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Message-Id: <57fc8253-c5c3-6103-77cd-34aa4ec250a3@linux.vnet.ibm.com>
Date: Thu, 28 Feb 2019 11:25:25 +0530
From: Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
To: Daniel Axtens <dja@...ens.net>, mpe@...erman.id.au
Cc: linux-kernel@...r.kernel.org, linuxppc-dev@...ts.ozlabs.org,
ego@...ux.vnet.ibm.com
Subject: Re: [PATCH] powernv: powercap: Add hard minimum powercap
Hi,
On 02/28/2019 10:14 AM, Daniel Axtens wrote:
> Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com> writes:
>
>> In POWER9, OCC(On-Chip-Controller) provides for hard and soft system
>> powercapping range. The hard powercap range is guaranteed while soft
>> powercap may or may not be asserted due to various power-thermal
>> reasons based on system configuration and workloads. This patch adds
>> a sysfs file to export the hard minimum powercap limit to allow the
>> user to set the appropriate powercap value that can be managed by the
>> system.
>
> Maybe it's common terminology and I'm just not aware of it, but what do
> you mean by "asserted"? It doesn't appear elsewhere in the documentation
> you're patching, and it's not a use of assert that I'm familiar with...
>
> Regards,
> Daniel
>
I meant to say powercap will not be assured in the soft powercap range, i.e,
system may or may not be throttled of CPU frequency to remain within the powercap.
I can reword the document and commit message.
Thanks and Regards,
Shilpa
>>
>> Signed-off-by: Shilpasri G Bhat <shilpa.bhat@...ux.vnet.ibm.com>
>> ---
>> .../ABI/testing/sysfs-firmware-opal-powercap | 10 ++++
>> arch/powerpc/platforms/powernv/opal-powercap.c | 66 +++++++++-------------
>> 2 files changed, 37 insertions(+), 39 deletions(-)
>>
>> diff --git a/Documentation/ABI/testing/sysfs-firmware-opal-powercap b/Documentation/ABI/testing/sysfs-firmware-opal-powercap
>> index c9b66ec..65db4c1 100644
>> --- a/Documentation/ABI/testing/sysfs-firmware-opal-powercap
>> +++ b/Documentation/ABI/testing/sysfs-firmware-opal-powercap
>> @@ -29,3 +29,13 @@ Description: System powercap directory and attributes applicable for
>> creates a request for setting a new-powercap. The
>> powercap requested must be between powercap-min
>> and powercap-max.
>> +
>> +What: /sys/firmware/opal/powercap/system-powercap/powercap-hard-min
>> +Date: Feb 2019
>> +Contact: Linux for PowerPC mailing list <linuxppc-dev@...abs.org>
>> +Description: Hard minimum powercap
>> +
>> + This file provides the hard minimum powercap limit in
>> + Watts. The powercap value above hard minimum is always
>> + guaranteed to be asserted and the powercap value below
>> + the hard minimum limit may or may not be guaranteed.
>> diff --git a/arch/powerpc/platforms/powernv/opal-powercap.c b/arch/powerpc/platforms/powernv/opal-powercap.c
>> index d90ee4f..38408e7 100644
>> --- a/arch/powerpc/platforms/powernv/opal-powercap.c
>> +++ b/arch/powerpc/platforms/powernv/opal-powercap.c
>> @@ -139,10 +139,24 @@ static void powercap_add_attr(int handle, const char *name,
>> attr->handle = handle;
>> sysfs_attr_init(&attr->attr.attr);
>> attr->attr.attr.name = name;
>> - attr->attr.attr.mode = 0444;
>> +
>> + if (!strncmp(name, "powercap-current", strlen(name))) {
>> + attr->attr.attr.mode = 0664;
>> + attr->attr.store = powercap_store;
>> + } else {
>> + attr->attr.attr.mode = 0444;
>> + }
>> +
>> attr->attr.show = powercap_show;
>> }
>>
>> +static const char * const powercap_strs[] = {
>> + "powercap-max",
>> + "powercap-min",
>> + "powercap-current",
>> + "powercap-hard-min",
>> +};
>> +
>> void __init opal_powercap_init(void)
>> {
>> struct device_node *powercap, *node;
>> @@ -167,60 +181,34 @@ void __init opal_powercap_init(void)
>>
>> i = 0;
>> for_each_child_of_node(powercap, node) {
>> - u32 cur, min, max;
>> - int j = 0;
>> - bool has_cur = false, has_min = false, has_max = false;
>> + u32 id;
>> + int j, count = 0;
>>
>> - if (!of_property_read_u32(node, "powercap-min", &min)) {
>> - j++;
>> - has_min = true;
>> - }
>> -
>> - if (!of_property_read_u32(node, "powercap-max", &max)) {
>> - j++;
>> - has_max = true;
>> - }
>> + for (j = 0; j < ARRAY_SIZE(powercap_strs); j++)
>> + if (!of_property_read_u32(node, powercap_strs[j], &id))
>> + count++;
>>
>> - if (!of_property_read_u32(node, "powercap-current", &cur)) {
>> - j++;
>> - has_cur = true;
>> - }
>> -
>> - pcaps[i].pattrs = kcalloc(j, sizeof(struct powercap_attr),
>> + pcaps[i].pattrs = kcalloc(count, sizeof(struct powercap_attr),
>> GFP_KERNEL);
>> if (!pcaps[i].pattrs)
>> goto out_pcaps_pattrs;
>>
>> - pcaps[i].pg.attrs = kcalloc(j + 1, sizeof(struct attribute *),
>> + pcaps[i].pg.attrs = kcalloc(count + 1,
>> + sizeof(struct attribute *),
>> GFP_KERNEL);
>> if (!pcaps[i].pg.attrs) {
>> kfree(pcaps[i].pattrs);
>> goto out_pcaps_pattrs;
>> }
>>
>> - j = 0;
>> pcaps[i].pg.name = kasprintf(GFP_KERNEL, "%pOFn", node);
>> - if (has_min) {
>> - powercap_add_attr(min, "powercap-min",
>> - &pcaps[i].pattrs[j]);
>> - pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
>> - j++;
>> - }
>> -
>> - if (has_max) {
>> - powercap_add_attr(max, "powercap-max",
>> - &pcaps[i].pattrs[j]);
>> - pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
>> - j++;
>> - }
>> + for (j = 0; j < ARRAY_SIZE(powercap_strs); j++) {
>> + if (of_property_read_u32(node, powercap_strs[j], &id))
>> + continue;
>>
>> - if (has_cur) {
>> - powercap_add_attr(cur, "powercap-current",
>> + powercap_add_attr(id, powercap_strs[j],
>> &pcaps[i].pattrs[j]);
>> - pcaps[i].pattrs[j].attr.attr.mode |= 0220;
>> - pcaps[i].pattrs[j].attr.store = powercap_store;
>> pcaps[i].pg.attrs[j] = &pcaps[i].pattrs[j].attr.attr;
>> - j++;
>> }
>>
>> if (sysfs_create_group(powercap_kobj, &pcaps[i].pg)) {
>> --
>> 1.8.3.1
>
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