Thread (52 messages) 52 messages, 10 authors, 2012-06-06

Re: Strange latency spikes/TX network stalls on Sun Fire X4150(x86) and e1000e

From: Denys Fedoryshchenko <hidden>
Date: 2012-05-18 14:04:36

It seems logic in BQL has serious issues. The most bad thing, if 
someone don't want limits (especially low as this),
there is no way to disable BQL in Kernel configuration, only tuning 
each interface over sysfs values.

I just did short debug:
if (limit != dql->limit) {
+                printk("New limit %d\n", dql->limit);
                 dql->limit = limit;
                 ovlimit = 0;
}

And got this numbers:
[   18.696839] New limit 0
[   19.622967] New limit 42
[   20.037810] New limit 165
[   35.473666] New limit 386
[   37.418591] New limit 1374
[   37.420064] New limit 6432
[   39.209480] New limit 16548
[   39.214773] New limit 1704
[   40.696065] New limit 6762
[   40.696390] New limit 15564
[   41.921120] New limit 25788
[   41.921165] New limit 388
[   42.696286] New limit 534
[   42.696539] New limit 1096
[   42.696719] New limit 2304
[   53.360394] New limit 24334
[   54.696072] New limit 484
[   54.696135] New limit 934

This means sometimes limit goes below MTU, and till queue limit 
increased, i will see this traffic "stalled",
if there is large packet in queue. Probably BQL miscalculate queue as 
full because of some specific handling
of sent packets in e1000e on this specific hardware. Because it should 
not be full, it is 1Gbps wire,
and it is empty. So in result, instead of eliminating latency, it is 
adding it.

I can make a patch that will make minimum BQL value not less than MTU + 
overhead, is it ok like this?
Probably it will solve issue, but it is more workaround and safety 
fuse, than a solution.

On 2012-05-17 19:54, Denys Fedoryshchenko wrote:
Also i notice, limit constantly changing over time (even i am not
touching it).

centaur ~ # grep "" 
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/*
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/hold_time:1000
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/inflight:0
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/limit:13018

/sys/class/net/eth0/queues/tx-0/byte_queue_limits/limit_max:1879048192
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/limit_min:0
centaur ~ # grep "" 
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/*
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/hold_time:1000
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/inflight:4542
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/limit:13018

/sys/class/net/eth0/queues/tx-0/byte_queue_limits/limit_max:1879048192
/sys/class/net/eth0/queues/tx-0/byte_queue_limits/limit_min:0

Is it supposed to be like this?

On 2012-05-17 16:42, Denys Fedoryshchenko wrote:
quoted
Found commit that cause problem:

author	Tom Herbert [off-list ref]
Mon, 28 Nov 2011 16:33:16 +0000 (16:33 +0000)
committer	David S. Miller [off-list ref]
Tue, 29 Nov 2011 17:46:19 +0000 (12:46 -0500)
commit	3f0cfa3bc11e7f00c9994e0f469cbc0e7da7b00c
tree	d6670a4f94b2b9dedacc38edb6f0e1306b889f6b	tree | snapshot
parent	114cf5802165ee93e3ab461c9c505cd94a08b800	commit | diff
e1000e: Support for byte queue limits

Changes to e1000e to use byte queue limits.

Signed-off-by: Tom Herbert <redacted>
Acked-by: Eric Dumazet <redacted>
Signed-off-by: David S. Miller <davem@davemloft.net>

If i reverse it, problem disappearing.

How i reproduce it:
In two consoles do "fast" ping to nearby host
ping 194.146.XXX.XXX -s1472 -i0.0001
ping 194.146.XXX.XXX -s1472 -i0.1

For third open ssh to host with "problem", open mcedit, and just
scroll down large text file.
After few seconds some "stalls" will occur, and in ping history i 
can see:
1480 bytes from 194.146.153.7: icmp_req=1797 ttl=64 time=0.161 ms
1480 bytes from 194.146.153.7: icmp_req=1798 ttl=64 time=0.198 ms
1480 bytes from 194.146.153.7: icmp_req=1799 ttl=64 time=0.340 ms
1480 bytes from 194.146.153.7: icmp_req=1800 ttl=64 time=0.381 ms
1480 bytes from 194.146.153.7: icmp_req=1801 ttl=64 time=914 ms
1480 bytes from 194.146.153.7: icmp_req=1802 ttl=64 time=804 ms
1480 bytes from 194.146.153.7: icmp_req=1803 ttl=64 time=704 ms
1480 bytes from 194.146.153.7: icmp_req=1804 ttl=64 time=594 ms
1480 bytes from 194.146.153.7: icmp_req=1805 ttl=64 time=0.287 ms
1480 bytes from 194.146.153.7: icmp_req=1806 ttl=64 time=0.226 ms


If i apply small patch - problem will disappear. Sure it is not a
solution, but
let me know how i can help to debug problem more.
--- netdev.c    2012-05-12 20:08:37.000000000 +0300
+++ netdev.c.patched    2012-05-17 16:32:28.895760472 +0300
@@ -1135,7 +1135,7 @@

        tx_ring->next_to_clean = i;

-       netdev_completed_queue(netdev, pkts_compl, bytes_compl);
+//     netdev_completed_queue(netdev, pkts_compl, bytes_compl);

 #define TX_WAKE_THRESHOLD 32
        if (count && netif_carrier_ok(netdev) &&
@@ -2263,7 +2263,7 @@
                e1000_put_txbuf(adapter, buffer_info);
        }

-       netdev_reset_queue(adapter->netdev);
+//     netdev_reset_queue(adapter->netdev);
        size = sizeof(struct e1000_buffer) * tx_ring->count;
        memset(tx_ring->buffer_info, 0, size);
@@ -5056,7 +5056,7 @@
        /* if count is 0 then mapping error has occurred */
        count = e1000_tx_map(adapter, skb, first, max_per_txd,
nr_frags, mss);
        if (count) {
-               netdev_sent_queue(netdev, skb->len);
+//             netdev_sent_queue(netdev, skb->len);
                e1000_tx_queue(adapter, tx_flags, count);
                /* Make sure there is space in the ring for the next 
send. */
                e1000_maybe_stop_tx(netdev, MAX_SKB_FRAGS + 2);



On 2012-05-15 17:15, Denys Fedoryshchenko wrote:
quoted
Hi

I have two identical servers, Sun Fire X4150, both has different
flavors of Linux, x86_64 and i386.
04:00.0 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit
Ethernet Controller (Copper) (rev 01)
04:00.1 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit
Ethernet Controller (Copper) (rev 01)
0b:00.0 Ethernet controller: Intel Corporation 82571EB Gigabit
Ethernet Controller (rev 06)
0b:00.1 Ethernet controller: Intel Corporation 82571EB Gigabit
Ethernet Controller (rev 06)
I am using now interface:
#ethtool -i eth0
driver: e1000e
version: 1.9.5-k
firmware-version: 2.1-11
bus-info: 0000:04:00.0
There is 2 CPU , Intel(R) Xeon(R) CPU           E5440  @ 2.83GHz .

i386 was acting as NAT and shaper, and as soon as i removed shaper
from it, i started to experience strange lockups, e.g. traffic is
normal for 5-30 seconds, then short lockup for 500-3000ms (usually
around 1000ms) with dropped packets counter increasing. I was
suspecting it is due load, but it seems was wrong.
Recently, on another server, x86_64 i am using as development, i
upgrade kernel (it was old, from 2.6 series) and on completely idle
machine started to experience same latency spikes, while i am just
running mc and for example typing in text editor - i notice 
"stalls".
After i investigate it a little more, i notice also small amount of
drops on interface. No tcpdump running. Also this machine is idle, 
and
the only traffic there - some small broadcasts from network, my 
ssh,
and ping.

Dropped packets in ifconfig
          RX packets:3752868 errors:0 dropped:5350 overruns:0 
frame:0
Counter is increasing sometimes, when this stall happening.

ethtool -S is clean, there is no dropped packets.

I did tried to check load (mpstat and perf), there is nothing
suspicious, latencytop also doesn't show anything suspicious.
dropwatch report a lot of drops, but mostly because there is some
broadcasts and etc. tcpdump at the moment of such drops doesn't 
show
anything suspicious.
Changed qdisc from default fifo_fast to bfifo, without any result.
Tried:  ethtool -K eth0 tso off gso off gro off sg off , no result
Problem occured at 3.3.6 - 3.4.0-rc7, most probably 3.3.0 also, but 
i
don't remember for sure. I thik on some kernels like 3.1 probably 
it
doesn't occur, i will check it soon, because it is not always 
reliable
to reproduce it. All tests i did on 3.4.0-rc7.

I did run also in background tcpdump, additionally iptables with
timestamps, and at time when stall occured, seems i am still 
receiving
packets properly, also on iperf udp  (from some host to this 
SunFire)
at this moments no packets missing. But i am sure RX interface 
errors
are increasing.
If i do iperf from SunFire to test host - there is packetloss at
moments when stall occured.

I suspect that by some reason network card stop to transmit, but
unable to pinpoint issue. All other hosts in this network are fine 
and
don't have such problems.
Can you help me with that please? Maybe i can provide more debug
information, compile with patches and etc. Also i will try to 
fallback
to 3.1 and 3.0 kernels.

Here it is how it occurs and i am reproducing it:
I'm just opening file, and start to scroll it in mc, then in 
another
console i run ping
[1337089061.844167] 1480 bytes from 194.146.153.20: icmp_req=162
ttl=64 time=0.485 ms
[1337089061.944138] 1480 bytes from 194.146.153.20: icmp_req=163
ttl=64 time=0.470 ms
[1337089062.467759] 1480 bytes from 194.146.153.20: icmp_req=164
ttl=64 time=424 ms
[1337089062.467899] 1480 bytes from 194.146.153.20: icmp_req=165
ttl=64 time=324 ms
[1337089062.468058] 1480 bytes from 194.146.153.20: icmp_req=166
ttl=64 time=214 ms
[1337089062.468161] 1480 bytes from 194.146.153.20: icmp_req=167
ttl=64 time=104 ms
[1337089062.468958] 1480 bytes from 194.146.153.20: icmp_req=168
ttl=64 time=1.15 ms
[1337089062.568604] 1480 bytes from 194.146.153.20: icmp_req=169
ttl=64 time=0.477 ms
[1337089062.668909] 1480 bytes from 194.146.153.20: icmp_req=170
ttl=64 time=0.667 ms

Remote host tcpdump:
1337089061.934737 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 163, length 1480
1337089062.458360 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 164, length 1480
1337089062.458380 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 164, length 1480
1337089062.458481 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 165, length 1480
1337089062.458502 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 165, length 1480
1337089062.458606 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 166, length 1480
1337089062.458623 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 166, length 1480
1337089062.458729 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 167, length 1480
1337089062.458745 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 167, length 1480
1337089062.459537 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 168, length 1480
1337089062.459545 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 168, length 1480

Local host(SunFire) tcpdump:
1337089061.844140 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 162, length 1480
1337089061.943661 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 163, length 1480
1337089061.944124 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 163, length 1480
1337089062.465622 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 164, length 1480
1337089062.465630 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 165, length 1480
1337089062.465632 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 166, length 1480
1337089062.465634 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 167, length 1480
1337089062.467730 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 164, length 1480
1337089062.467785 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 168, length 1480
1337089062.467884 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 165, length 1480
1337089062.468035 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 166, length 1480
1337089062.468129 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 167, length 1480
1337089062.468928 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 168, length 1480
1337089062.568112 IP 194.146.153.22 > 194.146.153.20: ICMP echo
request, id 3486, seq 169, length 1480
1337089062.568578 IP 194.146.153.20 > 194.146.153.22: ICMP echo
reply, id 3486, seq 169, length 1480

lspci -t
centaur src # lspci -t
-[0000:00]-+-00.0
           +-02.0-[01-05]--+-00.0-[02-04]--+-00.0-[03]--
           |               |               \-02.0-[04]--+-00.0
           |               |                            \-00.1
           |               \-00.3-[05]--
           +-03.0-[06]--
           +-04.0-[07]----00.0
           +-05.0-[08]--
           +-06.0-[09]--
           +-07.0-[0a]--
           +-08.0
           +-10.0
           +-10.1
           +-10.2
           +-11.0
           +-13.0
           +-15.0
           +-16.0
           +-1c.0-[0b]--+-00.0
           |            \-00.1
           +-1d.0
           +-1d.1
           +-1d.2
           +-1d.3
           +-1d.7
           +-1e.0-[0c]----05.0
           +-1f.0
           +-1f.1
           +-1f.2
           \-1f.3
lspci
00:00.0 Host bridge: Intel Corporation 5000P Chipset Memory
Controller Hub (rev b1)
00:02.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI 
Express
x4 Port 2 (rev b1)
00:03.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI 
Express
x4 Port 3 (rev b1)
00:04.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI 
Express
x8 Port 4-5 (rev b1)
00:05.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI 
Express
x4 Port 5 (rev b1)
00:06.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI 
Express
x8 Port 6-7 (rev b1)
00:07.0 PCI bridge: Intel Corporation 5000 Series Chipset PCI 
Express
x4 Port 7 (rev b1)
00:08.0 System peripheral: Intel Corporation 5000 Series Chipset 
DMA
Engine (rev b1)
00:10.0 Host bridge: Intel Corporation 5000 Series Chipset FSB
Registers (rev b1)
00:10.1 Host bridge: Intel Corporation 5000 Series Chipset FSB
Registers (rev b1)
00:10.2 Host bridge: Intel Corporation 5000 Series Chipset FSB
Registers (rev b1)
00:11.0 Host bridge: Intel Corporation 5000 Series Chipset Reserved
Registers (rev b1)
00:13.0 Host bridge: Intel Corporation 5000 Series Chipset Reserved
Registers (rev b1)
00:15.0 Host bridge: Intel Corporation 5000 Series Chipset FBD
Registers (rev b1)
00:16.0 Host bridge: Intel Corporation 5000 Series Chipset FBD
Registers (rev b1)
00:1c.0 PCI bridge: Intel Corporation 631xESB/632xESB/3100 Chipset
PCI Express Root Port 1 (rev 09)
00:1d.0 USB controller: Intel Corporation 631xESB/632xESB/3100
Chipset UHCI USB Controller #1 (rev 09)
00:1d.1 USB controller: Intel Corporation 631xESB/632xESB/3100
Chipset UHCI USB Controller #2 (rev 09)
00:1d.2 USB controller: Intel Corporation 631xESB/632xESB/3100
Chipset UHCI USB Controller #3 (rev 09)
00:1d.3 USB controller: Intel Corporation 631xESB/632xESB/3100
Chipset UHCI USB Controller #4 (rev 09)
00:1d.7 USB controller: Intel Corporation 631xESB/632xESB/3100
Chipset EHCI USB2 Controller (rev 09)
00:1e.0 PCI bridge: Intel Corporation 82801 PCI Bridge (rev d9)
00:1f.0 ISA bridge: Intel Corporation 631xESB/632xESB/3100 Chipset
LPC Interface Controller (rev 09)
00:1f.1 IDE interface: Intel Corporation 631xESB/632xESB IDE
Controller (rev 09)
00:1f.2 SATA controller: Intel Corporation 631xESB/632xESB SATA 
AHCI
Controller (rev 09)
00:1f.3 SMBus: Intel Corporation 631xESB/632xESB/3100 Chipset SMBus
Controller (rev 09)
01:00.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express
Upstream Port (rev 01)
01:00.3 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express 
to
PCI-X Bridge (rev 01)
02:00.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express
Downstream Port E1 (rev 01)
02:02.0 PCI bridge: Intel Corporation 6311ESB/6321ESB PCI Express
Downstream Port E3 (rev 01)
04:00.0 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit
Ethernet Controller (Copper) (rev 01)
04:00.1 Ethernet controller: Intel Corporation 80003ES2LAN Gigabit
Ethernet Controller (Copper) (rev 01)
07:00.0 RAID bus controller: Adaptec AAC-RAID (rev 09)
0b:00.0 Ethernet controller: Intel Corporation 82571EB Gigabit
Ethernet Controller (rev 06)
0b:00.1 Ethernet controller: Intel Corporation 82571EB Gigabit
Ethernet Controller (rev 06)
0c:05.0 VGA compatible controller: ASPEED Technology, Inc. ASPEED
Graphics Family


dmesg:
[    4.936885] e1000: Intel(R) PRO/1000 Network Driver - version
7.3.21-k8-NAPI
[    4.936887] e1000: Copyright (c) 1999-2006 Intel Corporation.
[    4.936966] e1000e: Intel(R) PRO/1000 Network Driver - 1.9.5-k
[    4.936967] e1000e: Copyright(c) 1999 - 2012 Intel Corporation.
[    4.938529] e1000e 0000:04:00.0: (unregistered net_device):
Interrupt Throttling Rate (ints/sec) set to dynamic conservative 
mode
[    4.939598] e1000e 0000:04:00.0: irq 65 for MSI/MSI-X
[    4.992246] e1000e 0000:04:00.0: eth0: (PCI 
Express:2.5GT/s:Width
x4) 00:1e:68:04:99:f8
[    4.992657] e1000e 0000:04:00.0: eth0: Intel(R) PRO/1000 Network
Connection
[    4.992964] e1000e 0000:04:00.0: eth0: MAC: 5, PHY: 5, PBA No: 
FFFFFF-0FF
[    4.994745] e1000e 0000:04:00.1: (unregistered net_device):
Interrupt Throttling Rate (ints/sec) set to dynamic conservative 
mode
[    4.996233] e1000e 0000:04:00.1: irq 66 for MSI/MSI-X
[    5.050901] e1000e 0000:04:00.1: eth1: (PCI 
Express:2.5GT/s:Width
x4) 00:1e:68:04:99:f9
[    5.051317] e1000e 0000:04:00.1: eth1: Intel(R) PRO/1000 Network
Connection
[    5.051623] e1000e 0000:04:00.1: eth1: MAC: 5, PHY: 5, PBA No: 
FFFFFF-0FF
[    5.051857] e1000e 0000:0b:00.0: Disabling ASPM  L1
[    5.052168] e1000e 0000:0b:00.0: (unregistered net_device):
Interrupt Throttling Rate (ints/sec) set to dynamic conservative 
mode
[    5.052611] e1000e 0000:0b:00.0: irq 67 for MSI/MSI-X
[    5.223454] e1000e 0000:0b:00.0: eth2: (PCI 
Express:2.5GT/s:Width
x4) 00:1e:68:04:99:fa
[    5.223864] e1000e 0000:0b:00.0: eth2: Intel(R) PRO/1000 Network
Connection
[    5.224178] e1000e 0000:0b:00.0: eth2: MAC: 0, PHY: 4, PBA No: 
C83246-002
[    5.224412] e1000e 0000:0b:00.1: Disabling ASPM  L1
[    5.224709] e1000e 0000:0b:00.1: (unregistered net_device):
Interrupt Throttling Rate (ints/sec) set to dynamic conservative 
mode
[    5.225168] e1000e 0000:0b:00.1: irq 68 for MSI/MSI-X
[    5.397603] e1000e 0000:0b:00.1: eth3: (PCI 
Express:2.5GT/s:Width
x4) 00:1e:68:04:99:fb
[    5.398021] e1000e 0000:0b:00.1: eth3: Intel(R) PRO/1000 Network
Connection
[    5.398336] e1000e 0000:0b:00.1: eth3: MAC: 0, PHY: 4, PBA No: 
C83246-002
[   13.859817] e1000e 0000:04:00.0: irq 65 for MSI/MSI-X
[   13.962309] e1000e 0000:04:00.0: irq 65 for MSI/MSI-X
[   17.150392] e1000e: eth0 NIC Link is Up 1000 Mbps Full Duplex,
Flow Control: None

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---
Network engineer
Denys Fedoryshchenko

Dora Highway - Center Cebaco - 2nd Floor
Beirut, Lebanon
Tel:	+961 1 247373
E-Mail: denys@visp.net.lb
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More majordomo info at  http://vger.kernel.org/majordomo-info.html
---
Network engineer
Denys Fedoryshchenko

Dora Highway - Center Cebaco - 2nd Floor
Beirut, Lebanon
Tel:	+961 1 247373
E-Mail: denys@visp.net.lb
--
To unsubscribe from this list: send the line "unsubscribe netdev" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
---
Network engineer
Denys Fedoryshchenko

Dora Highway - Center Cebaco - 2nd Floor
Beirut, Lebanon
Tel:	+961 1 247373
E-Mail: denys@visp.net.lb

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