On Wed, 2010-03-03 at 23:48 +0530, Vaidyanathan Srinivasan wrote:
> Hi,
> diff --git a/arch/powerpc/kernel/setup-common.c
> b/arch/powerpc/kernel/setup-common.c
> index 03dd6a2..fbd93e3 100644
> --- a/arch/powerpc/kernel/setup-common.c
> +++ b/arch/powerpc/kernel/setup-common.c
> @@ -359,6 +359,8 @@ void __init check_for_initrd(void)
> #ifdef CONFIG_SMP
>
> int threads_per_core, threads_shift;
> +EXPORT_SYMBOL_GPL(threads_per_core);
While I agree it should be exported for the APIs in cputhread.h to be
usable from a module, this variable shouldn't be -used- directly, but
only via the API functions in there.
.../...
> +
> +#define MODULE_VERS "1.0"
> +#define MODULE_NAME "pseries_energy"
> +
> +/* Helper Routines to convert between drc_index to cpu numbers */
> +
> +static u32 cpu_to_drc_index(int cpu)
> +{
> + struct device_node *dn = NULL;
> + const int *indexes;
> + int i;
> + dn = of_find_node_by_name(dn, "cpus");
Check the result. Also that's not a nice way to do that, you should look
for /cpus by path I reckon.
> + indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
Check the result here too.
> + /* Convert logical cpu number to core number */
> + i = cpu / threads_per_core;
Don't use that variable as I said earlier. Use cpu_thread_to_core()
> + /*
> + * The first element indexes[0] is the number of drc_indexes
> + * returned in the list. Hence i+1 will get the drc_index
> + * corresponding to core number i.
> + */
> + WARN_ON(i > indexes[0]);
> + return indexes[i + 1];
> +}
> +
> +static int drc_index_to_cpu(u32 drc_index)
> +{
> + struct device_node *dn = NULL;
> + const int *indexes;
> + int i, cpu;
> + dn = of_find_node_by_name(dn, "cpus");
> + indexes = of_get_property(dn, "ibm,drc-indexes", NULL);
Same comments, check results and use /cpus path
> + /*
> + * First element in the array is the number of drc_indexes
> + * returned. Search through the list to find the matching
> + * drc_index and get the core number
> + */
> + for (i = 0; i < indexes[0]; i++) {
> + if (indexes[i + 1] == drc_index)
> + break;
> + }
> + /* Convert core number to logical cpu number */
> + cpu = i * threads_per_core;
Here's more annoying as we don't have an API in cputhread.h for that.
In fact, we have a confusion in there since cpu_first_thread_in_core()
doesn't actually take a core number ...
I'm going to recommend a complicated approach but that's the best in the
long run:
- First do a patch that renames cpu_first_thread_in_core() to something
clearer like cpu_first_thread_in_same_core() or cpu_leftmost_sibling()
(I think I prefer the later). Rename the few users in
arch/powerpc/mm/mmu_context_nohash.c and arch/powerpc/kernel/smp.c
- Then do a patch that adds a cpu_first_thread_of_core() that takes a
core number, basically does:
static inline int cpu_first_thread_of_core(int core)
{
return core << threads_shift;
}
- Then add your modified H_BEST_ENERGY patch on top of it using the
above two as pre-reqs :-)
> + return cpu;
> +}
> +
> +/*
> + * pseries hypervisor call H_BEST_ENERGY provides hints to OS on
> + * preferred logical cpus to activate or deactivate for optimized
> + * energy consumption.
> + */
> +
> +#define FLAGS_MODE1 0x004E200000080E01
> +#define FLAGS_MODE2 0x004E200000080401
> +#define FLAGS_ACTIVATE 0x100
> +
> +static ssize_t get_best_energy_list(char *page, int activate)
> +{
> + int rc, cnt, i, cpu;
> + unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
> + unsigned long flags = 0;
> + u32 *buf_page;
> + char *s = page;
> +
> + buf_page = (u32 *) get_zeroed_page(GFP_KERNEL);
> +
Why that blank line ?
> + if (!buf_page)
> + return 0;
So here you return 0 instead of -ENOMEM
> + flags = FLAGS_MODE1;
> + if (activate)
> + flags |= FLAGS_ACTIVATE;
> +
> + rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags, 0, __pa(buf_page),
> + 0, 0, 0, 0, 0, 0);
> +
> +
Again, no need for a blank line before xx = foo() and if (xx)
> if (rc != H_SUCCESS) {
> + free_page((unsigned long) buf_page);
> + return -EINVAL;
> + }
And here you return an error code. Which one is right ?
> + cnt = retbuf[0];
> + for (i = 0; i < cnt; i++) {
> + cpu = drc_index_to_cpu(buf_page[2*i+1]);
> + if ((cpu_online(cpu) && !activate) ||
> + (!cpu_online(cpu) && activate))
> + s += sprintf(s, "%d,", cpu);
> + }
> + if (s > page) { /* Something to show */
> + s--; /* Suppress last comma */
> + s += sprintf(s, "\n");
> + }
> +
> + free_page((unsigned long) buf_page);
> + return s-page;
> +}
> +
> +static ssize_t get_best_energy_data(struct sys_device *dev,
> + char *page, int activate)
> +{
> + int rc;
> + unsigned long retbuf[PLPAR_HCALL9_BUFSIZE];
> + unsigned long flags = 0;
> +
> + flags = FLAGS_MODE2;
> + if (activate)
> + flags |= FLAGS_ACTIVATE;
> +
> + rc = plpar_hcall9(H_BEST_ENERGY, retbuf, flags,
> + cpu_to_drc_index(dev->id),
> + 0, 0, 0, 0, 0, 0, 0);
> +
> + if (rc != H_SUCCESS)
> + return -EINVAL;
> +
> + return sprintf(page, "%lu\n", retbuf[1] >> 32);
> +}
> +
> +/* Wrapper functions */
> +
> +static ssize_t cpu_activate_hint_list_show(struct sysdev_class *class,
> + char *page)
> +{
> + return get_best_energy_list(page, 1);
> +}
> +
> +static ssize_t cpu_deactivate_hint_list_show(struct sysdev_class *class,
> + char *page)
> +{
> + return get_best_energy_list(page, 0);
> +}
> +
> +static ssize_t percpu_activate_hint_show(struct sys_device *dev,
> + struct sysdev_attribute *attr, char *page)
> +{
> + return get_best_energy_data(dev, page, 1);
> +}
> +
> +static ssize_t percpu_deactivate_hint_show(struct sys_device *dev,
> + struct sysdev_attribute *attr, char *page)
> +{
> + return get_best_energy_data(dev, page, 0);
> +}
> +
> +/*
> + * Create sysfs interface:
> + * /sys/devices/system/cpu/pseries_activate_hint_list
> + * /sys/devices/system/cpu/pseries_deactivate_hint_list
> + * Comma separated list of cpus to activate or deactivate
> + * /sys/devices/system/cpu/cpuN/pseries_activate_hint
> + * /sys/devices/system/cpu/cpuN/pseries_deactivate_hint
> + * Per-cpu value of the hint
> + */
> +
> +struct sysdev_class_attribute attr_cpu_activate_hint_list =
> + _SYSDEV_CLASS_ATTR(pseries_activate_hint_list, 0444,
> + cpu_activate_hint_list_show, NULL);
> +
> +struct sysdev_class_attribute attr_cpu_deactivate_hint_list =
> + _SYSDEV_CLASS_ATTR(pseries_deactivate_hint_list, 0444,
> + cpu_deactivate_hint_list_show, NULL);
> +
> +struct sysdev_attribute attr_percpu_activate_hint =
> + _SYSDEV_ATTR(pseries_activate_hint, 0444,
> + percpu_activate_hint_show, NULL);
> +
> +struct sysdev_attribute attr_percpu_deactivate_hint =
> + _SYSDEV_ATTR(pseries_deactivate_hint, 0444,
> + percpu_deactivate_hint_show, NULL);
> +
> +static int __init pseries_energy_init(void)
> +{
> + int cpu, err;
> + struct sys_device *cpu_sys_dev;
> +
> + /* Create the sysfs files */
> + err = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
> + &attr_cpu_activate_hint_list.attr);
> + if (!err)
> + err = sysfs_create_file(&cpu_sysdev_class.kset.kobj,
> + &attr_cpu_deactivate_hint_list.attr);
> +
> + for_each_possible_cpu(cpu) {
> + cpu_sys_dev = get_cpu_sysdev(cpu);
> + err = sysfs_create_file(&cpu_sys_dev->kobj,
> + &attr_percpu_activate_hint.attr);
> + if (err)
> + break;
> + err = sysfs_create_file(&cpu_sys_dev->kobj,
> + &attr_percpu_deactivate_hint.attr);
> + if (err)
> + break;
> + }
> + return err;
> +
> +}
> +
> +static void __exit pseries_energy_cleanup(void)
> +{
> + int cpu;
> + struct sys_device *cpu_sys_dev;
> +
> + /* Remove the sysfs files */
> + sysfs_remove_file(&cpu_sysdev_class.kset.kobj,
> + &attr_cpu_activate_hint_list.attr);
> +
> + sysfs_remove_file(&cpu_sysdev_class.kset.kobj,
> + &attr_cpu_deactivate_hint_list.attr);
> +
> + for_each_possible_cpu(cpu) {
> + cpu_sys_dev = get_cpu_sysdev(cpu);
> + sysfs_remove_file(&cpu_sys_dev->kobj,
> + &attr_percpu_activate_hint.attr);
> + sysfs_remove_file(&cpu_sys_dev->kobj,
> + &attr_percpu_deactivate_hint.attr);
> + }
> +}
> +
> +module_init(pseries_energy_init);
> +module_exit(pseries_energy_cleanup);
> +MODULE_DESCRIPTION("Driver for pseries platform energy management");
> +MODULE_AUTHOR("Vaidyanathan Srinivasan");
> +MODULE_LICENSE("GPL");
>
Cheers,
Ben.
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