linux.git/drivers/cpufreq/intel_pstate.c, branch v3.14

intel_pstate: Change busy calculation to use fixed point math.

2014-02-25T23:56:49+00:00

Commit fcb6a15c2e (intel_pstate: Take core C0 time into account for
core busy calculation) introduced a regression on some processor SKUs
supported by intel_pstate. This was due to the truncation caused by
using integer math to calculate core busy and C0 percentages.

On a i7-4770K processor operating at 800Mhz going to 100% utilization
the percent busy of the CPU using integer math is 22%, but it actually
is 22.85%.  This value scaled to the current frequency returned 97
which the PID interpreted as no error and did not adjust the P state.

Tested on i7-4770K, i7-2600, i5-3230M.

Fixes: fcb6a15c2e7e (intel_pstate: Take core C0 time into account for core busy calculation)
References: https://lkml.org/lkml/2014/2/19/626
References: https://bugzilla.kernel.org/show_bug.cgi?id=70941
Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Add support for Baytrail turbo P states

2014-02-21T00:22:40+00:00

A documentation update exposed the existance of the turbo ratio
register. Update baytrail support to use the turbo range.

Signed-off-by: Dirk Brandewie 
Cc: 3.13+  # 3.13+
Signed-off-by: Rafael J. Wysocki

intel_pstate: Use LFM bus ratio as min ratio/P state

2014-02-21T00:22:40+00:00

LFM (max efficiency ratio) is the max frequency at minimum voltage
supported by the processor.  Using LFM as the minimum P state
increases performmance without affecting power. By not using P states
below LFM we avoid using P states that are less power efficient.

Signed-off-by: Dirk Brandewie 
Cc: 3.13+  # 3.13+
Signed-off-by: Rafael J. Wysocki

intel_pstate: Remove energy reporting from pstate_sample tracepoint

2014-02-13T01:11:18+00:00

Remove the reporting of energy since it does not provide any useful
information about the state of the driver and will be a maintainance
headache going forward since the RAPL energy units register is not
architectural and subject to change between micro-architectures

References: https://bugzilla.kernel.org/show_bug.cgi?id=69831
Fixes: b69880f9ccf7 (intel_pstate: Add trace point to report internal state.)
Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Take core C0 time into account for core busy calculation

2014-02-04T20:41:15+00:00

Take non-idle time into account when calculating core busy time.
This ensures that intel_pstate will notice a decrease in load.

References: https://bugzilla.kernel.org/show_bug.cgi?id=66581
Cc: 3.10+  # 3.10+
Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

intel_pstate: Add trace point to report internal state.

2014-01-17T01:00:44+00:00

Add perf trace event "power:pstate_sample" to report driver state to
aid in diagnosing issues reported against intel_pstate.

Signed-off-by: Dirk Brandewie 
Signed-off-by: Rafael J. Wysocki

Merge back earlier 'pm-cpufreq' material.

2014-01-14T22:12:08+00:00

intel_pstate: Add X86_FEATURE_APERFMPERF to cpu match parameters.

2014-01-06T21:16:14+00:00

KVM environments do not support APERF/MPERF MSRs. intel_pstate cannot
operate without these registers.

The previous validity checks in intel_pstate_msrs_not_valid() are
insufficent in nested KVMs.

References: https://bugzilla.redhat.com/show_bug.cgi?id=1046317
Signed-off-by: Dirk Brandewie 
Cc: All applicable 
Signed-off-by: Rafael J. Wysocki

Merge back earlier 'pm-cpufreq' material.

2014-01-05T14:32:51+00:00

intel_pstate: Fail initialization if P-state information is missing

2013-12-31T12:37:46+00:00

If pstate.current_pstate is 0 after the initial
intel_pstate_get_cpu_pstates(), this means that we were unable to
obtain any useful P-state information and there is no reason to
continue, so free memory and return an error in that case.

This fixes the following divide error occuring in a nested KVM
guest:

Intel P-state driver initializing.
Intel pstate controlling: cpu 0
cpufreq: __cpufreq_add_dev: ->get() failed
divide error: 0000 [#1] SMP
Modules linked in:
CPU: 0 PID: 1 Comm: swapper/0 Not tainted 3.13.0-0.rc4.git5.1.fc21.x86_64 #1
Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011
task: ffff88001ea20000 ti: ffff88001e9bc000 task.ti: ffff88001e9bc000
RIP: 0010:[]  [] intel_pstate_timer_func+0x11d/0x2b0
RSP: 0000:ffff88001ee03e18  EFLAGS: 00010246
RAX: 0000000000000000 RBX: ffff88001a454348 RCX: 0000000000006100
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffff88001ee03e38 R08: 0000000000000000 R09: 0000000000000000
R10: ffff88001ea20000 R11: 0000000000000000 R12: 00000c0a1ea20000
R13: 1ea200001ea20000 R14: ffffffff815c5400 R15: ffff88001a454348
FS:  0000000000000000(0000) GS:ffff88001ee00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 000000008005003b
CR2: 0000000000000000 CR3: 0000000001c0c000 CR4: 00000000000006f0
Stack:
 fffffffb1a454390 ffffffff821a4500 ffff88001a454390 0000000000000100
 ffff88001ee03ea8 ffffffff81083e9a ffffffff81083e15 ffffffff82d5ed40
 ffffffff8258cc60 0000000000000000 ffffffff81ac39de 0000000000000000
Call Trace:
 
 [] call_timer_fn+0x8a/0x310
 [] ? call_timer_fn+0x5/0x310
 [] ? pid_param_set+0x130/0x130
 [] run_timer_softirq+0x234/0x380
 [] __do_softirq+0x104/0x430
 [] irq_exit+0xcd/0xe0
 [] smp_apic_timer_interrupt+0x45/0x60
 [] apic_timer_interrupt+0x72/0x80
 
 [] ? vprintk_emit+0x1dd/0x5e0
 [] printk+0x67/0x69
 [] __cpufreq_add_dev.isra.13+0x883/0x8d0
 [] cpufreq_add_dev+0x10/0x20
 [] subsys_interface_register+0xb1/0xf0
 [] cpufreq_register_driver+0x9f/0x210
 [] intel_pstate_init+0x27d/0x3be
 [] ? mutex_unlock+0xe/0x10
 [] ? cpufreq_gov_dbs_init+0x12/0x12
 [] do_one_initcall+0xfa/0x1b0
 [] ? parse_args+0x225/0x3f0
 [] kernel_init_freeable+0x1fc/0x287
 [] ? do_early_param+0x88/0x88
 [] ? rest_init+0x150/0x150
 [] kernel_init+0xe/0x130
 [] ret_from_fork+0x7c/0xb0
 [] ? rest_init+0x150/0x150
Code: c1 e0 05 48 63 bc 03 10 01 00 00 48 63 83 d0 00 00 00 48 63 d6 48 c1 e2 08 c1 e1 08 4c 63 c2 48 c1 e0 08 48 98 48 c1 e0 08 48 99 <49> f7 f8 48 98 48 0f af f8 48 c1 ff 08 29 f9 89 ca c1 fa 1f 89
RIP  [] intel_pstate_timer_func+0x11d/0x2b0
 RSP 
---[ end trace f166110ed22cc37a ]---
Kernel panic - not syncing: Fatal exception in interrupt

Reported-and-tested-by: Kashyap Chamarthy 
Cc: Josh Boyer 
Signed-off-by: Rafael J. Wysocki 
Cc: All applicable