netdev - Re: [RFC Patch net-next 3/3] net: phy: lan87xx: added ethtool SQI support

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: <YjjFtUEDm2Dta1ez@lunn.ch>
Date:   Mon, 21 Mar 2022 19:36:37 +0100
From:   Andrew Lunn <andrew@...n.ch>
To:     Arun Ramadoss <arun.ramadoss@...rochip.com>
Cc:     linux-kernel@...r.kernel.org, netdev@...r.kernel.org,
        Paolo Abeni <pabeni@...hat.com>,
        Jakub Kicinski <kuba@...nel.org>,
        "David S. Miller" <davem@...emloft.net>,
        Russell King <linux@...linux.org.uk>,
        Heiner Kallweit <hkallweit1@...il.com>,
        UNGLinuxDriver@...rochip.com
Subject: Re: [RFC Patch net-next 3/3] net: phy: lan87xx: added ethtool SQI
 support

> +#define T1_DCQ_SQI_MSK			GENMASK(3, 1)

> +static int lan87xx_get_sqi(struct phy_device *phydev)
> +{
> +	u16 sqi_value[LAN87XX_SQI_ENTRY];

> +	for (i = 0; i < LAN87XX_SQI_ENTRY; i++) {
> +
> +		sqi_value[i] = FIELD_GET(T1_DCQ_SQI_MSK, rc);

> +
> +	/* Sorting SQI values */
> +	sort(sqi_value, LAN87XX_SQI_ENTRY, sizeof(u16), lan87xx_sqi_cmp, NULL);

Sort is quite heavyweight. Your SQI values are in the range 0-7 right?
So rather than have an array of LAN87XX_SQI_ENTRY entries, why not
create a histogram? You then just need to keep 8 uints. There is no
need to perform a sort to discard the outliers, simply remove from the
outer histogram buckets. And then you can calculate the average.

That should be faster and use less memory.

     Andrew