This commit cherry-picks commits from the mainline kernel to improve
Sapphire Rapids CPU support in the following components of the StarlingX
kernel: intel_idle, perf/x86/RAPL and powercap, and perf/x86/cstate.
(RAPL stands for "Running Average Power Limit", which is a CPU feature
for measuring and limiting power consumption.)
These improvements are required to support a new power metrics
application in StarlingX, which is intended to work with Sapphire Rapids
CPUs: https://opendev.org/starlingx/app-power-metrics
The following commits are cherry-picked as part of this effort, in
chronological order, organized by component:
=> intel_idle
* commit 9edf3c0ffef0
("intel_idle: add SPR support")
(v5.18-rc1~203^2~3^3~5)
* commit da0e58c038e6
("intel_idle: add 'preferred_cstates' module argument")
(v5.18-rc1~203^2~3^3~4)
* commit 3a9cf77b60dc
("intel_idle: add core C6 optimization for SPR")
(v5.18-rc1~203^2~3^3~3)
* commit 39c184a6a9a7
("intel_idle: Fix the 'preferred_cstates' module parameter")
(v5.18-rc5~22^2^2~1)
* commit 7eac3bd38d18
("intel_idle: Fix SPR C6 optimization")
(v5.18-rc5~22^2^2)
* commit 1548fac47a11
("intel_idle: make SPR C1 and C1E be independent")
(v6.0-rc1~184^2~2^2^2)
=> perf/x86/rapl + powercap
* commit ffb20c2e52e8
("perf/x86/rapl: Add msr mask support")
(v5.12-rc1~146^2~3)
* commit b6f78d3fba7f
("perf/x86/rapl: Only check lower 32bits for RAPL energy counters")
(v5.12-rc1~146^2~2)
* commit 838342a6d6b7
("perf/x86/rapl: Fix psys-energy event on Intel SPR platform")
(v5.12-rc1~146^2~1)
* commit 931da6a0de5d
("powercap: intel_rapl: support new layout of Psys PowerLimit Register
on SPR")
(v5.17-rc1~167^2^4^2~1)
* commit 80275ca9e525
("perf/x86/rapl: Use standard Energy Unit for SPR Dram RAPL domain")
(v6.1-rc4~3^2~3)
=> perf/x86/cstate
* commit 87bf399f86ec
("perf/x86/cstate: Add ICELAKE_X and ICELAKE_D support")
(v5.14-rc1~7^2~1)
* commit 528c9f1daf20
("perf/x86/cstate: Add SAPPHIRERAPIDS_X CPU support")
(v5.18-rc4~3^2)
The set of commits listed above is a reduced version of a slightly
larger superset of commits we had originally considered for
cherry-picking. We opted for the commits listed above to limit potential
impact on the StarlingX kernel by focusing on Sapphire Rapids support
and direct dependencies only.
We should note that we encountered a number of merge conflicts while
cherry-picking these commits; however, none of the merge conflict
resolutions required significantly altering the modifications made by
the original commits. The individual patch files denote the nature of
the merge conflicts.
Verification:
* The kernel recipes and all kernel modules were built from scratch with
this commit, using the following command in a StarlingX build
environment:
$ build-pkgs -c -p linux,linux-rt,bnxt-en,i40e,i40e-cvl-2.54,\
i40e-cvl-4.10,iavf,iavf-cvl-2.54,iavf-cvl-4.10,ice,ice-cvl-2.54,\
ice-cvl-4.10,igb-uio,iqvlinux,kmod-opae-fpga-driver,mlnx-ofed-kernel,\
octeon-ep,qat1.7.l
These packages were further packaged into a StarlingX (ostree) patch
for easier deployment.
* An Ansible-bootstrapped low-latency All-in-One simplex StarlingX
set-up was prepared on a server with a Sapphire Rapids CPU.
* The ostree patch was installed onto the server to start testing our
changes. The kernel was confirmed to boot up as expected.
* We enabled RAPL Psys domain reporting the server's BIOS (originally
disabled), and we also disabled the BIOS-enforced limit on the CPU
*package* C-states (originally set to C0/C1).
* We forcibly removed the "intel_idle.max_cstate=0" kernel command line
argument by modifying the sysinv daemon's Python source code on the
server (with a systemd service that bind-mounts a replacement *.py
file, to avoid another ostree patch). This was required to prevent the
intel_idle driver from disabling itself, so that we could confirm the
sanity of the cherry-picked commits.
* The following tests were carried out, first with the patched
preempt-rt kernel, and next with the original unpatched preempt-rt
kernel:
* Confirm that the intel_idle CPU idling driver is active:
$ cat /sys/devices/system/cpu/cpuidle/current_driver
* Confirm the CPU idling state names and parameters:
$ grep -s '^' \
/sys/devices/system/cpu/cpu0/cpuidle/state[0-9]*/\
{name,desc,time,latency,residency}
* Confirm that the RAPL/powercap and C-state related performance
monitor unit (PMU) counters are usable by the kernel and with perf:
$ sudo perf list
* Confirm that the CPU and package C-state residency counters are
working:
$ perf stat -a \
-e cstate_core/c1-residency/ -e cstate_core/c6-residency/ \
-e cstate_pkg/c2-residency/ -e cstate_pkg/c6-residency/ \
-- sleep 5
* Confirm that RAPL/powercap-related performance counters are working:
$ perf stat -a \
-e power/energy-pkg/ -e power/energy-ram/ -e power/energy-psys/ \
-- sleep 5
With the unpatched kernel, we observed that the intel_idle driver used
CPU idling information exposed by the ACPI tables, with the following
idle state names: POLL, C1_ACPI, C2_ACPI. With the patched kernel the
C-state tables embedded in the intel_idle driver were used as
expected, with the following idle state names: POLL, C1, C1E, C6.
With the unpatched kernel, we observed that the CPU/package C-state
residency counters were not detected, whereas they were detected with
the patched kernel, as expected.
With both the unpatched and the patched kernels, the RAPL/powercap
related performance counters were detected. We observed that the units
for the DRAM domain were incorrect for the unpatched kernel, which was
expected due to the lack of commit 80275ca9e525 ("perf/x86/rapl: Use
standard Energy Unit for SPR Dram RAPL domain").
* To confirm the sanity of our results acquired with the patched kernel
in the previous step, we also carried out the following experiment
with the v6.4.3-rt6 kernel available in the linux-yocto repository as
commit 917d160a84f6 ("Merge branch 'v6.4/standard/base' into
v6.4/standard/preempt-rt/base") in the "v6.4/standard/preempt-rt/base"
branch.
The "notification of death" StarlingX kernel patch was forward-ported
to the v6.4.3-rt6 kernel and the "kernel.sched_nr_migrate" sysctl was
reintroduced to make this kernel work with the aforementioned
Ansible-bootstrapped StarlingX system.
Furthermore, to ensure that the RAPL/powercap features are aligned to
the most recent mainline kernel version, we cherry-picked the
following commits from v6.5-rc1 onto the v6.4.3-rt6 kernel:
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/log/?qt=range&q=44c026a73be8..49776c712eb6
Afterwards, this v6.4.3-rt6-based test kernel was built and installed
onto the test server, and test procedures discussed in the previous
step were repeated.
Compared to the patched StarlingX v5.10 kernel, we observed that the
RAPL/powercap measurements were similar, and the CPU and package
C-state residency counters were not extremely different with the
v6.4.3-rt6-based test kernel.
* We should note that we have repeated tests with the patched StarlingX
v5.10 kernel as well, but we did not reinstall the system to acquire a
standard/non-low-latency set-up. Instead, we opted for running the
following command, rebooting the system into the standard kernel,
followed by repeating the test procedures, which had similar results.
sudo grub-editenv /boot/1/kernel.env set kernel=vmlinuz-5.10.0-6-amd64
Acknowledgements:
* Thanks to Alyson Deives Pereira for his extensive help in pruning the
commits that we had originally thought of cherry-picking with this
commit.
* Thanks to Mark Asselstine for his advice on the second phase of the
commit pruning activity.
Story: 2010773
Task: 48449
Change-Id: Ibe6bff65e8a415ac027a5d493a0e65fe58c9e344
Signed-off-by: M. Vefa Bicakci <vefa.bicakci@windriver.com>
0ee7813d66