linux-kernel - Re: [PATCH v3 6/9] cpu/SMT: Allow enabling partial SMT states via sysfs

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Message-ID: <5801fb9a94c2ce00ca44220be0b1a5bd7f8ff44f.camel@intel.com>
Date:   Wed, 5 Jul 2023 03:14:55 +0000
From:   "Zhang, Rui" <rui.zhang@...el.com>
To:     "linuxppc-dev@...ts.ozlabs.org" <linuxppc-dev@...ts.ozlabs.org>,
        "ldufour@...ux.ibm.com" <ldufour@...ux.ibm.com>
CC:     lkp <lkp@...el.com>, "npiggin@...il.com" <npiggin@...il.com>,
        "dave.hansen@...ux.intel.com" <dave.hansen@...ux.intel.com>,
        "bp@...en8.de" <bp@...en8.de>,
        "mingo@...hat.com" <mingo@...hat.com>,
        "tglx@...utronix.de" <tglx@...utronix.de>,
        "christophe.leroy@...roup.eu" <christophe.leroy@...roup.eu>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "mpe@...erman.id.au" <mpe@...erman.id.au>,
        "linux-arch@...r.kernel.org" <linux-arch@...r.kernel.org>
Subject: Re: [PATCH v3 6/9] cpu/SMT: Allow enabling partial SMT states via
 sysfs

On Thu, 2023-06-29 at 16:31 +0200, Laurent Dufour wrote:
> @@ -2580,6 +2597,17 @@ static ssize_t control_show(struct device
> *dev,
>  {
>         const char *state = smt_states[cpu_smt_control];
>  
> +#ifdef CONFIG_HOTPLUG_SMT
> +       /*
> +        * If SMT is enabled but not all threads are enabled then
> show the
> +        * number of threads. If all threads are enabled show "on".
> Otherwise
> +        * show the state name.
> +        */
> +       if (cpu_smt_control == CPU_SMT_ENABLED &&
> +           cpu_smt_num_threads != cpu_smt_max_threads)
> +               return sysfs_emit(buf, "%d\n", cpu_smt_num_threads);
> +#endif
> +

My understanding is that cpu_smt_control is always set to
CPU_SMT_NOT_IMPLEMENTED when CONFIG_HOTPLUG_SMT is not set, so this
ifdef is not necessary, right?

thanks,
rui