linux-kernel - Re: [PATCH v4 19/24] PM / devfreq: tegra30: Optimize upper consecutive watermark selection

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <17fabbaf-ceca-7551-0a58-9c8a0e7027ed@samsung.com>
Date:   Thu, 18 Jul 2019 18:51:02 +0900
From:   Chanwoo Choi <cw00.choi@...sung.com>
To:     Dmitry Osipenko <digetx@...il.com>,
        Thierry Reding <thierry.reding@...il.com>,
        MyungJoo Ham <myungjoo.ham@...sung.com>,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Jonathan Hunter <jonathanh@...dia.com>,
        Tomeu Vizoso <tomeu.vizoso@...labora.com>
Cc:     linux-pm@...r.kernel.org, linux-tegra@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 19/24] PM / devfreq: tegra30: Optimize upper
 consecutive watermark selection

On 19. 7. 8. 오전 7:32, Dmitry Osipenko wrote:
> The memory activity counter may get a bit higher than a watermark which
> is selected based on OPP that corresponds to a highest EMC rate, in this
> case watermark is lower than the actual memory activity is and thus
> results in unwanted "upper" interrupts.
> 
> Signed-off-by: Dmitry Osipenko <digetx@...il.com>
> ---
>  drivers/devfreq/tegra30-devfreq.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)

It seems that you can combine patch19 with patch20.

> 
> diff --git a/drivers/devfreq/tegra30-devfreq.c b/drivers/devfreq/tegra30-devfreq.c
> index 8d6bf6e9f1ae..c3cf87231d25 100644
> --- a/drivers/devfreq/tegra30-devfreq.c
> +++ b/drivers/devfreq/tegra30-devfreq.c
> @@ -363,7 +363,18 @@ static void tegra_devfreq_update_wmark(struct tegra_devfreq *tegra,
>  	tegra_actmon_get_lower_upper(tegra, dev, freq - 1, &lower, &upper);
>  
>  	delta = do_percent(upper - lower, dev->config->boost_up_threshold);
> -	device_writel(dev, lower + delta, ACTMON_DEV_UPPER_WMARK);
> +
> +	/*
> +	 * The memory events count could go a bit higher than the maximum
> +	 * defined by the OPPs, hence make the upper watermark infinitely
> +	 * high to avoid unnecessary upper interrupts in that case.
> +	 */
> +	if (freq == tegra->max_freq)
> +		upper = ULONG_MAX;
> +	else
> +		upper = lower + delta;
> +
> +	device_writel(dev, upper, ACTMON_DEV_UPPER_WMARK);
>  
>  	/*
>  	 * Meanwhile the lower mark is based on the average value
> 


-- 
Best Regards,
Chanwoo Choi
Samsung Electronics