (sysconf_clock_tick ()) in
let ( * ) = Int64.mul and ( / ) = Int64.div in
(t / clock_tick, Int64.to_int (((Int64.rem t clock_tick) * 1_000_000L) / clock_tick))
in
if List.length stat_vals >= 52 && List.length statm_vals >= 7 then
i64 (List.nth stat_vals 9) >>= fun minflt ->
i64 (List.nth stat_vals 11) >>= fun majflt ->
i64 (List.nth stat_vals 13) >>= fun utime -> (* divide by sysconf(_SC_CLK_TCK) *)
i64 (List.nth stat_vals 14) >>= fun stime -> (* divide by sysconf(_SC_CLK_TCK) *)
let runtime = fst (time_of_int64 Int64.(add utime stime)) in
let utime = time_of_int64 utime
and stime = time_of_int64 stime in
i64 (List.nth stat_vals 22) >>= fun vsize -> (* in bytes *)
i64 (List.nth stat_vals 23) >>= fun rss -> (* in pages *)
i64 (List.nth stat_vals 35) >>= fun nswap -> (* not maintained, 0 *)
i64 (List.nth statm_vals 3) >>= fun tsize ->
i64 (List.nth statm_vals 5) >>= fun dsize -> (* data + stack *)
i64 (List.nth statm_vals 5) >>= fun ssize -> (* data + stack *)
assoc_i64 "voluntary_ctxt_switches" >>= fun nvcsw ->
assoc_i64 "nonvoluntary_ctxt_switches" >>= fun nivcsw ->
let rusage = { Stats.utime ; stime ; maxrss = rss ; ixrss = 0L ;
idrss = 0L ; isrss = 0L ; minflt ; majflt ; nswap ; inblock = 0L ; outblock = 0L ;
msgsnd = 0L ; msgrcv = 0L ; nsignals = 0L ; nvcsw ; nivcsw }
and kmem = { Stats.vsize; rss; tsize; dsize; ssize; runtime; cow = 0; start }
in
Ok (rusage, kmem)
else
Error (`Msg "couldn't read /proc/<pid>/stat")
let rusage pid =
match Lazy.force Vmm_unix.uname with
| Vmm_unix.FreeBSD -> wrap sysctl_kinfo_proc pid
| Vmm_unix.Linux -> match linux_rusage pid with
| Ok x -> Some x
| Error (`Msg msg) ->
Logs.err (fun m -> m "error %s while reading /proc/" msg);
None
let gather pid vmctx nics =
let ru, mem =
match wrap sysctl_kinfo_proc pid with
match rusage pid with
| None -> None, None
| Some (mem, ru) -> Some mem, Some ru
in

View file

@ -17,6 +17,17 @@
#define Val32 caml_copy_int32
#define Val64 caml_copy_int64
/* We only use sysconf(_SC_CLK_TCK) in Linux only, but it's well-defined in FreeBSD as well. */
#include <unistd.h>
CAMLprim value vmmanage_sysconf_clock_tick(value unit) {
CAMLparam1(unit);
long r;
r = sysconf(_SC_CLK_TCK);
if (r == 1)
uerror("sysconf", Nothing);
CAMLreturn(Val_long(r));
}
#ifdef __FreeBSD__
#include <net/if_mib.h>
#include <vmmapi.h>