Gigabit on Server Causing Slowdowns?

[peternm22]

This is a bit of a weird one.

Since upgrading to 7.1.xx betas, I've noticed that the UI on my HD300 can be a bit sluggish.

This is most noticeable with animations which are no longer "smooth". If I'm watching a recording and bring up the OSD, and close it down it is very jerky in it's motion. If I pause the video, and then try the OSD again it is very smooth.

I've tried both the beta and release firmwares on the HD300, and they both exhibit the same problems.

Running the HD300 network test that was posted a little while ago, the speeds show as consistently around 94-95mbps never dipping below that.

Upgraded to the latest network card driver on the server made no difference.

I was playing around with some of the advanced controls for the network adapter, and forced the network connection to 100mbps full duplex. Before it had been set to auto, which resulted in a 1000mbps connection to the router (which is a gigabit router).

Much to my surprise, all of the UI jerkiness on the HD300 has disappeared since doing this.

Does anyone know why this is? I know the HD300 only has a 100mbps port, so could the server just be trying to send too much info at a time to the HD300 causing it to choke?

I would prefer to have the server connected at gigabit speeds because of other computers on the network which actually do support that speed.

Motherboard is a Gigabyte GA-MA785GM-US2H, Windows 7 HP 64, 4GB RAM. SageTV java heap is set to 1000MB.

[Zuhkov]

Do you have the option to set to 1000mbps full duplex instead of Auto? If so, give that a try and see if it works as well as 100mbps full duplex. The critical setting is forcing full duplex. It's likely the NIC was setting itself to 1000mbps half duplex. When set that way, it won't transmit while it's receiving (and vice versa), so if you were browsing the web on that computer (or some other activity where that computer is receiving data over the network) while watching something on the extender, it could interfere with the video transmission.

[peternm22]

Thanks for the suggestion, but setting it to 1 Gbps full duplex resulted in the same jerky UI as before. Reverting back to 100 Mbps full duplex fixed this once again.

There are about a dozen other settings in the device manager for the network adapter, could one of them have some effect? I don't know what most of them do so I don't really want to mess around with them. Here are the options and current settings:

Auto Disable Gigabit (PowerSaving): Disabled
Flow Control: Disabled
Interrupt Moderation: Enabled
IPv4 Checksum Offload: Rx & Tx Enabled
Jumbo Frame: Disabled
Large Send Offload (IPv4): Enabled
Large Send Offload v2 (IPv6): Enabled
Network Address: Not Present
Priority & VLAN: Priority & VLAN Enabled
Receive Buffers: 512
Speed & Duplex: 100 Mbps Full Duplex
TCP Checksum Offload (IPv4): Rx & Tx Enabled
TCP Checksum Offload (IPv6): Rx & Tx Enabled
Transmit Buffers: 128
UDP Checksum Offload (IPv4): Rx & Tx Enabled
UDP Checksum Offload (IPv6): Rx & Tx Enabled
Wake on Magic Packet: Enabled
Wake on pattern match: Enabled

[Zuhkov]

What kind of router and switches is this connection passing through?

It may be that the extender and computer are failing to negotiate a full duplex gigabit connection and then the computer falls back to half duplex gigabit (or even half duplex 100mbps) instead of full duplex 100mbps. I know you'd prefer to use gigabit since other devices on your network support it, but are you at a point traffic-wise where you ever max out 100mpbs duplex? That's over 12 megabytes a second in each direction.

[GKusnick]

Originally Posted by Zuhkov

It may be that the extender and computer are failing to negotiate a full duplex gigabit connection...

Wouldn't that negotiation happen between the extender and the router, and then separately between the server and the router?

My hunch is that the problem is most likely to be in the router's gigabit implementation rather than anything in the extender or server NIC. If you have a separate gigabit switch (or can borrow one), try putting it between the server and the extender, so that none of the extender traffic flows through the router. If the problem persists, then the router is not the culprit.

[peternm22]

It's an ASUS RT-N16 router running the Tomato firmware. I don't have any other gigabit switches/routers to try.

[MattHelm]

Originally Posted by peternm22

Flow Control: Disabled

I'm not sure that is correct???

[peternm22]

Originally Posted by MattHelm

I'm not sure that is correct???

Just tried enabling flow control and it works! Server is connected at 1Gbps and no jerkiness on the HD300.

Just out of pure curiosity, any idea why it works? I did a quick search on the forum about "flow control" and most of the posts I saw say that disabling it actually FIXES their problems.

[GKusnick]

According to this Wikipedia article, flow control is discouraged because it can decrease the performance of the entire network by stopping all traffic until the slow node catches up.

The fact that it works for you suggests to me that it's a router issue. Without flow control, your router can't keep up with traffic coming from the server and drops packets, requiring a retransmit by the server, lowering overall throughput. Turning on flow control forces the server to wait for the router to digest each packet before sending out the next. This results in fewer dropped packets, but at the expense of throttling the server back to less than full gigabit speed.

This is guesswork on my part, of course, but it seems plausible. The test would be (as I suggested before) to swap in a more capable switch or router to see if that clears up the issue without resorting to flow control. If that's not an option for you, then I guess flow control is your next best solution.

[Zuhkov]

Glad that fixed your problem, but very interesting. I have the exact same router and I've never had that problem. I will say though that I run most of my traffic through a 24 port gigabit switch. I'll have to check my settings. In terms of specifications, I'm not sure there are more than a handful of routers that have the hardware to compete with the RT-16. Are you running TomatoUSB or a non-USB version of Tomato?

[peternm22]

I'm running Tomato USB, but not the latest release. I'm still running the release I installed when I first got the router last summer.

I'll try upgrading to the latest firmware build when I have a chance, but since I've been using the same firmware for quite a while I don't think that will be the problem.

I agree about the hardware specs on the router, this thing should be able to handle my network usage with ease.

[Fuzzy]

Honestly, your network performance/consistancy will likely increase getting a separate gigibit switch, and using the router just for routing internet. Most routers handle all switching in the CPU, which gets timeshared with any other processes you've got going on (which, if you're running tomato or dd-wrt, is probably a decent amount). a separate hardware switch will always work reliably, regardless of how burdened the router is.

[razrsharpe]

Originally Posted by peternm22

Since upgrading to 7.1.xx betas, I've noticed that the UI on my HD300 can be a bit sluggish.

This is most noticeable with animations which are no longer "smooth". If I'm watching a recording and bring up the OSD, and close it down it is very jerky in it's motion. If I pause the video, and then try the OSD again it is very smooth.

youre not alone... however i can't say when it started happening, what version of sage it was, etc. For me it is jerky the first time i bring up/close the osd... if i immediately bring it up again (or shortly there after) it is smooth... this is all while playback is active.

I at some point in the recent past disabled flow control... I'll try reenabling it and see if that fixes the non smooth animations i am seeing on the hd300. I do have a gigabit switch (HP 1410) that routes all the traffic so don't think my router is getting in the way...

[valnar]

Originally Posted by Zuhkov

Do you have the option to set to 1000mbps full duplex instead of Auto?

You should never set a gigabit adapter to 1000/Full unless you can set the switch to do the same. Hardcoding a NIC to 1000/Full is a sure-fire way to make the switch "negotiate" half-duplex.

[Zuhkov]

Originally Posted by valnar

You should never set a gigabit adapter to 1000/Full unless you can set the switch to do the same. Hardcoding a NIC to 1000/Full is a sure-fire way to make the switch "negotiate" half-duplex.

True, but that RT-16 should be capable of full duplex. I'd need to check my router settings, as I also run an RT-16 with TomatoUSB. I have not, however, experienced anything similar.

Is it possible that QoS is turned on and causing problems?

[peternm22]

My router usage is pretty basic. No QOS or optware stuff. The only non-basic features I use are:

-static DHCP setup for the server
-port forwarding for SageTV webserver and Placeshifter
-dynamic DNS updating service
-backup bandwidth stats to USB thumb drive (so they are not lost on router reboot)

My main reason for going to Tomato was stability. My last router was a combo unit from my ISP, and it liked to randomly reboot itself (killing the local network connectivity). I'm sitting at about 55 days uptime on the router right now, and it would be longer but we had a power outage then.

[Zuhkov]

Which build of Tomato are you using?

[peternm22]

I'm using build 48 from July 25, 2010. I think they are now up to build 54 now. I'll give the new one a shot when I get a chance.

[Fuzzy]

Even if you are using the router mostly for the lan traffic, it is still no where near as good at it as even a relatively cheap standalone switch. The process or in the routers is just not optimized for those kinds of datarates.

[peternm22]

Originally Posted by Fuzzy

Even if you are using the router mostly for the lan traffic, it is still no where near as good at it as even a relatively cheap standalone switch. The process or in the routers is just not optimized for those kinds of datarates.

I've tested this with only the server and HD300 connected to the router, with no other network traffic and it still exhibits the same problems. So I don't think it's a matter of the router not being able to handle it since that is a pretty light load (13-14mbps for the video stream, and a little bit more for the UI).