[PATCH v2 2/2] Use virProcessGetStat

[Martin Kletzander]

On Mon, Nov 22, 2021 at 09:59:07AM +0000, Daniel P. Berrangé wrote:
>On Mon, Nov 22, 2021 at 10:34:38AM +0100, Martin Kletzander wrote:
>> On Mon, Nov 22, 2021 at 09:18:41AM +0000, Daniel P. Berrangé wrote:
>> > On Sun, Nov 21, 2021 at 12:04:26AM +0100, Martin Kletzander wrote:
>> > > This eliminates one incorrect parsing implementation.
>> >
>> > Please explain what was being done wrongly / what was the
>> > effect of the bug ?
>> >
>>
>> One of the implementations was just looking for first closing
>> parenthesis to find the end of the command name, which should be done by
>> looking at the _last_ closing parenthesis.  This might fail in a very
>> small corner case which is tested for in the first patch.  But you are
>> right, I should add this to the commit message.  Will do in v3.
>>
>> > >
>> > > Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
>> > > ---
>> > >  src/qemu/qemu_driver.c | 33 ++++++-----------------------
>> > >  src/util/virprocess.c  | 48 ++++++------------------------------------
>> > >  2 files changed, 12 insertions(+), 69 deletions(-)
>> > >
>> > > diff --git a/src/qemu/qemu_driver.c b/src/qemu/qemu_driver.c
>> > > index d954635dde2a..0468d6aaf314 100644
>> > > --- a/src/qemu/qemu_driver.c
>> > > +++ b/src/qemu/qemu_driver.c
>> > > @@ -1399,36 +1399,17 @@ qemuGetSchedInfo(unsigned long long *cpuWait,
>> > >
>> > >  static int
>> > >  qemuGetProcessInfo(unsigned long long *cpuTime, int *lastCpu, long *vm_rss,
>> > > -                   pid_t pid, int tid)
>> > > +                   pid_t pid, pid_t tid)
>> > >  {
>> > > -    g_autofree char *proc = NULL;
>> > > -    FILE *pidinfo;
>> > > +    g_auto(GStrv) proc_stat = virProcessGetStat(pid, tid);
>> > >      unsigned long long usertime = 0, systime = 0;
>> > >      long rss = 0;
>> > >      int cpu = 0;
>> > >
>> > > -    /* In general, we cannot assume pid_t fits in int; but /proc parsing
>> > > -     * is specific to Linux where int works fine.  */
>> > > -    if (tid)
>> > > -        proc = g_strdup_printf("/proc/%d/task/%d/stat", (int)pid, tid);
>> > > -    else
>> > > -        proc = g_strdup_printf("/proc/%d/stat", (int)pid);
>> > > -    if (!proc)
>> > > -        return -1;
>> > > -
>> > > -    pidinfo = fopen(proc, "r");
>> > > -
>> > > -    /* See 'man proc' for information about what all these fields are. We're
>> > > -     * only interested in a very few of them */
>> > > -    if (!pidinfo ||
>> > > -        fscanf(pidinfo,
>> > > -               /* pid -> stime */
>> > > -               "%*d (%*[^)]) %*c %*d %*d %*d %*d %*d %*u %*u %*u %*u %*u %llu %llu"
>> > > -               /* cutime -> endcode */
>> > > -               "%*d %*d %*d %*d %*d %*d %*u %*u %ld %*u %*u %*u"
>> > > -               /* startstack -> processor */
>> > > -               "%*u %*u %*u %*u %*u %*u %*u %*u %*u %*u %*d %d",
>> > > -               &usertime, &systime, &rss, &cpu) != 4) {
>> > > +    if (virStrToLong_ullp(proc_stat[13], NULL, 10, &usertime) < 0 ||
>> > > +        virStrToLong_ullp(proc_stat[14], NULL, 10, &systime) < 0 ||
>> > > +        virStrToLong_l(proc_stat[23], NULL, 10, &rss) < 0 ||
>> > > +        virStrToLong_i(proc_stat[38], NULL, 10, &cpu) < 0) {
>> >
>> > Since you're adding a formal API, I think we'd benefit from
>> > constants for these array indexes in virprocess.h
>> >
>>
>> I was thinking about that and also tried figuring out how to encode the
>> proper field types in the header file.  But since we are not doing lot
>> of /proc/*/stat parsing in our codebase I though that would be an
>> overkill.  I'll add at least the constants.
>
>BTW ,didn't mean we need constants for all 40+ fields - just the ones
>we actually use.
>

oops, too late, at least it is now complete =)

>Regards,
>Daniel
>-- 
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>
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