[PATCH v4 0/3] domstats:add haltpolling time statistic interface

[Yang Fei]

This series add the ability to statistic the halt polling time when
VM execute HLT(arm is WFI).

v1:
https://listman.redhat.com/archives/libvir-list/2021-July/msg00029.html
v2:
https://listman.redhat.com/archives/libvir-list/2021-July/msg00339.html
v3:
https://listman.redhat.com/archives/libvir-list/2021-July/msg00445.html

changes from v1:
- Move virGetCgroupValueRaw to utils.c and rename it virGetValueRaw. So
  that we can call it to obtain halt polling time.
- Helper function virGetCpuHaltPollTime and virGetDebugFsKvmValue are
  added in a separate patch
- Use STRPREFIX to match the path prefix.
- Fix the logic that domstats will break when platform is non-linux,
  debugfs isn't mounted and so on.

change from v2:
- Drop patch 1, use virFileReadValueUllong() to get halt polling data.
- Delete unnecessary error report in logs.
- Remove the qemuDomainGetStatsCpuHaltPollTime function conditionally
  compiled on linux.
- Document the new parameters in src/libvirt-domain.c.

change from v3:
- Add function virFileReadValueUllongQuiet without error report.
- Move virGetCpuHaltPollTime to src/util/virhostcpu.c and change the
  name to virHostCPUGetHaltPollTime.
- Replace the function which will report errors:
  virDirOpenIfExists -> virDirOpenQuiet
  virFileReadValueUllong -> virFileReadValueUllongQuiet

Yang Fei (3):
  util: Add virFileReadValueUllongQuiet
  util: Add virHostCPUGetHaltPollTime
  qemu: Introduce qemuDomainGetStatsCpuHaltPollTime

 docs/manpages/virsh.rst  |  4 ++++
 src/libvirt-domain.c     |  7 +++++++
 src/libvirt_private.syms |  2 ++
 src/qemu/qemu_driver.c   | 20 ++++++++++++++++++++
 src/util/virfile.c       | 24 ++++++++++++++++++++++++
 src/util/virfile.h       |  2 ++
 src/util/virhostcpu.c    | 39 +++++++++++++++++++++++++++++++++++++++
 src/util/virhostcpu.h    |  4 ++++
 8 files changed, 102 insertions(+)

-- 
2.23.0