projects / ipfire-2.x.git / blame
| Commit | Line | Data |
|---|---|---|
| 2cb7cef9 BS |
1 | From: Mark Langsdorf <mark.langsdorf@amd.com> |
| 2 | Subject: X86 powernow-k8 cpufreq: Get transition latency from acpi _PSS object | |
| 3 | References: bnc#464461 | |
| 4 | Patch-Mainline: not yet | |
| 5 | ||
| 6 | The ondemand kernel governor calculates the best sampling rate (how often | |
| 7 | to check for CPU load) from the CPU transition latency it gets from the | |
| 8 | low level cpufreq drivers. Powernow-k8 returned too high values resulting | |
| 9 | in poor performance. | |
| 10 | ||
| 11 | The transition latency returned from the ACPI _PSS object is also used by | |
| 12 | AMD's Windows PowerNow driver (thus should always be sane) and returns more | |
| 13 | exact values than the previous, algorithm to guess the transition latency. | |
| 14 | ||
| 15 | Signed-off-by: Thomas Renninger <trenn@suse.de> | |
| 16 | ||
| 17 | --- | |
| 18 | arch/x86/kernel/cpu/cpufreq/powernow-k8.c | 30 ++++++++++++++++++++++++------ | |
| 19 | 1 file changed, 24 insertions(+), 6 deletions(-) | |
| 20 | ||
| 21 | Index: linux-2.6.27/arch/x86/kernel/cpu/cpufreq/powernow-k8.c | |
| 22 | =================================================================== | |
| 23 | --- linux-2.6.27.orig/arch/x86/kernel/cpu/cpufreq/powernow-k8.c | |
| 24 | +++ linux-2.6.27/arch/x86/kernel/cpu/cpufreq/powernow-k8.c | |
| 25 | @@ -927,10 +927,23 @@ static void powernow_k8_cpu_exit_acpi(st | |
| 26 | acpi_processor_unregister_performance(&data->acpi_data, data->cpu); | |
| 27 | } | |
| 28 | ||
| 29 | +static int get_transition_latency(struct powernow_k8_data *data) | |
| 30 | +{ | |
| 31 | + int max_latency = 0; | |
| 32 | + int i; | |
| 33 | + for (i = 0; i < data->acpi_data.state_count; i++) { | |
| 34 | + int cur_latency = data->acpi_data.states[i].transition_latency | |
| 35 | + + data->acpi_data.states[i].bus_master_latency; | |
| 36 | + if (cur_latency > max_latency) | |
| 37 | + max_latency = cur_latency; | |
| 38 | + } | |
| 39 | + return max_latency; | |
| 40 | +} | |
| 41 | #else | |
| 42 | static int powernow_k8_cpu_init_acpi(struct powernow_k8_data *data) { return -ENODEV; } | |
| 43 | static void powernow_k8_cpu_exit_acpi(struct powernow_k8_data *data) { return; } | |
| 44 | static void powernow_k8_acpi_pst_values(struct powernow_k8_data *data, unsigned int index) { return; } | |
| 45 | +static int get_transition_latency(struct powernow_k8_data *data) { return 0; } | |
| 46 | #endif /* CONFIG_X86_POWERNOW_K8_ACPI */ | |
| 47 | ||
| 48 | /* Take a frequency, and issue the fid/vid transition command */ | |
| 49 | @@ -1030,6 +1043,7 @@ static int powernowk8_target(struct cpuf | |
| 50 | unsigned int newstate; | |
| 51 | int ret = -EIO; | |
| 52 | ||
| 53 | + | |
| 54 | if (!data) | |
| 55 | return -EINVAL; | |
| 56 | ||
| 57 | @@ -1161,7 +1175,16 @@ static int __cpuinit powernowk8_cpu_init | |
| 58 | kfree(data); | |
| 59 | return -ENODEV; | |
| 60 | } | |
| 61 | - } | |
| 62 | + /* Take a crude guess here. | |
| 63 | + * That guess was in microseconds, so multiply with 1000 */ | |
| 64 | + pol->cpuinfo.transition_latency = ( | |
| 65 | + ( (data->rvo + 8) * data->vstable * VST_UNITS_20US) + | |
| 66 | + ( (1 << data->irt) * 30) | |
| 67 | + ) * 1000; | |
| 68 | + } | |
| 69 | + else /* ACPI _PSS objects available */ | |
| 70 | + pol->cpuinfo.transition_latency = | |
| 71 | + get_transition_latency(data) * 1000; | |
| 72 | ||
| 73 | /* only run on specific CPU from here on */ | |
| 74 | oldmask = current->cpus_allowed; | |
| 75 | @@ -1192,11 +1215,6 @@ static int __cpuinit powernowk8_cpu_init | |
| 76 | pol->cpus = per_cpu(cpu_core_map, pol->cpu); | |
| 77 | data->available_cores = &(pol->cpus); | |
| 78 | ||
| 79 | - /* Take a crude guess here. | |
| 80 | - * That guess was in microseconds, so multiply with 1000 */ | |
| 81 | - pol->cpuinfo.transition_latency = (((data->rvo + 8) * data->vstable * VST_UNITS_20US) | |
| 82 | - + (3 * (1 << data->irt) * 10)) * 1000; | |
| 83 | - | |
| 84 | if (cpu_family == CPU_HW_PSTATE) | |
| 85 | pol->cur = find_khz_freq_from_pstate(data->powernow_table, data->currpstate); | |
| 86 | else |