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Re: [libvirt] [PATCH v3 1/2] process: wait longer on kill per assigned Hostdev



On Tue, Aug 14, 2018 at 11:27:33AM +0200, Christian Ehrhardt wrote:
> It was found that in cases with host devices virProcessKillPainfully
> might be able to send signal zero to the target PID for quite a while
> with the process already being gone from /proc/<PID>.
> 
> That is due to cleanup and reset of devices which might include a
> secondary bus reset that on top of the actions taken has a 1s delay
> to let the bus settle. Due to that guests with plenty of Host devices
> could easily exceed the default timeouts.
> 
> To solve that, this adds an extra delay of 2s per hostdev that is associated
> to a VM.
> 
> Signed-off-by: Christian Ehrhardt <christian ehrhardt canonical com>
> ---
>  src/libvirt_private.syms |  1 +
>  src/qemu/qemu_process.c  |  5 +++--
>  src/util/virprocess.c    | 18 +++++++++++++++---
>  src/util/virprocess.h    |  1 +
>  4 files changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/src/libvirt_private.syms b/src/libvirt_private.syms
> index ca4a192a4a..47ea35f864 100644
> --- a/src/libvirt_private.syms
> +++ b/src/libvirt_private.syms
> @@ -2605,6 +2605,7 @@ virProcessGetPids;
>  virProcessGetStartTime;
>  virProcessKill;
>  virProcessKillPainfully;
> +virProcessKillPainfullyDelay;
>  virProcessNamespaceAvailable;
>  virProcessRunInMountNamespace;
>  virProcessSchedPolicyTypeFromString;
> diff --git a/src/qemu/qemu_process.c b/src/qemu/qemu_process.c
> index 02fdc55156..b7bf8813da 100644
> --- a/src/qemu/qemu_process.c
> +++ b/src/qemu/qemu_process.c
> @@ -6814,8 +6814,9 @@ qemuProcessKill(virDomainObjPtr vm, unsigned int flags)
>          return 0;
>      }
>  
> -    ret = virProcessKillPainfully(vm->pid,
> -                                  !!(flags & VIR_QEMU_PROCESS_KILL_FORCE));
> +    ret = virProcessKillPainfullyDelay(vm->pid,
> +                                       !!(flags & VIR_QEMU_PROCESS_KILL_FORCE),
> +                                       vm->def->nhostdevs * 2);

This API contract is a bit wierd. You've got an arbitray x2 multiplier
here...

> diff --git a/src/util/virprocess.c b/src/util/virprocess.c
> index ecea27a2d4..46360cc051 100644
> --- a/src/util/virprocess.c
> +++ b/src/util/virprocess.c
> @@ -341,15 +341,19 @@ int virProcessKill(pid_t pid, int sig)
>   * Returns 0 if it was killed gracefully, 1 if it
>   * was killed forcibly, -1 if it is still alive,
>   * or another error occurred.
> + *
> + * Callers can proide an extra delay to wait longer
> + * than the default.

Mention that it is in "seconds"

>   */
>  int
> -virProcessKillPainfully(pid_t pid, bool force)
> +virProcessKillPainfullyDelay(pid_t pid, bool force, unsigned int extradelay)
>  {
>      size_t i;
>      int ret = -1;
> +    unsigned int delay = 75 + (extradelay*5);

...and it gets another x5 multiplier here.

Feels nicer to just have the caller provide a x10 multiplier and
honour that directly

>      const char *signame = "TERM";
>  
> -    VIR_DEBUG("vpid=%lld force=%d", (long long)pid, force);
> +    VIR_DEBUG("vpid=%lld force=%d delay=%u", (long long)pid, force, pid);

s/pid/extradelay/

>  
>      /* This loop sends SIGTERM, then waits a few iterations (10 seconds)
>       * to see if it dies. If the process still hasn't exited, and
> @@ -357,9 +361,12 @@ virProcessKillPainfully(pid_t pid, bool force)
>       * wait up to 5 seconds more for the process to exit before
>       * returning.
>       *
> +     * An extra delay can be specified for cases that are expected to clean
> +     * up slower than usual.
> +     *
>       * Note that setting @force could result in dataloss for the process.
>       */
> -    for (i = 0; i < 75; i++) {
> +    for (i = 0; i < delay; i++) {
>          int signum;
>          if (i == 0) {
>              signum = SIGTERM; /* kindly suggest it should exit */
> @@ -402,6 +409,11 @@ virProcessKillPainfully(pid_t pid, bool force)
>  }
>  
>  
> +int virProcessKillPainfully(pid_t pid, bool force)
> +{
> +    return virProcessKillPainfullyDelay(pid, force, 0);
> +}
> +
>  #if HAVE_SCHED_GETAFFINITY
>  
>  int virProcessSetAffinity(pid_t pid, virBitmapPtr map)
> diff --git a/src/util/virprocess.h b/src/util/virprocess.h
> index 3c5a882772..b72603ca8e 100644
> --- a/src/util/virprocess.h
> +++ b/src/util/virprocess.h
> @@ -55,6 +55,7 @@ virProcessWait(pid_t pid, int *exitstatus, bool raw)
>  int virProcessKill(pid_t pid, int sig);
>  
>  int virProcessKillPainfully(pid_t pid, bool force);
> +int virProcessKillPainfullyDelay(pid_t pid, bool force, unsigned int);

Missing parameter name here

Regards,
Daniel
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