linux-kernel - Re: [Resend PATCH] topology: Set capacity_freq

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Message-ID: <8108129e-d7b8-4540-bf53-ed29cd4bbff9@bp.renesas.com>
Date: Tue, 13 Feb 2024 11:06:48 +0000
From: Paul Barker <paul.barker.ct@...renesas.com>
To: gregkh@...uxfoundation.org
Cc: sudeep.holla@....com, rafael@...nel.org, vschneid@...hat.com,
 bristot@...hat.com, mgorman@...e.de, bsegall@...gle.com,
 rostedt@...dmis.org, dietmar.eggemann@....com, juri.lelli@...hat.com,
 peterz@...radead.org, mingo@...hat.com, lukasz.luba@....com,
 ionela.voinescu@....com, linux-kernel@...r.kernel.org,
 Vincent Guittot <vincent.guittot@...aro.org>
Subject: Re: [Resend PATCH] topology: Set capacity_freq_ref in all cases

Hi Greg,

On 23/01/2024 16:23, Paul Barker wrote:
> On 17/01/2024 19:05, Vincent Guittot wrote:
>> If "capacity-dmips-mhz" is not set, raw_capacity is null and we skip the
>> normalization step which includes setting per_cpu capacity_freq_ref.
>> Always register the notifier but skip the capacity normalization if
>> raw_capacity is null.
>>
>> Fixes: 9942cb22ea45 ("sched/topology: Add a new arch_scale_freq_ref() method")
>> Signed-off-by: Vincent Guittot <vincent.guittot@...aro.org>
> 
> We've had some Ethernet performance issues with linux-next and v6.8-rc1
> on the Renesas RZ/G2L and RZ/G2UL arm64 SoCs. I've confirmed that the
> CPU frequency is stuck at the minimum (150MHz) in v6.8-rc1, even when
> running iperf3. Applying this patch allows the SoC to switch up the the
> maximum frequency (1200MHz) when needed and fixes our Ethernet
> performance.
> 
> iperf3 results in Mbps for RZ/G2L SMARC evaluation board:
>                 TCP TX    TCP RX    UDP TX    UDP RX
> v6.8-rc1        255       175       102       (*)
> +this patch     874       650       802       948
> 
> (*) Testing UDP RX in v6.8-rc1 with a server sending traffic at 1Gbps
> locks up our NFS rootfs mount so we don't get any result at all.
> 
> Results with v6.8-rc1 + this patch are in line with what we see in v6.7.
> 
> Tested-by: Paul Barker <paul.barker.ct@...renesas.com>

I see this patch landed in the 'driver-core-linus' branch of
https://git.kernel.org/pub/scm/linux/kernel/git/gregkh/driver-core.git
on 2024-01-30 as commit 98323e9d7017, however it looks like that hasn't
been merged to Linus' tree yet. In v6.8-rc4 I see the same issue on the
RZ/G2L with the CPU frequency stuck at 150MHz.

Is there anything I need to do to help get this patch merged before v6.8
is released?

Thanks,
Paul
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