Re: AMD Pstate

[Huang Rui <ray.huang@amd.com>]

On Tue, Nov 23, 2021 at 06:47:34PM +0800, Mike Lothian wrote:
> Hi again
> 
> Do I need to enable something else for shedutil to work, I've tried
> with and without shared_mem? Compiling a kernel with -j16 has the freq
> stuck at 1GHz on all cores - ondemand works fine
> 

If you set the CONFIG_CPU_FREQ_GOV_SCHEDUTIL, then no more configurations.

Did you use the V4 version?

https://git.kernel.org/pub/scm/linux/kernel/git/rui/linux.git/log/?h=amd-pstate-dev-v4

> That's on a AMD Ryzen 9 5900HX
> 
> Also compiling with Clang-13 gives the following warnings:
> 
> drivers/cpufreq/amd-pstate.c:257:6: warning: variable 'amd_des_perf'
> is used uninitialized whenever 'if' condition is false
> [-Wsometimes-uninitialized]
> 
>         if (target_perf < capacity)
> 
>             ^~~~~~~~~~~~~~~~~~~~~~
> 
> drivers/cpufreq/amd-pstate.c:272:40: note: uninitialized use occurs here
> 
>         amd_des_perf = clamp_t(unsigned long, amd_des_perf,
> 
>                                               ^~~~~~~~~~~~

Ah, miss one line. Thanks for the info. I will correct it.

Thanks,
Ray

> 
> ./include/linux/minmax.h:124:60: note: expanded from macro 'clamp_t'
> 
> #define clamp_t(type, val, lo, hi) min_t(type, max_t(type, val, lo), hi)
> 
>                                                            ^~~
> 
> ./include/linux/minmax.h:112:48: note: expanded from macro 'max_t'
> 
> #define max_t(type, x, y)       __careful_cmp((type)(x), (type)(y), >)
> 
>                                                      ^
> 
> ./include/linux/minmax.h:38:14: note: expanded from macro '__careful_cmp'
> 
>                 __cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
> 
>                            ^
> 
> note: (skipping 1 expansions in backtrace; use
> -fmacro-backtrace-limit=0 to see all)
> 
> ./include/linux/minmax.h:104:48: note: expanded from macro 'min_t'
> 
> #define min_t(type, x, y)       __careful_cmp((type)(x), (type)(y), <)
> 
>                                                      ^
> 
> ./include/linux/minmax.h:38:14: note: expanded from macro '__careful_cmp'
> 
>                 __cmp_once(x, y, __UNIQUE_ID(__x), __UNIQUE_ID(__y), op))
> 
>                            ^
> 
> ./include/linux/minmax.h:31:25: note: expanded from macro '__cmp_once'
> 
>                 typeof(x) unique_x = (x);               \
> 
>                                       ^
> 
> drivers/cpufreq/amd-pstate.c:257:2: note: remove the 'if' if its
> condition is always true
> 
>         if (target_perf < capacity)
> 
>         ^~~~~~~~~~~~~~~~~~~~~~~~~~~
> 
> drivers/cpufreq/amd-pstate.c:249:56: note: initialize the variable
> 'amd_des_perf' to silence this warning
> 
>         unsigned long amd_max_perf, amd_min_perf, amd_des_perf,
> 
>                                                               ^
> 
>                                                                = 0
> 
> On Sun, 21 Nov 2021 at 10:37, Mike Lothian <mike@fireburn.co.uk> wrote:
> >
> > Hi
> >
> > I'm not subscribed to the mailing list so apologies for emailing you directly
> >
> > It looks like something isn't quite right with the kconfig selects
> >
> > SCHED_MC_PRIO can't be enabled without CPU_SUP_INTEL
> >
> >
> >
> > │ Symbol: X86_AMD_PSTATE [=y]
> >
> >                                                               │
> >  │ Type  : bool
> >
> >                                                                │
> >  │ Defined at drivers/cpufreq/Kconfig.x86:37
> >
> >                                                                │
> >  │   Prompt: AMD Processor P-State driver
> >
> >                                                                │
> >  │   Depends on: CPU_FREQ [=y] && X86 [=y]
> >
> >                                                                │
> >  │   Location:
> >
> >                                                                │
> >  │     Main menu
> >
> >                                                                │
> >  │       -> Power management and ACPI options
> >
> >                                                                │
> >  │         -> CPU Frequency scaling
> >
> >                                                                │
> >  │           -> CPU Frequency scaling (CPU_FREQ [=y])
> >
> >                                                                │
> >  │ Selects: ACPI_PROCESSOR [=y] && ACPI_CPPC_LIB [=n] &&
> > CPU_FREQ_GOV_SCHEDUTIL [=y]
> >
> >
> >
> > │ Symbol: ACPI_CPPC_LIB [=n]
> >
> >                                                               │
> >  │ Type  : bool
> >
> >                                                                │
> >  │ Defined at drivers/acpi/Kconfig:268
> >
> >                                                                │
> >  │   Depends on: ACPI [=y] && ACPI_PROCESSOR [=y]
> >
> >                                                                │
> >  │ Selects: MAILBOX [=n] && PCC [=n]
> >
> >                                                                │
> >  │ Selected by [n]:
> >
> >                                                                │
> >  │   - X86_INTEL_PSTATE [=n] && CPU_FREQ [=y] && X86 [=y] && X86_64
> > [=y] && ACPI [=y] && SCHED_MC_PRIO [=n]
> >                                                                   │
> >  │   - X86_AMD_PSTATE [=y] && CPU_FREQ [=y] && X86 [=y] && X86_64 [=y]
> > && ACPI [=y] && SCHED_MC_PRIO [=n]
> >                                                                │
> >  │   - ACPI_CPPC_CPUFREQ [=n] && CPU_FREQ [=y] && (ARM || ARM64) &&
> > ACPI_PROCESSOR [=y]
> >
> >
> >
> > │ Symbol: SCHED_MC_PRIO [=n]
> >
> >                                                               │
> >  │ Type  : bool
> >
> >                                                                │
> >  │ Defined at arch/x86/Kconfig:1029
> >
> >                                                                │
> >  │   Prompt: CPU core priorities scheduler support
> >
> >                                                                │
> >  │   Depends on: SCHED_MC [=y] && CPU_SUP_INTEL [=n]
> >
> >                                                                │
> >  │   Location:
> >
> >                                                                │
> >  │     Main menu
> >
> >                                                                │
> >  │       -> Processor type and features
> >
> >                                                                │
> >  │ (1)     -> Multi-core scheduler support (SCHED_MC [=y])
> >
> >                                                                │
> >  │ Selects: X86_INTEL_PSTATE [=n] && CPU_FREQ [=y]
> >
> >
> >
> > I've used this patch to work around the issue:
> >
> > diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> > index 95dd1ee01546..bdfcf155f48e 100644
> > --- a/arch/x86/Kconfig
> > +++ b/arch/x86/Kconfig
> > @@ -1028,8 +1028,8 @@ config SCHED_MC
> >
> > config SCHED_MC_PRIO
> >        bool "CPU core priorities scheduler support"
> > -       depends on SCHED_MC && CPU_SUP_INTEL
> > -       select X86_INTEL_PSTATE
> > +       depends on SCHED_MC && CPU_SUP_AMD
> > +       select X86_AMD_PSTATE
> >        select CPU_FREQ
> >        default y
> >        help
> >
> > Which gets things working here