Hello,
I have a computer with an Intel i3-9100 CPU, using the integrated graphics, no graphic session running, and a monitor plugged in to the DVI port.
The following command executed upon startup:
setterm --term linux --blank 1
After one minute of console inactivity the monitor is actually suspended, and I get the following effect every ~20 seconds:
# turbostat --interval 1 --show PkgWatt,CorWatt,Avg_MHz,Busy%,Bzy_MHz,IPC,IRQ,CoreTmp,PkgTmp,POLL,POLL%
Avg_MHz Busy% Bzy_MHz IPC IRQ POLL POLL% CoreTmp PkgTmp PkgWatt CorWatt
2 0.20 800 0.38 57 0 0.00 31 31 0.35 0.11
1 0.11 800 0.22 9 0 0.00 30 31 0.35 0.11
2 0.28 800 0.26 16 0 0.00 30
1 0.08 800 0.30 8 0 0.00 31
3 0.34 800 0.55 24 0 0.00 31
Avg_MHz Busy% Bzy_MHz IPC IRQ POLL POLL% CoreTmp PkgTmp PkgWatt CorWatt
3233 81.25 3978 0.06 3782 142889 78.95 35 34 19.93 19.78
3396 85.32 3980 0.06 2731 36309 78.63 34 34 19.91 19.77
3171 79.77 3975 0.06 223 35550 79.02 32
3170 79.67 3979 0.06 212 35545 79.05 33
3191 80.23 3977 0.06 616 35485 79.01 35
Avg_MHz Busy% Bzy_MHz IPC IRQ POLL POLL% CoreTmp PkgTmp PkgWatt CorWatt
2 0.14 1397 0.31 57 0 0.00 32 32 0.38 0.13
1 0.08 1331 0.17 10 0 0.00 30 32 0.38 0.13
2 0.21 1142 0.22 16 0 0.00 30
1 0.05 2129 0.22 10 0 0.00 31
3 0.20 1494 0.47 21 0 0.00 32
Or, with .5 second interval:
Avg_MHz Busy% Bzy_MHz IPC IRQ POLL POLL% CoreTmp PkgTmp PkgWatt CorWatt
3 0.32 800 0.43 43 0 0.00 30 30 0.39 0.16
2 0.27 800 0.31 11 0 0.00 29 30 0.39 0.16
1 0.14 800 0.27 9 0 0.00 28
5 0.62 800 0.28 18 0 0.00 29
2 0.26 800 0.98 5 0 0.00 30
Avg_MHz Busy% Bzy_MHz IPC IRQ POLL POLL% CoreTmp PkgTmp PkgWatt CorWatt
1373 35.07 3912 0.06 752 31036 34.45 38 38 8.30 8.11
1370 34.97 3918 0.06 51 7723 34.44 38 38 8.29 8.10
1374 35.36 3886 0.06 533 7885 34.29 37
1372 35.06 3914 0.06 51 7719 34.48 37
1371 34.88 3932 0.06 117 7709 34.48 38
Avg_MHz Busy% Bzy_MHz IPC IRQ POLL POLL% CoreTmp PkgTmp PkgWatt CorWatt
3626 90.58 4003 0.06 2081 80119 88.33 39 39 21.97 21.82
3565 89.12 4000 0.06 120 19931 88.44 39 39 21.97 21.82
3788 94.46 4011 0.06 1503 20358 88.02 38
3565 89.13 4000 0.06 123 19930 88.43 39
3584 89.59 4001 0.06 335 19900 88.42 39
Avg_MHz Busy% Bzy_MHz IPC IRQ POLL POLL% CoreTmp PkgTmp PkgWatt CorWatt
1477 36.91 4003 0.06 987 31849 35.03 32 32 9.67 9.46
1417 35.45 3998 0.06 56 7922 35.11 30 32 9.67 9.47
1639 40.76 4022 0.06 705 8101 34.92 29
1420 35.54 3996 0.06 64 7920 35.09 30
1434 35.90 3994 0.06 162 7906 35.06 32
Avg_MHz Busy% Bzy_MHz IPC IRQ POLL POLL% CoreTmp PkgTmp PkgWatt CorWatt
2 0.23 925 0.46 22 0 0.00 30 30 0.36 0.11
2 0.16 1059 0.30 7 0 0.00 29 30 0.36 0.11
1 0.07 1036 0.30 2 0 0.00 29
4 0.47 867 0.26 12 0 0.00 30
2 0.20 911 1.09 1 0 0.00 30
Nothing is seen in `top`. I can see a brief ~20 watt increase in power consuption reported by the UPS.
There is no issue while the display is active.
If the monitor is unplugged these spikes occur every 20 seconds, even if no blanking/suspend is enabled.
As long as the monitor is plugged in, and the display is not suspended on the computer side, the issue doesn't occur even if the monitor is powered off.
With the i915 driver blacklisted the display can not be suspended, it is only blanked. The CPU spikes do not occur at all, whether the display is active, blanked or unplugged.
The behavior is the same with linux 6.1.85 from bookworm.
# dmesg | grep i915
[ 3.681513] i915 0000:00:02.0: [drm] VT-d active for gfx access
[ 3.681610] i915 0000:00:02.0: vgaarb: deactivate vga console
[ 3.681642] i915 0000:00:02.0: [drm] Using Transparent Hugepages
[ 3.682781] i915 0000:00:02.0: vgaarb: VGA decodes changed: olddecodes=io+mem,decodes=io+mem:owns=io+mem
[ 3.683974] i915 0000:00:02.0: firmware: direct-loading firmware i915/kbl_dmc_ver1_04.bin
[ 3.684936] i915 0000:00:02.0: [drm] Finished loading DMC firmware i915/kbl_dmc_ver1_04.bin (v1.4)
[ 4.092652] i915 0000:00:02.0: [drm] [ENCODER:94:DDI A/PHY A] failed to retrieve link info, disabling eDP
[ 4.118882] [drm] Initialized i915 1.6.0 20230929 for 0000:00:02.0 on minor 0
[ 4.121193] i915 display info: display version: 9
[ 4.121195] i915 display info: cursor_needs_physical: no
[ 4.121196] i915 display info: has_cdclk_crawl: no
[ 4.121197] i915 display info: has_cdclk_squash: no
[ 4.121197] i915 display info: has_ddi: yes
[ 4.121198] i915 display info: has_dp_mst: yes
[ 4.121199] i915 display info: has_dsb: no
[ 4.121200] i915 display info: has_fpga_dbg: yes
[ 4.121200] i915 display info: has_gmch: no
[ 4.121201] i915 display info: has_hotplug: yes
[ 4.121202] i915 display info: has_hti: no
[ 4.121203] i915 display info: has_ipc: yes
[ 4.121203] i915 display info: has_overlay: no
[ 4.121204] i915 display info: has_psr: yes
[ 4.121205] i915 display info: has_psr_hw_tracking: yes
[ 4.121205] i915 display info: overlay_needs_physical: no
[ 4.121206] i915 display info: supports_tv: no
[ 4.121207] i915 display info: has_hdcp: yes
[ 4.121208] i915 display info: has_dmc: yes
[ 4.121208] i915 display info: has_dsc: no
[ 4.575203] fbcon: i915drmfb (fb0) is primary device
[ 4.602129] i915 0000:00:02.0: [drm] fb0: i915drmfb frame buffer device