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Hi all. Sorry in advance for the rash of emails today but the topics |
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seem to be varying and hopefully folks will read only the ones they |
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think they could help with. |
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QUESTIONS: |
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1) What causes a 'collision' on a network interface? |
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2) How can I eliminate them? (Including hardware changes if required.) |
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In looking at this MythTV problem it looks like it's possibly the |
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networking/NFS side of the equation and not the PVR software side. I'm |
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running a test using my local drive right now to see if that's true. |
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In looking at the networking side i see a problem with collisions: |
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|
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dragonfly ~ # ifconfig |
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eth0 Link encap:Ethernet HWaddr 00:40:CA:74:21:E9 |
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inet addr:192.168.1.55 Bcast:192.168.1.255 Mask:255.255.255.0 |
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UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 |
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RX packets:4014229 errors:0 dropped:0 overruns:0 frame:0 |
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TX packets:4014933 errors:0 dropped:0 overruns:0 carrier:0 |
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collisions:1808957 txqueuelen:1000 |
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RX bytes:17072649 (16.2 Mb) TX bytes:3375271889 (3218.9 Mb) |
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Interrupt:20 Base address:0x9000 |
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|
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myth14 ~ # ifconfig |
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eth0 Link encap:Ethernet HWaddr 00:11:D8:F4:CD:1D |
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inet addr:192.168.1.14 Bcast:192.168.1.255 Mask:255.255.255.0 |
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UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1 |
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RX packets:1732167 errors:0 dropped:0 overruns:0 frame:0 |
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TX packets:1592861 errors:0 dropped:0 overruns:0 carrier:0 |
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collisions:289582 txqueuelen:1000 |
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RX bytes:1645387797 (1569.1 Mb) TX bytes:1558513991 (1486.3 Mb) |
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Interrupt:18 Base address:0xec00 |
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Myth14 is the NFS server. Dragonfly is the NFS client that mounts the |
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drive. I do not see any collisions on other machines on my network. |
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Ethernet hardware is built-in to both machines: |
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|
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dragonfly ~ # lspci | grep Ethernet |
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0000:01:03.0 Ethernet controller: Realtek Semiconductor Co., Ltd. |
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RTL-8139/8139C/8139C+ (rev 10) |
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dragonfly ~ # |
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myth14 ~ # lspci | grep Ethernet |
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0000:02:08.0 Ethernet controller: 3Com Corporation 3Com 3C920B-EMB-WNM |
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Integrated Fast Ethernet Controller (rev 40) |
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myth14 ~ # |
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|
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The two machines are connected through a small LinkSys switch. model EZXS55W: |
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|
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http://www.linksys.com/servlet/Satellite?childpagename=US%2FLayout&packedargs=c%3DL_Product_C2%26cid%3D1115416836711&pagename=Linksys%2FCommon%2FVisitorWrapper |
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The URL probably won't survive the email. |
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If I run hdparm -tT on the NFS drive it is using DMA but it's slow, as |
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it's always been: |
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myth14 ~ # hdparm -tT /dev/hdc |
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|
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/dev/hdc: |
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Timing cached reads: 1544 MB in 2.00 seconds = 771.73 MB/sec |
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Timing buffered disk reads: 46 MB in 3.11 seconds = 14.77 MB/sec |
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myth14 ~ # |
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I'm going to investigate a new kernel on the NFS server side, althoguh |
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I'm loth to do this since it means messing with LIRC, fglrx and lots |
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of other touchy stuff. However, if there is a simple way to configure |
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things so that collisions disappear or go down significantly that |
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would be great. |
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Again, thanks in advance and sorry for the number of emails. |
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Cheers, |
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Mark |
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-- |
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