linux-kernel - Re: [PATCH net-next 05/14] net: ethernet: mtk_eth

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 for Android: free password hash cracker in your pocket

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

Message-ID: <d96206db-96e2-1eb7-6b19-47c9596ccfea@nbd.name>
Date:   Thu, 22 Apr 2021 14:33:31 +0200
From:   Felix Fietkau <nbd@....name>
To:     Ilya Lipnitskiy <ilya.lipnitskiy@...il.com>,
        John Crispin <john@...ozen.org>,
        Sean Wang <sean.wang@...iatek.com>,
        Mark Lee <Mark-MC.Lee@...iatek.com>,
        "David S. Miller" <davem@...emloft.net>,
        Jakub Kicinski <kuba@...nel.org>,
        Matthias Brugger <matthias.bgg@...il.com>,
        netdev@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-arm-kernel@...ts.infradead.org,
        linux-mediatek@...ts.infradead.org
Subject: Re: [PATCH net-next 05/14] net: ethernet: mtk_eth_soc: reduce MDIO
 bus access latency


On 2021-04-22 06:09, Ilya Lipnitskiy wrote:
> From: Felix Fietkau <nbd@....name>
> 
> usleep_range often ends up sleeping much longer than the 10-20us provided
> as a range here. This causes significant latency in mdio bus acceses,
> which easily adds multiple seconds to the boot time on MT7621 when polling
> DSA slave ports.
> 
> Use udelay via readx_poll_timeout_atomic, since the MDIO access does not
> take much time
> 
> Signed-off-by: Felix Fietkau <nbd@....name>
> [Ilya: use readx_poll_timeout_atomic instead of cond_resched]
I still prefer the cond_resched() variant. On a fully loaded system, I'd
prefer to let the MDIO access take longer instead of wasting cycles on
udelay.

- Felix