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Old 05-02-2011, 06:39 PM   #1
rbonafied
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Help! Why does my connection to my linux box slow to a crawl?


Hi,

I have a linux server that has seemingly random network slow downs. This server is mainly my dvr. I'm starting to think it's a hardware problem, but that's just a gut feeling. I don't really know how to determine if it isn't.

Slow summary:
  • SSH, HTTP, VNC incoming traffic are all affected
  • Outgoing traffic seems ok. I haven't tested this as much.
  • Rebooting mostly helps.
  • Stopping/starting network doesn't help
  • Load average is below 1.0
  • Updated Kernel with no change

Server Specs:
  • GIGABYTE GA-MA785GM-US2H AM3/AM2+/AM2 AMD 785G HDMI Micro ATX AMD Motherboard
  • Onboard LAN
  • BIOS updated to latest
[LIST]Mandriva Linux 2010.2 - Kernel 2.6.33.7

Captured during one of the slowdown
eth0 Link encap:Ethernet HWaddr 6C:F0:49:00:A7:90
inet addr:192.168.0.193 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:444487 errors:0 dropped:0 overruns:0 frame:0
TX packets:237566 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:643320919 (613.5 MiB) TX bytes:26721696 (25.4 MiB)
Interrupt:27 Base address:0x4000

eth0: negotiated 100baseTx-FD flow-control, link ok
product info: vendor 00:07:32, model 17 rev 2
basic mode: autonegotiation enabled
basic status: autonegotiation complete, link ok
capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control

IC statistics:
tx_packets: 237597
rx_packets: 444507
tx_errors: 0
rx_errors: 0
rx_missed: 0
align_errors: 0
tx_single_collisions: 0
tx_multi_collisions: 0
unicast: 443724
broadcast: 481
multicast: 303
tx_aborted: 0
tx_underrun: 0

 
Old 05-03-2011, 02:05 AM   #2
kbp
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Looks like you have a gigabit nic but the switch is only 100Mb, there are no errors though so it doesn't look like a physical network problem. Try running sar to collect some stats... ?
 
Old 05-03-2011, 07:03 AM   #3
rbonafied
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Hi KBP,

My Mandriva distro doesn't have sar. Is there another utility I can use? Does plugging a gigabit card into a 100mb router typically cause this type of behavior?

Thanks!
R
 
Old 05-03-2011, 07:12 AM   #4
stress_junkie
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sar is in the sysstat Linux package.

A gigabit card should autonegotiate its speed with the router when the computer or router is first turned on. To answer your question no there should be no problem with mixing a gigabit NIC with a 100 mb router.

In addition to using sar, which will show the usage of system resources over time, I would run Wireshark during the times that the computer is responding slowly. You can look for problems such as duplicate packets and out of order packets. These kinds of things would indicate a hardware problem. You can also look for other problems using Wireshark such as lots of SYN packets or lots of RST packets. These would indicate a configuration problem with the network clients or other problems coming from the client computer trying to interact with the server.

Last edited by stress_junkie; 05-03-2011 at 07:19 AM.
 
Old 05-03-2011, 06:04 PM   #5
rbonafied
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Thanks!

I installed sysstat and have it set to collect. In my original post, I forget to mention that I ran wireshark during one of the slowdowns and didn't record much, if any, activity. I saved the output file from before and will look at it again after I become more familiar with the utility. Hopefully, I'll have something to report in a few days to a week.
 
Old 05-03-2011, 06:19 PM   #6
markush
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Are your DNS-settings configured properly? you may check "cat /etc/resolv.conf"

Since you have captured the traffic with wireshark, you may as well look for traffic on port 53.

Markus
 
Old 05-31-2011, 08:57 PM   #7
rbonafied
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Well, it's been a few weeks and the problem still exists. I captured a sar -A during one of the outages. Should I post the whole output? It's large.

Symptoms now include dropping entirely off the network from both directions. (No route to host) . When I disconnect the cable and reconnect it, it works again for a short time.

I just noticed this in the log after I unplugged and replugged the cable in:

May 31 21:50:52 notivo kernel: r8169: eth0: link down
May 31 21:50:52 notivo ifplugd(eth0)[2297]: Link beat lost.
May 31 21:50:58 notivo ifplugd(eth0)[2297]: Executing '/etc/ifplugd/ifplugd.action eth0 down'.
May 31 21:50:58 notivo avahi-daemon[2708]: Withdrawing address record for 192.168.0.193 on eth0.
May 31 21:50:58 notivo avahi-daemon[2708]: Leaving mDNS multicast group on interface eth0.IPv4 with address 192.168.0.193.
May 31 21:50:58 notivo avahi-daemon[2708]: Interface eth0.IPv4 no longer relevant for mDNS.
May 31 21:51:00 notivo vnstatd[2603]: SIGHUP received, flushing data to disk and reloading config.
May 31 21:51:00 notivo ifplugd(eth0)[2297]: client: Reloading vnstatd configuration: #033[65G[#033[1;32m OK #033[0;39m]#015
May 31 21:51:00 notivo ifplugd(eth0)[2297]: Program executed successfully.
May 31 21:51:00 notivo kernel: ifplugd: page allocation failure. order:3, mode:0x4020
r8169: eth0: link down
ifplugd: page allocation failure. order:3, mode:0x4020
Pid: 2297, comm: ifplugd Tainted: P 2.6.33.7-desktop-2mnb #1
Call Trace:
[<c04292ab>] ? printk+0x1d/0x22
[<c01c2156>] __alloc_pages_nodemask+0x466/0x5a0
[<c01c22ac>] __get_free_pages+0x1c/0x30
[<c01ed936>] __kmalloc_track_caller+0x106/0x170
[<c038ee43>] ? __netdev_alloc_skb+0x23/0x40
[<c038eb2e>] __alloc_skb+0x4e/0x130
[<c038ee43>] __netdev_alloc_skb+0x23/0x40
[<f7f7e35f>] rtl8169_rx_fill+0x9f/0x1c0 [r8169]
[<f7f7e4e5>] rtl8169_init_ring+0x65/0xa0 [r8169]
[<f7f7f8c7>] rtl8169_open+0xd7/0x3a0 [r8169]
[<c0107990>] ? dma_generic_alloc_coherent+0x0/0xc0
[<c0397e42>] dev_open+0x92/0xf0
[<c042bfa3>] ? _raw_spin_unlock_bh+0x13/0x20
[<c0397aef>] ? dev_set_rx_mode+0x2f/0x40
[<c0397c9b>] dev_change_flags+0x7b/0x190
[<c03e9f43>] devinet_ioctl+0x673/0x6d0
[<c039b73d>] ? dev_ioctl+0x52d/0x6d0
[<c03eb025>] inet_ioctl+0x95/0xb0
[<c0387f6d>] sock_ioctl+0x6d/0x270
[<c01d5f95>] ? do_wp_page+0xb5/0x740
[<c0201852>] vfs_ioctl+0x32/0xb0
[<c0387f00>] ? sock_ioctl+0x0/0x270
[<c0202032>] do_vfs_ioctl+0x72/0x5c0
[<c016a9c7>] ? ktime_get_ts+0xe7/0x110
[<c02a48e9>] ? copy_to_user+0x39/0x130
[<c0202c4a>] ? poll_select_copy_remaining+0xca/0x110
[<c02025e7>] sys_ioctl+0x67/0x80
[<c0103bdf>] sysenter_do_call+0x12/0x28
Mem-Info:
DMA per-cpu:
CPU 0: hi: 0, btch: 1 usd: 0
CPU 1: hi: 0, btch: 1 usd: 0
Normal per-cpu:
CPU 0: hi: 186, btch: 31 usd: 170
CPU 1: hi: 186, btch: 31 usd: 171
HighMem per-cpu:
CPU 0: hi: 186, btch: 31 usd: 160
CPU 1: hi: 186, btch: 31 usd: 171
active_anon:100001 inactive_anon:52866 isolated_anon:0
active_file:125301 inactive_file:179698 isolated_file:0
unevictable:0 dirty:232 writeback:0 unstable:0
free:20033 slab_reclaimable:10651 slab_unreclaimable:3210
mapped:20303 shmem:8164 pagetables:1346 bounce:0
DMA free:3476kB min:64kB low:80kB high:96kB active_anon:0kB inactive_anon:0kB active_file:5060kB inactive_file:392kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:15868kB mlocked:0kB dirty:0kB writeback:0kB mapped:0kB shmem:0kB slab_reclaimable:196kB slab_unreclaimable:16kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 861 2014 2014
Normal free:57920kB min:3720kB low:4648kB high:5580kB active_anon:45536kB inactive_anon:70500kB active_file:219984kB inactive_file:337176kB unevictable:0kB isolated(anon):0kB isolated(file):132kB present:881880kB mlocked:0kB dirty:228kB writeback:0kB mapped:17324kB shmem:4784kB slab_reclaimable:42408kB slab_unreclaimable:12824kB kernel_stack:2808kB pagetables:5384kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:33 all_unreclaimable? no
lowmem_reserve[]: 0 0 9222 9222
HighMem free:18736kB min:512kB low:1756kB high:3000kB active_anon:354468kB inactive_anon:140964kB active_file:276160kB inactive_file:381092kB unevictable:0kB isolated(anon):0kB isolated(file):0kB present:1180536kB mlocked:0kB dirty:700kB writeback:0kB mapped:63888kB shmem:27872kB slab_reclaimable:0kB slab_unreclaimable:0kB kernel_stack:0kB pagetables:0kB unstable:0kB bounce:0kB writeback_tmp:0kB pages_scanned:0 all_unreclaimable? no
lowmem_reserve[]: 0 0 0 0
DMA: 5*4kB 2*8kB 7*16kB 0*32kB 0*64kB 0*128kB 1*256kB 0*512kB 1*1024kB 1*2048kB 0*4096kB = 3476kB
Normal: 13533*4kB 379*8kB 37*16kB 3*32kB 1*64kB 1*128kB 0*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 58044kB
HighMem: 3266*4kB 483*8kB 31*16kB 13*32kB 6*64kB 0*128kB 2*256kB 0*512kB 0*1024kB 0*2048kB 0*4096kB = 18736kB
313513 total pagecache pages
381 pages in swap cache
Swap cache stats: add 23166, delete 22785, find 4723672/4723729
Free swap = 5025984kB
Total swap = 5116660kB
523760 pages RAM
297458 pages HighMem
6189 pages reserved
385492 pages shared
225006 pages non-shared


Here is some output from a few other commands:

eth0 Link encap:Ethernet
inet addr:192.168.0.193 Bcast:192.168.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:197673563 errors:0 dropped:0 overruns:0 frame:0
TX packets:16035978 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:3387168854 (3.1 GiB) TX bytes:1675434171 (1.5 GiB)
Interrupt:26 Base address:0xc000

lo Link encap:Local Loopback
inet addr:127.0.0.1 Mask:255.0.0.0
UP LOOPBACK RUNNING MTU:16436 Metric:1
RX packets:1382549 errors:0 dropped:0 overruns:0 frame:0
TX packets:1382549 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:0
RX bytes:235307388 (224.4 MiB) TX bytes:235307388 (224.4 MiB)eth0: negotiated 100baseTx-FD flow-control, link ok
product info: vendor 00:07:32, model 17 rev 2
basic mode: autonegotiation enabled
basic status: autonegotiation complete, link ok
capabilities: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD
advertising: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
link partner: 100baseTx-FD 100baseTx-HD 10baseT-FD 10baseT-HD flow-control
NIC statistics:
tx_packets: 16036032
rx_packets: 197673571
tx_errors: 0
rx_errors: 6
rx_missed: 0
align_errors: 5
tx_single_collisions: 0
tx_multi_collisions: 0
unicast: 197637052
broadcast: 30059
multicast: 6460
tx_aborted: 0
tx_underrun: 0
Kernel Interface table
Iface MTU Met RX-OK RX-ERR RX-DRP RX-OVR TX-OK TX-ERR TX-DRP TX-OVR Flg
eth0 1500 0 197673571 0 0 0 16036033 0 0 0 BMRU
lo 16436 0 1382770 0 0 0 1382770 0 0 0 LRU
 
  


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