[PATCH 1/2] util: Extend virProcessGetStatInfo() for sysTime and userTime

[Ján Tomko]

On a Monday in 2022, Michal Privoznik wrote:
>The virProcessGetStatInfo() helper parses /proc stat file for
>given PID and/or TID and reports cumulative cpuTime which is just
>a sum of user and sys times. But in near future, we'll need those
>times separately, so make the function return them too (if caller
>desires).
>
>Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>---
> src/ch/ch_driver.c     |  1 +
> src/qemu/qemu_driver.c |  4 +++-
> src/util/virprocess.c  | 30 +++++++++++++++++++++++-------
> src/util/virprocess.h  |  2 ++
> 4 files changed, 29 insertions(+), 8 deletions(-)
>
>diff --git a/src/util/virprocess.c b/src/util/virprocess.c
>index 013afd91b4..4cc75b8b45 100644
>--- a/src/util/virprocess.c
>+++ b/src/util/virprocess.c
>@@ -1737,19 +1737,24 @@ virProcessGetStat(pid_t pid,
> #ifdef __linux__
> int
> virProcessGetStatInfo(unsigned long long *cpuTime,
>+                      unsigned long long *sysTime,
>+                      unsigned long long *userTime,

I would expect these to be swapped. time(1) reports user time
before sys time, and they are in that order also in /proc/$PID/stat

>                       int *lastCpu,
>                       long *vm_rss,
>                       pid_t pid,
>                       pid_t tid)
> {
>     g_auto(GStrv) proc_stat = virProcessGetStat(pid, tid);
>-    unsigned long long usertime = 0, systime = 0;
>+    unsigned long long utime = 0;
>+    unsigned long long stime = 0;
>+    const unsigned long long jiff2sec = 1000ull * 1000ull * 1000ull /
>+                                        (unsigned long long) sysconf(_SC_CLK_TCK);
>     long rss = 0;
>     int cpu = 0;
>
>     if (!proc_stat ||
>-        virStrToLong_ullp(proc_stat[VIR_PROCESS_STAT_UTIME], NULL, 10, &usertime) < 0 ||
>-        virStrToLong_ullp(proc_stat[VIR_PROCESS_STAT_STIME], NULL, 10, &systime) < 0 ||
>+        virStrToLong_ullp(proc_stat[VIR_PROCESS_STAT_UTIME], NULL, 10, &utime) < 0 ||
>+        virStrToLong_ullp(proc_stat[VIR_PROCESS_STAT_STIME], NULL, 10, &stime) < 0 ||
>         virStrToLong_l(proc_stat[VIR_PROCESS_STAT_RSS], NULL, 10, &rss) < 0 ||
>         virStrToLong_i(proc_stat[VIR_PROCESS_STAT_PROCESSOR], NULL, 10, &cpu) < 0) {
>         VIR_WARN("cannot parse process status data");
>@@ -1758,11 +1763,16 @@ virProcessGetStatInfo(unsigned long long *cpuTime,
>     /* We got jiffies
>      * We want nanoseconds
>      * _SC_CLK_TCK is jiffies per second
>-     * So calculate thus....
>+     * So calculate this....
>      */
>+    utime *= jiff2sec;
>+    stime *= jiff2sec;

By using the descriptive constnant name, we no longer need the
multi-line comment.

But it converts to ns, so 'jiff2ns' or 'jiff2nsec' would be more
appropriate.

Jano

>     if (cpuTime)
>-        *cpuTime = 1000ull * 1000ull * 1000ull * (usertime + systime)
>-            / (unsigned long long) sysconf(_SC_CLK_TCK);
>+        *cpuTime = utime + stime;
>+    if (sysTime)
>+        *sysTime = stime;
>+    if (userTime)
>+        *userTime = utime;
>     if (lastCpu)
>         *lastCpu = cpu;