netdev - Re: [PATCH net] net: stmmac: Use hrtimer for TX coalescing

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: <20201123164600.434b6a9e@kicinski-fedora-pc1c0hjn.dhcp.thefacebook.com>
Date:   Mon, 23 Nov 2020 16:46:00 -0800
From:   Jakub Kicinski <kuba@...nel.org>
To:     Vincent Whitchurch <vincent.whitchurch@...s.com>
Cc:     <peppe.cavallaro@...com>, <alexandre.torgue@...com>,
        <joabreu@...opsys.com>, <davem@...emloft.net>, <kernel@...s.com>,
        <netdev@...r.kernel.org>
Subject: Re: [PATCH net] net: stmmac: Use hrtimer for TX coalescing

On Fri, 20 Nov 2020 16:02:08 +0100 Vincent Whitchurch wrote:
> This driver uses a normal timer for TX coalescing, which means that the
> with the default tx-usecs of 1000 microseconds the cleanups actually
> happen 10 ms or more later with HZ=100.  This leads to very low
> througput with TCP when bridged to a slow link such as a 4G modem.  Fix
> this by using an hrtimer instead.
> 
> On my ARM platform with HZ=100 and the default TX coalescing settings
> (tx-frames 25 tx-usecs 1000), with "tc qdisc add dev eth0 root netem
> delay 60ms 40ms rate 50Mbit" run on the server, netperf's TCP_STREAM
> improves from ~5.5 Mbps to ~100 Mbps.
> 
> Signed-off-by: Vincent Whitchurch <vincent.whitchurch@...s.com>

Looks perfectly reasonable, but you marked it for net. Do you consider
this to be a bug fix, and need it backported to stable? Otherwise I'd
rather apply it to net-next.