Re: [PATCH 2/2 V7] intel_pstate: add kernel parameter to force loading on Sun X86 servers.

From: ethan zhao
Date: Thu Dec 04 2014 - 21:14:28 EST


On 2014/12/5 6:10, Rafael J. Wysocki wrote:
On Thursday, December 04, 2014 11:07:31 AM Ethan Zhao wrote:
To force loading on Oracle Sun X86 servers, provide one kernel command line

intel_pstate = ora_force
I would suggest to change the name of the option to "oracle_force" or "sun_force"
for clarity.

Anyway, I need an ACK from Kristen if this patch is to be applied.
"oracle_force" or "sun_force" doesn't sound bad to me, except it looks like a suggestion from
"Oracle" or "Sun". does it imply user to use it by default on Oracle boxes ?

For those who be aware of the risk of no power capping capabily working and
try to get better performance with this driver.

Signed-off-by: Ethan Zhao <ethan.zhao@xxxxxxxxxx>
v2: change to hardware vendor specific naming parameter.
v4: refine code and doc.
v5&v6: fix a typo in doc.
v7: change enum PCC to PPC.

Documentation/kernel-parameters.txt | 5 +++++
drivers/cpufreq/intel_pstate.c | 6 +++++-
2 files changed, 10 insertions(+), 1 deletion(-)

diff --git a/Documentation/kernel-parameters.txt b/Documentation/kernel-parameters.txt
index 479f332..7d0983e 100644
--- a/Documentation/kernel-parameters.txt
+++ b/Documentation/kernel-parameters.txt
@@ -1446,6 +1446,11 @@ bytes respectively. Such letter suffixes can also be entirely omitted.
Do not enable intel_pstate as the default
scaling driver for the supported processors
+ ora_force
+ Force loading intel_pstate on Oracle Sun Servers(X86).
+ only for those who be aware of the risk of no power capping
+ capability working and try to get better performance with this
+ driver.
That is not sufficiently clear. What does "risk of no power capping capability
working" mean, in particular?
That means we couldn't limit the power consumption of the host to what we want, in some cases, it
possibly burn the fuse if the redundancy of power supply is not enough, that would stop service.

Did I make it clear ?


intremap= [X86-64, Intel-IOMMU]
on enable Interrupt Remapping (default)
diff --git a/drivers/cpufreq/intel_pstate.c b/drivers/cpufreq/intel_pstate.c
index 1bb62ca..2654e13 100644
--- a/drivers/cpufreq/intel_pstate.c
+++ b/drivers/cpufreq/intel_pstate.c
@@ -866,6 +866,7 @@ static struct cpufreq_driver intel_pstate_driver = {
static int __initdata no_load;
+static unsigned int ora_force;
static int intel_pstate_msrs_not_valid(void)
@@ -1003,7 +1004,8 @@ static bool intel_pstate_platform_pwr_mgmt_exists(void)
case PSS:
return intel_pstate_no_acpi_pss();
case PPC:
- return intel_pstate_has_acpi_ppc();
+ return intel_pstate_has_acpi_ppc() &&
+ (!ora_force);
@@ -1078,6 +1080,8 @@ static int __init intel_pstate_setup(char *str)
if (!strcmp(str, "disable"))
no_load = 1;
+ if (!strcmp(str, "ora_force"))
+ ora_force = 1;
return 0;
early_param("intel_pstate", intel_pstate_setup);
And can anyone please remind me what was wrong with a "force" option that would
work for everyone, not just Oracle/Sun?

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