linux-kernel - Re: [PATCH v1 00/12] netoops support

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Message-ID: <20101104061544.GD5210@cr0.nay.redhat.com>
Date:	Thu, 4 Nov 2010 14:15:44 +0800
From:	Américo Wang <xiyou.wangcong@...il.com>
To:	Matt Mackall <mpm@...enic.com>
Cc:	Mike Waychison <mikew@...gle.com>, Greg KH <greg@...ah.com>,
	simon.kagstrom@...insight.net, davem@...emloft.net,
	adurbin@...gle.com, akpm@...ux-foundation.org, chavey@...gle.com,
	linux-kernel@...r.kernel.org, linux-api@...r.kernel.org
Subject: Re: [PATCH v1 00/12] netoops support

On Wed, Nov 03, 2010 at 03:54:45PM -0500, Matt Mackall wrote:
>On Wed, 2010-11-03 at 13:29 -0700, Mike Waychison wrote:
>> Mike Waychison wrote:
>> > FWIW, another semantic difference between netconsole and netoops (that
>> > I had missed in the last email) is filtering: we really do want to get
>> > the whole log when a crash happens, debug messages and all.
>> > Netconsole is subject to console filtering (which we _do_ want as
>> > debug messages going out the uart slows the whole world down).
>> > 
>> > netconsole and netoops _do_ have bits in common, for instance the
>> > handling of NETDEV events and source+target configuration.  I'd rather
>> > those bits become common between the two than figure out how to jam
>> > the semantics we need into netconsole.
>> 
>> Hi Matt,
>> 
>> I've been reading through the netconsole driver in response to Greg's 
>> comments on this thread, and it is definitely more robust in terms of 
>> configuration and handling of network device events than the netoops 
>> driver I proposed.
>
>I've been following the discussion to see if it went anywhere
>interesting..
>
>> What are your thoughts on extending netconsole with the same sort of 
>> semantics that are in the netoops patchset?
>
>My first thought is that it's a bit unfortunate that some of the the
>netconsole configgy bits weren't implemented in a generic way that would
>be applicable to other netpoll clients. Some people have never gotten it
>into their heads that netconsole isn't the only client.
>

Really? What are other clients? I remember netdump *was* one client,
but it is not in upstream and is deprecated, so netconsole is the only
client in tree, AFAIK.


>> I'd still like to have blit-dmesg-to-the-network-on-oops semantics, 
>> which seems doable by having a per-target flag for streaming of console 
>> messages (enabled by default) and a flag to emit a structured full dmesg 
>> dump (disabled by default).
>
>I'd actually like to see you go forward with netoops. It's clear to me
>that it's a different beast and complexifying netconsole with a bunch of
>weird new options doesn't really sit well. If that means abstracting
>some of the sysfs crap from netconsole, great. 
>

That would be good.


>That said, I don't think netoops is an ideal name, given how closely
>bound oops _events_ are with their textual output. Presumably it covers
>events other than oopsen like panics too. 
>
>Regarding rolling oopses: lots of machines regularly survive oopses, so 
>I think you ought to consider rate-limiting them (to a configurable rate
>with a very low default) rather than suppressing all but the first.
>

We have WARN_ONCE(), maybe we can make one oops_once()...
At least, that is not hard.
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