1. Patchew
  2. Libvirt
  3. View series

[PATCH v2] util: virHostCPUGetStatsLinux: add guest_nice to VIR_NODE_CPU_STATS_GUEST

Claudio Fontana posted 1 patch 1 week ago
Patches applied successfully (tree, apply log)
git fetch https://github.com/patchew-project/libvirt tags/patchew/20260617161437.3638-1-cfontana@suse.de
src/util/virhostcpu.c                         | 2 +-
tests/virhostcpudata/linux-cpustat-24cpu.out  | 8 ++++----
tests/virhostcpudata/linux-cpustat-24cpu.stat | 4 ++--
3 files changed, 7 insertions(+), 7 deletions(-)
[PATCH v2] util: virHostCPUGetStatsLinux: add guest_nice to VIR_NODE_CPU_STATS_GUEST
Posted by Claudio Fontana 1 week ago 
On Linux the accounting stats come from /proc/stat entries and the mapping is:

https://www.kernel.org/doc/html/latest/filesystems/proc.html

VIR_NODE_CPU_STATS_KERNEL = (system + irq + softirq)
VIR_NODE_CPU_STATS_USER   = (user + nice)
VIR_NODE_CPU_STATS_IDLE   = idle

<VIR_NODE_CPU_STATS_INTR> = N/A, irq is accounted by libvirt as KERNEL

VIR_NODE_CPU_STATS_IOWAIT = iowait
VIR_NODE_CPU_STATS_GUEST  = guest

VIR_NODE_CPU_STATS_GUEST was introduced in: b5878727c714
("util: virHostCPUGetStatsLinux: support VIR_NODE_CPU_STATS_GUEST")

with the goal of specifically accounting the CPU time spent running guest VCPUs.
Unfortunately at the time it was not considered that to get a measure of this
time, "guest" is not sufficient, because any guest that is "niced" is accounted
in a separate category, "guest_nice".

This patch rectifies the situation by adding the guest_nice counter, so that

VIR_NODE_CPU_STATS_GUEST = (guest + guest_nice)

which makes the statistic useful to the caller, as the totals sum up correctly.

In order to find the total USER time spent running host tasks, for example:

cpu_user_host = VIR_NODE_CPU_STATS_USER - VIR_NODE_CPU_STATS_GUEST

this follows from the fact that "guest" is included in "user" accounting,
and "guest_nice" is included in "nice" accounting.

Extend the existing tests artificially to capture this specific case.

Fixes: b5878727c714d813c820ad4a1b695fbbb5ffc84e
Signed-off-by: Claudio Fontana <cfontana@suse.de>
---
 src/util/virhostcpu.c                         | 2 +-
 tests/virhostcpudata/linux-cpustat-24cpu.out  | 8 ++++----
 tests/virhostcpudata/linux-cpustat-24cpu.stat | 4 ++--
 3 files changed, 7 insertions(+), 7 deletions(-)

diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
index 1db096ba24..f2b25e940b 100644
--- a/src/util/virhostcpu.c
+++ b/src/util/virhostcpu.c
@@ -882,7 +882,7 @@ virHostCPUGetStatsLinux(FILE *procstat,
                 return -1;
 
             if (virHostCPUStatsAssign(&params[4], VIR_NODE_CPU_STATS_GUEST,
-                                      guest * TICK_TO_NSEC) < 0)
+                                      (guest + guest_nice) * TICK_TO_NSEC) < 0)
                 return -1;
             return 0;
         }
diff --git a/tests/virhostcpudata/linux-cpustat-24cpu.out b/tests/virhostcpudata/linux-cpustat-24cpu.out
index f3183f5c41..a975702a06 100644
--- a/tests/virhostcpudata/linux-cpustat-24cpu.out
+++ b/tests/virhostcpudata/linux-cpustat-24cpu.out
@@ -1,16 +1,16 @@
 cpu:
 kernel: 8751170
 user: 14128079
-idle: 1816344522
+idle: 1816344521
 iowait: 81323
-guest: 5880634
+guest: 5880635
 
 cpu0:
 kernel: 447603
 user: 749021
-idle: 75399242
+idle: 75399241
 iowait: 5295
-guest: 331814
+guest: 331815
 
 cpu1:
 kernel: 167215
diff --git a/tests/virhostcpudata/linux-cpustat-24cpu.stat b/tests/virhostcpudata/linux-cpustat-24cpu.stat
index bc9d449e1c..e13035b5f0 100644
--- a/tests/virhostcpudata/linux-cpustat-24cpu.stat
+++ b/tests/virhostcpudata/linux-cpustat-24cpu.stat
@@ -1,5 +1,5 @@
-cpu  14126233 1846 7764352 1816344522 81323 395581 591237 0 5880634 0
-cpu0 748997 24 320851 75399242 5295 22050 104702 0 331814 0
+cpu  14126233 1846 7764352 1816344521 81323 395581 591237 0 5880634 1
+cpu0 748997 24 320851 75399241 5295 22050 104702 0 331814 1
 cpu1 337325 1 140909 76178612 1121 8962 17344 0 166726 0
 cpu2 666860 29 269302 75649696 4298 18473 21155 0 272094 0
 cpu3 328387 77 211400 76131634 1219 9701 6573 0 115551 0
-- 
2.35.3
Re: [PATCH v2] util: virHostCPUGetStatsLinux: add guest_nice to VIR_NODE_CPU_STATS_GUEST
Posted by Claudio Fontana 2 days, 5 hours ago 
Hello Peter, Daniel,

is this new commit message better?

Thanks,

Claudio

On 6/17/26 18:14, Claudio Fontana wrote:
> On Linux the accounting stats come from /proc/stat entries and the mapping is:
> 
> https://www.kernel.org/doc/html/latest/filesystems/proc.html
> 
> VIR_NODE_CPU_STATS_KERNEL = (system + irq + softirq)
> VIR_NODE_CPU_STATS_USER   = (user + nice)
> VIR_NODE_CPU_STATS_IDLE   = idle
> 
> <VIR_NODE_CPU_STATS_INTR> = N/A, irq is accounted by libvirt as KERNEL
> 
> VIR_NODE_CPU_STATS_IOWAIT = iowait
> VIR_NODE_CPU_STATS_GUEST  = guest
> 
> VIR_NODE_CPU_STATS_GUEST was introduced in: b5878727c714
> ("util: virHostCPUGetStatsLinux: support VIR_NODE_CPU_STATS_GUEST")
> 
> with the goal of specifically accounting the CPU time spent running guest VCPUs.
> Unfortunately at the time it was not considered that to get a measure of this
> time, "guest" is not sufficient, because any guest that is "niced" is accounted
> in a separate category, "guest_nice".
> 
> This patch rectifies the situation by adding the guest_nice counter, so that
> 
> VIR_NODE_CPU_STATS_GUEST = (guest + guest_nice)
> 
> which makes the statistic useful to the caller, as the totals sum up correctly.
> 
> In order to find the total USER time spent running host tasks, for example:
> 
> cpu_user_host = VIR_NODE_CPU_STATS_USER - VIR_NODE_CPU_STATS_GUEST
> 
> this follows from the fact that "guest" is included in "user" accounting,
> and "guest_nice" is included in "nice" accounting.
> 
> Extend the existing tests artificially to capture this specific case.
> 
> Fixes: b5878727c714d813c820ad4a1b695fbbb5ffc84e
> Signed-off-by: Claudio Fontana <cfontana@suse.de>
> ---
>  src/util/virhostcpu.c                         | 2 +-
>  tests/virhostcpudata/linux-cpustat-24cpu.out  | 8 ++++----
>  tests/virhostcpudata/linux-cpustat-24cpu.stat | 4 ++--
>  3 files changed, 7 insertions(+), 7 deletions(-)
> 
> diff --git a/src/util/virhostcpu.c b/src/util/virhostcpu.c
> index 1db096ba24..f2b25e940b 100644
> --- a/src/util/virhostcpu.c
> +++ b/src/util/virhostcpu.c
> @@ -882,7 +882,7 @@ virHostCPUGetStatsLinux(FILE *procstat,
>                  return -1;
>  
>              if (virHostCPUStatsAssign(&params[4], VIR_NODE_CPU_STATS_GUEST,
> -                                      guest * TICK_TO_NSEC) < 0)
> +                                      (guest + guest_nice) * TICK_TO_NSEC) < 0)
>                  return -1;
>              return 0;
>          }
> diff --git a/tests/virhostcpudata/linux-cpustat-24cpu.out b/tests/virhostcpudata/linux-cpustat-24cpu.out
> index f3183f5c41..a975702a06 100644
> --- a/tests/virhostcpudata/linux-cpustat-24cpu.out
> +++ b/tests/virhostcpudata/linux-cpustat-24cpu.out
> @@ -1,16 +1,16 @@
>  cpu:
>  kernel: 8751170
>  user: 14128079
> -idle: 1816344522
> +idle: 1816344521
>  iowait: 81323
> -guest: 5880634
> +guest: 5880635
>  
>  cpu0:
>  kernel: 447603
>  user: 749021
> -idle: 75399242
> +idle: 75399241
>  iowait: 5295
> -guest: 331814
> +guest: 331815
>  
>  cpu1:
>  kernel: 167215
> diff --git a/tests/virhostcpudata/linux-cpustat-24cpu.stat b/tests/virhostcpudata/linux-cpustat-24cpu.stat
> index bc9d449e1c..e13035b5f0 100644
> --- a/tests/virhostcpudata/linux-cpustat-24cpu.stat
> +++ b/tests/virhostcpudata/linux-cpustat-24cpu.stat
> @@ -1,5 +1,5 @@
> -cpu  14126233 1846 7764352 1816344522 81323 395581 591237 0 5880634 0
> -cpu0 748997 24 320851 75399242 5295 22050 104702 0 331814 0
> +cpu  14126233 1846 7764352 1816344521 81323 395581 591237 0 5880634 1
> +cpu0 748997 24 320851 75399241 5295 22050 104702 0 331814 1
>  cpu1 337325 1 140909 76178612 1121 8962 17344 0 166726 0
>  cpu2 666860 29 269302 75649696 4298 18473 21155 0 272094 0
>  cpu3 328387 77 211400 76131634 1219 9701 6573 0 115551 0
Re: [PATCH v2] util: virHostCPUGetStatsLinux: add guest_nice to VIR_NODE_CPU_STATS_GUEST
Posted by Peter Krempa via Devel 2 days, 5 hours ago 
On Mon, Jun 22, 2026 at 16:32:52 +0200, Claudio Fontana wrote:
> Hello Peter, Daniel,
> 
> is this new commit message better?

Looks better,

> 
> Thanks,
> 
> Claudio
> 
> On 6/17/26 18:14, Claudio Fontana wrote:
> > On Linux the accounting stats come from /proc/stat entries and the mapping is:
> > 
> > https://www.kernel.org/doc/html/latest/filesystems/proc.html
> > 
> > VIR_NODE_CPU_STATS_KERNEL = (system + irq + softirq)
> > VIR_NODE_CPU_STATS_USER   = (user + nice)
> > VIR_NODE_CPU_STATS_IDLE   = idle
> > 
> > <VIR_NODE_CPU_STATS_INTR> = N/A, irq is accounted by libvirt as KERNEL
> > 
> > VIR_NODE_CPU_STATS_IOWAIT = iowait
> > VIR_NODE_CPU_STATS_GUEST  = guest
> > 
> > VIR_NODE_CPU_STATS_GUEST was introduced in: b5878727c714
> > ("util: virHostCPUGetStatsLinux: support VIR_NODE_CPU_STATS_GUEST")
> > 
> > with the goal of specifically accounting the CPU time spent running guest VCPUs.
> > Unfortunately at the time it was not considered that to get a measure of this
> > time, "guest" is not sufficient, because any guest that is "niced" is accounted
> > in a separate category, "guest_nice".
> > 
> > This patch rectifies the situation by adding the guest_nice counter, so that
> > 
> > VIR_NODE_CPU_STATS_GUEST = (guest + guest_nice)
> > 
> > which makes the statistic useful to the caller, as the totals sum up correctly.
> > 
> > In order to find the total USER time spent running host tasks, for example:
> > 
> > cpu_user_host = VIR_NODE_CPU_STATS_USER - VIR_NODE_CPU_STATS_GUEST
> > 
> > this follows from the fact that "guest" is included in "user" accounting,
> > and "guest_nice" is included in "nice" accounting.
> > 
> > Extend the existing tests artificially to capture this specific case.
> > 
> > Fixes: b5878727c714d813c820ad4a1b695fbbb5ffc84e
> > Signed-off-by: Claudio Fontana <cfontana@suse.de>
> > ---
> >  src/util/virhostcpu.c                         | 2 +-
> >  tests/virhostcpudata/linux-cpustat-24cpu.out  | 8 ++++----
> >  tests/virhostcpudata/linux-cpustat-24cpu.stat | 4 ++--
> >  3 files changed, 7 insertions(+), 7 deletions(-)

Reviewed-by: Peter Krempa <pkrempa@redhat.com>

and pushed.

Patchew 2.1-devel-ea86937

© 2016 - 2026 Red Hat, Inc.