Messages in this thread | | | Date | Wed, 2 Apr 2008 23:39:11 +0300 (EEST) | From | "Ilpo Järvinen" <> | Subject | Re: 2.6.25-rc6-git2: warn_on_slowpath for tcp_simple_retransmit |
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On Wed, 2 Apr 2008, Alessandro Suardi wrote:
> On Wed, Apr 2, 2008 at 10:10 AM, Ilpo Järvinen > <ilpo.jarvinen@helsinki.fi> wrote: > > On Wed, 2 Apr 2008, Alessandro Suardi wrote: > > > > > Found this in my FC6-based bittorrent box (K7-800 running > > > a 2.6.25-rc6-git2 kernel) this evening. > > > > > > The kernel was upgraded two weeks ago to fix the bug > > > in which an USB VIA driver hammered the PCI bus > > > causing ATA disk performance to drop, and has been > > > running since then (it still is). > > > > > > So it's actually 2.6.25-rc6-git2 plus patch as in here > > > http://www.gossamer-threads.com/lists/linux/kernel/895506#895506 > > > > > > If there's anything useful I can do, just ask. Thanks ! > > > > Can you reproduce? > > Nope. That only happened once in this uptime: > > [root@donkey ~]# uptime > 21:57:21 up 14 days, 22:04, 5 users, load average: 0.64, 0.47, 0.44 > > The machine runs unattended as a bittorrent client, 24x7, > with a very low traffic (uploading at a steady ~36KB/s, > and downloads happen in peaks). > > I VNC into it in the evening and manage the torrents; > that is all. > > Now, there's an interesting tidbit: > > [root@donkey ~]# ip -s link show eth0 > 3: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast qlen 1000 > link/ether 00:c0:49:a7:33:fe brd ff:ff:ff:ff:ff:ff > RX: bytes packets errors dropped overrun mcast > 959044156 60549131 0 0 0 0 > TX: bytes packets errors dropped carrier collsns > 744533957 66149681 0 0 0 0 > > [root@donkey ~]# ifconfig eth0 > eth0 Link encap:Ethernet HWaddr 00:C0:49:A7:33:FE > inet addr:192.168.1.7 Bcast:192.168.1.255 Mask:255.255.255.0 > inet6 addr: fe80::2c0:49ff:fea7:33fe/64 Scope:Link > UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 > RX packets:60551468 errors:0 dropped:0 overruns:0 frame:0 > TX packets:66152721 errors:0 dropped:0 overruns:1 carrier:0 > collisions:0 txqueuelen:1000 > RX bytes:959199592 (914.7 MiB) TX bytes:748395356 (713.7 MiB) > Interrupt:12 Base address:0xce00 > > Somehow the "overruns" counter is seen differently by 'ip' > and 'ifconfig' - one says 0, the other says 1 - perhaps the > packet that WARN'd me on tcp_simple_retransmit ?
...I find that extreme unlikely.
> If there's anything else - reproducing seems really really > unlikely - 1 packet in 66 million...
Yeah, it seems some hard to hit corner case and so far nobody has a reproducable scenario (or at least I'm not aware of any). I tried to reproduce it last weekend and failed, even with some netem stimuli added while torrenting.
I'll probably ask soon Andrew to queue some low cost debug patch into -mm to get a bit more clues when somebody running mm happens to hit it.
-- i. | |