From: Penny Zheng <penny.zh...@amd.com>
The amd-cppc driver may support multiple working modes, passive and active.
Introduce `active` tag for users to explicitly select active mode and a new
variable `opt_cpufreq_active` to keep track of which mode is currently enabled.
Specific implementation will be introduced in the following commits.
Signed-off-by: Penny Zheng <penny.zh...@amd.com>
---
v1 -> v2:
- Remove pointless initializer
- Move driver registration change to the next commit
---
docs/misc/xen-command-line.pandoc | 8 +++++++-
xen/arch/x86/acpi/cpufreq/amd-cppc.c | 9 +++++++++
2 files changed, 16 insertions(+), 1 deletion(-)
diff --git a/docs/misc/xen-command-line.pandoc
b/docs/misc/xen-command-line.pandoc
index 78cfb8a02e..13f650270d 100644
--- a/docs/misc/xen-command-line.pandoc
+++ b/docs/misc/xen-command-line.pandoc
@@ -515,7 +515,7 @@ If set, force use of the performance counters for oprofile,
rather than detectin
available support.
### cpufreq
-> `= none | {{ <boolean> | xen } {
[:[powersave|performance|ondemand|userspace][,[<maxfreq>]][,[<minfreq>]]] }
[,verbose]} | dom0-kernel | hwp[:[<hdc>][,verbose]] | amd-cppc[:[verbose]]`
+> `= none | {{ <boolean> | xen } {
[:[powersave|performance|ondemand|userspace][,[<maxfreq>]][,[<minfreq>]]] }
[,verbose]} | dom0-kernel | hwp[:[<hdc>][,verbose]] |
amd-cppc[:[active][,verbose]]`
> Default: `xen`
@@ -538,6 +538,12 @@ choice of `dom0-kernel` is deprecated and not supported by
all Dom0 kernels.
on supported AMD hardware to provide finer grained frequency control
mechanism.
The default is disabled. If `amd-cppc` is selected, but hardware support
is not available, Xen will fallback to cpufreq=xen.
+* `active` is a boolean to enable amd-cppc driver in active(autonomous) mode.
+ In this mode, users could provide a hint with energy performance preference
+ register to the hardware if they want to bias toward performance(0x0) or
+ energy efficiency(0xff), then CPPC power algorithm will calculate the runtime
+ workload and adjust the realtime cores frequency according to the power
supply
+ and thermal, core voltage and some other hardware conditions.
There is also support for `;`-separated fallback options:
`cpufreq=hwp;xen,verbose`. This first tries `hwp` and falls back to `xen` if
diff --git a/xen/arch/x86/acpi/cpufreq/amd-cppc.c
b/xen/arch/x86/acpi/cpufreq/amd-cppc.c
index f14e7a6638..1742c57170 100644
--- a/xen/arch/x86/acpi/cpufreq/amd-cppc.c
+++ b/xen/arch/x86/acpi/cpufreq/amd-cppc.c
@@ -33,6 +33,8 @@
#define amd_cppc_warn(fmt, args...) \
printk(XENLOG_WARNING "AMD_CPPC: CPU%u warning: " fmt, cpu, ## args)
+static bool __ro_after_init opt_cpufreq_active;
+
struct amd_cppc_drv_data
{
struct xen_processor_cppc *cppc_data;
@@ -80,6 +82,13 @@ static bool __init amd_cppc_handle_option(const char *s,
const char *end)
return true;
}
+ ret = parse_boolean("active", s, end);
+ if ( ret >= 0 )
+ {
+ opt_cpufreq_active = ret;
+ return true;
+ }
+
return false;
}
--
2.34.1
