linux-kernel - Re: [PATCH] intel_idle: Add Jasper Lake and Elkhart Lake support

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Message-ID: <2048df524f8be7ed200bc92eb1c6efe106f0ed19.camel@intel.com>
Date: Fri, 26 Jul 2024 06:51:54 +0000
From: "Zhang, Rui" <rui.zhang@...el.com>
To: "kai.heng.feng@...onical.com" <kai.heng.feng@...onical.com>,
	"jacob.jun.pan@...ux.intel.com" <jacob.jun.pan@...ux.intel.com>,
	"lenb@...nel.org" <lenb@...nel.org>
CC: "linux-pm@...r.kernel.org" <linux-pm@...r.kernel.org>,
	"artem.bityutskiy@...ux.intel.com" <artem.bityutskiy@...ux.intel.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH] intel_idle: Add Jasper Lake and Elkhart Lake support

On Fri, 2024-07-26 at 14:26 +0800, Kai-Heng Feng wrote:
> Without proper C-state support, the CPU can take long time to exit to
> C0
> to handle IRQ and perform DMA.

Can you provide more details?

Say, what cstate is entered w/ and w/o this patch?

can you show the output of "grep .
/sys/devices/system/cpu/cpu0/cpuidle/state*/*" without this patch?

> 
> The data collect via wult shows the latency is similar to Broxton, so
> use the existing table to support C-state on JSL and EHL.

so you have done cstate measurement on the EHL using wult?
can you share more details about the measurement results?

thanks,
rui

> 
> Link: https://bugzilla.kernel.org/show_bug.cgi?id=219023
> Signed-off-by: Kai-Heng Feng <kai.heng.feng@...onical.com>
> ---
>  drivers/idle/intel_idle.c | 2 ++
>  1 file changed, 2 insertions(+)
> 
> diff --git a/drivers/idle/intel_idle.c b/drivers/idle/intel_idle.c
> index 9aab7abc2ae9..eb6975a1d083 100644
> --- a/drivers/idle/intel_idle.c
> +++ b/drivers/idle/intel_idle.c
> @@ -1538,6 +1538,8 @@ static const struct x86_cpu_id intel_idle_ids[]
> __initconst = {
>         X86_MATCH_VFM(INTEL_ATOM_GOLDMONT,      &idle_cpu_bxt),
>         X86_MATCH_VFM(INTEL_ATOM_GOLDMONT_PLUS, &idle_cpu_bxt),
>         X86_MATCH_VFM(INTEL_ATOM_GOLDMONT_D,    &idle_cpu_dnv),
> +       X86_MATCH_VFM(INTEL_ATOM_TREMONT,       &idle_cpu_bxt),
> +       X86_MATCH_VFM(INTEL_ATOM_TREMONT_L,     &idle_cpu_bxt),
>         X86_MATCH_VFM(INTEL_ATOM_TREMONT_D,     &idle_cpu_snr),
>         X86_MATCH_VFM(INTEL_ATOM_CRESTMONT,     &idle_cpu_grr),
>         X86_MATCH_VFM(INTEL_ATOM_CRESTMONT_X,   &idle_cpu_srf),