Re: [PATCH 6/9] cpu/SMT: Allow enabling partial SMT states via sysfs

Thomas Gleixner
2023-06-10T20:13:24Z

On Sat, Jun 10 2023 at 22:09, Thomas Gleixner wrote:

> On Thu, May 25 2023 at 01:56, Michael Ellerman wrote:
>> There is a hook which allows arch code to control how many threads per
>
> Can you please write out architecture in changelogs and comments?
>
> I know 'arch' is commonly used but while my brain parser tolerates
> 'arch_' prefixes it raises an exception on 'arch' in prose as 'arch' is
> a regular word with a completely different meaning. Changelogs and
> comments are not space constraint.
>
>> @@ -2505,20 +2505,38 @@ __store_smt_control(struct device *dev, struct device_attribute *attr,
>> if (cpu_smt_control == CPU_SMT_NOT_SUPPORTED)
>> return -ENODEV;
>>
>> - if (sysfs_streq(buf, "on"))
>> + if (sysfs_streq(buf, "on")) {
>> ctrlval = CPU_SMT_ENABLED;
>> - else if (sysfs_streq(buf, "off"))
>> + num_threads = cpu_smt_max_threads;
>> + } else if (sysfs_streq(buf, "off")) {
>> ctrlval = CPU_SMT_DISABLED;
>> - else if (sysfs_streq(buf, "forceoff"))
>> + num_threads = 1;
>> + } else if (sysfs_streq(buf, "forceoff")) {
>> ctrlval = CPU_SMT_FORCE_DISABLED;
>> - else
>> + num_threads = 1;
>> + } else if (kstrtoint(buf, 10, &num_threads) == 0) {
>> + if (num_threads == 1)
>> + ctrlval = CPU_SMT_DISABLED;
>> + else if (num_threads > 1 && topology_smt_threads_supported(num_threads))

Why does this not simply check cpu_smt_max_threads?

else if (num_threads > 1 && num_threads <= cpu_smt_max_threads)

cpu_smt_max_threads should have been established already, no?

Thanks,

tglx