lkml.org 
[lkml]   [2020]   [Apr]   [16]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
SubjectRe: [PATCH 2/4] x86, sched: Account for CPUs with less than 4 cores in freq. invariance
From
Date
On 4/16/20 12:47 AM, Giovanni Gherdovich wrote:
> If a CPU has less than 4 physical cores, MSR_TURBO_RATIO_LIMIT will
> rightfully report that the 4C turbo ratio is zero. In such cases, use the
> 1C turbo ratio instead for frequency invariance calculations.

Thank you! This makes my Lenovo T410 happy again. I had tracked down the
problem and come up with a similar patch. I was about to report it when
I came across this patch set.

>
> Reported-by: Neil Rickert <nwr10cst-oslnx@yahoo.com>
> Reported-by: Like Xu <like.xu@linux.intel.com>
> Signed-off-by: Giovanni Gherdovich <ggherdovich@suse.cz>
> Fixes: 1567c3e3467c ("x86, sched: Add support for frequency invariance")

Tested-by: Dave Kleikamp <dave.kleikamp@oracle.com>

> ---
> arch/x86/kernel/smpboot.c | 11 ++++++++---
> 1 file changed, 8 insertions(+), 3 deletions(-)
>
> diff --git a/arch/x86/kernel/smpboot.c b/arch/x86/kernel/smpboot.c
> index 3a318ec9bc17..5d346b70844b 100644
> --- a/arch/x86/kernel/smpboot.c
> +++ b/arch/x86/kernel/smpboot.c
> @@ -1945,18 +1945,23 @@ static bool skx_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq, int size)
>
> static bool core_set_max_freq_ratio(u64 *base_freq, u64 *turbo_freq)
> {
> + u64 msr;
> int err;
>
> err = rdmsrl_safe(MSR_PLATFORM_INFO, base_freq);
> if (err)
> return false;
>
> - err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, turbo_freq);
> + err = rdmsrl_safe(MSR_TURBO_RATIO_LIMIT, &msr);
> if (err)
> return false;
>
> - *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
> - *turbo_freq = (*turbo_freq >> 24) & 0xFF; /* 4C turbo */
> + *base_freq = (*base_freq >> 8) & 0xFF; /* max P state */
> + *turbo_freq = (msr >> 24) & 0xFF; /* 4C turbo */
> +
> + /* The CPU may have less than 4 cores */
> + if (!*turbo_freq)
> + *turbo_freq = msr & 0xFF; /* 1C turbo */
>
> return true;
> }
>

\
 
 \ /
  Last update: 2020-04-16 17:30    [W:0.270 / U:2.112 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site