netdev - Re: KS8695: possible NAPI issue

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Date:	Thu, 4 Mar 2010 11:10:37 +0100
From:	Yegor Yefremov <yegorslists@...glemail.com>
To:	figo zhang <figo1802@...il.com>
Cc:	Dick Hollenbeck <dick@...tplc.com>, netdev@...r.kernel.org,
	zealcook@...il.com
Subject: Re: KS8695: possible NAPI issue

>>> I'm using 2.6.33 kernel and I noticed such a strange behavior:
>>>
>>> after system start I transfer one file via netcat from my development
>>> host, after this transfer the network is not functioning i.e. no pings
>>> possible etc.
>>>
>>> To narrow down the problem I checked out this commit
>>>
>>> http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commit;h=451f14439847db302e5104c44458b2dbb4b1829d.
>>> Till here the network driver is functioning as intended, but after
>>> NAPI introduction I have this issue. With latest git-pull of "Linus'
>>> kernel tree" I can't even ping right after the systems start.
>>>
>>> Any Ideas? What am I missing?
>>>
>>
>> No idea, although I am using the same ARM chip, my kernel is at 2.6.30.5,
>> and except for this occasional loss of connection I get, the ethernet driver
>> seems to work better than what you are reporting.
>
> from linux-2.6.32, this ethernet  driver have add NAPI support, would
> you like to
> try using this version?

Figo, I just looked at the 2.6.32 kernel and found out that it
doesn't' contain NAPI support (see the history
http://git.kernel.org/?p=linux/kernel/git/stable/linux-2.6.32.y.git;a=history;f=drivers/net/arm/ks8695net.c;h=2a7b7745cc55b54cefada690b0ea47865b54b6b9;hb=HEAD).
So 2.6.33 is the first stable kernel to support NAPI.

I made some further tests but I can't find the reason for network
failures: the interrupts are coming and the packets will be received
and sent so that rx/tx counters would be increased, but none of them
seem to reach the IP stack. I don't know where and why the things get
desynchronized.

Could you try the 2.6.33 or Linus tree? Thank you in advance.

Regards,
Yegor
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