netdev - Re: via-rhine interrupts

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]

Date:	Wed, 18 Aug 2010 23:49:39 -0700 (PDT)
From:	David Miller <davem@...emloft.net>
To:	jarkao2@...il.com
Cc:	ruzicka.jakub@...il.com, netdev@...r.kernel.org
Subject: Re: via-rhine interrupts

From: Jarek Poplawski <jarkao2@...il.com>
Date: Sun, 15 Aug 2010 22:04:31 +0200

> I've just tested it using a simplistic patch below, which skips
> some napi receiving by doing it only every second jiffie (on even
> ones), and I've got around 30% less interrupts from via-rhine,
> which seems to suggest napi works OK, but there is too low
> traffic (or too fast soft interrupt handling) to affect hard
> interrupts. (Btw, probably CONFIG_HZ can matter here a bit too.
> I tested with 1000.)

100Mbit on any modern system isn't going to trigger NAPI much at all
even with near full link utilization.

The simply cpu processes the packets too fast for them to gather up
much at all.

Some improvement in polling could be gained if the via-rhine has some
HW interrupt mitigation settings.  However after a quick perusal of
the driver I don't see anything about this.  The mitigation ethtool
ops aren't implemented either, so I'm not optimistic :-)

--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html