HW acceleration on RT-N66U

[jobongo]

I did some testing with a NAS that sits on the WAN side of my RT-N66U to see the speed difference that hardware acceleration made. I did large file copying to a PC that was on the LAN side to the N66U. With hardware acceleration on, I would get speeds that averaged ~65 MB/s (520 Mb/s). With hardware acceleration off, the speeds dropped to a ~15 MB/s (120Mb/s) average. That is a big drop but if you were simply using the WAN for internet that would still be a 120 Mb/s internet connection that could be supported without hardware acceleration. Take into consideration though that the test I did was with only once TCP connection established to the NAS. I would assume that there were more sessions then the total throughput would go down but this would be the case anyways on a limited bandwidth WAN connection.

 

[RussellInCincinnati]

What a helpful post. Now we know that turning off hardware acceleration, so that you can use quality of service throttling (or bandwidth reservation) for certain internet users, or so that you can use packet-filtering/blocking features, isn't going to "hurt" internet access speeds. Until someone has an internet connection faster than 120 megabits per second.

 

[joegreat]

With hardware acceleration off, the speeds dropped to a ~15 MB/s (120Mb/s) average. That is a big drop but if you were simply using the WAN for internet that would still be a 120 Mb/s internet connection that could be supported without hardware acceleration.

Hi,

Any idea about the CPU load without HW acc.?
Having Transmission (or other features) running on CPU might overload the Broadcom 470 @ 600MHz very easily...

Then the throughput my drop dramatically!

With kind regards
Josip

 

[jobongo]

I do know that the CPU load went up as it should do. I don't have any exact figures but I remember keeping an eye on it. Honestly, my personal opinion is this broadcom chip should do just fine even with transmission and other services though I have to agree that running additional services would probably decrease the lan/wan throughput. By how much, I don't know

As with any computer, more processes means more processing power needed.

 

[M.T.Field]

Hey Jobongo - thank you SO MUCH for an actual data point. Like Russell, my ISP comes nowhere near the 120 mbps mark, so I think I'm good leaving per-ip traffic monitoring on. Also, when using networked games that report latency, I haven't seen any increase in the reported figures.

 

[jobongo]

Not a problem. Glad I could help.

 

[Werthe]

I did a quick test couple of days ago with Merlin 3.0.0.4_270.25b & RT-AC66U. I was able to get 250Mbps download speed with HW acceleration disabled and 320-330Mbps with HW acceleration enabled. My router is connected to a cable modem that is in bridged mode.

 

[RussellInCincinnati]

Thanks Werthe. Well it looks like the issue is settled that you get faster-than-almost-all-internet-connections WAN routing speed for your $190 U.S. dollar purchase in 2013, whether you use "hardware acceleration" or not. My own clients are extremely happy at the ease of turning off hardware accel, with no noticeable loss of anything, and thus being able to reserve internet bandwidth for their internet telephone call devices.

Fascinating how much use we can all get out of these tiny, low-power CPU's. Some of my word-processing-type clients are impressed that for their money their nice WiFi transmitter even can get 10 megabytes per second read speed out of flash drives on the wrtMerlin USB ports. And thus they can throw away their power-hungry old file servers.

 

[Werthe]

Today I did some more testing since there is clearly some interest about the capabilites without HW acceleration. Without HW acceleration I was able to get over 200Mbps download every time but the lack of HW acceleration starts to show after 200Mbps. I did get 210-220Mbps 90% of the time but 220-250Mbps was not that easy. This was done with Cat 6 cable PC to Router and without QoS. Merlin 3.0.0.4_270.25b & RT-AC66U.

After enabling HW acceleration it goes over 300Mbps. The connection is 350Mbps and best download speed is 330+Mbps.

For me the extra 100Mbps is worth keeping the HW Acceleration on, but it doesn't seem to affect internet speeds up to 200Mbps. Ping was the same 0ms no matter if HW acceleration was on or off.

 

[RMerlin]

I wish Broadcom would open the CTF source code. Can't imagine what is so confidential there to make them keep that as a closed-sourced binary blob.

Because of this, nobody even knows for sure what it exactly do. We know it has something to do with forwarding packets for already established connections (they call it Cut Through Forwarding), but who knows what else is also going on there.

The fact it's a closed blackbox also means we can't tell for sure what's compatible with it and what isn't.

 

[RussellInCincinnati]

(unimportant side comment) Werthe do you just have a whole bunch faster internet connection than most of us U.S. mortals? Or are you saying that you're using the Asus router WAN port to simply bridge between 2 gigabit networks, thus making it easy for you to come up with 330 megabit per second traffic through the Asus WAN port?

 

[Werthe]

(unimportant side comment) Werthe do you just have a whole bunch faster internet connection than most of us U.S. mortals?...

Don't really know how fast internet connections you have there nowadays, but here in Finland over 600 000 households (consider that we only have about 5 million people here) can have this connection from one ISP + there are other providers with fast connections. My ISP is actually testing 1,6 Gigabit internet connections right now... so yes.. 350Mbps is my internet connection.

When I studied in St.Louis in 2004 I had 100/100Mbps internet connection and I wasn't complaining. It was quite fast back then

 

[CBMC]

Don't really know how fast internet connections you have there nowadays, but here in Finland over 600 000 households (consider that we only have about 5 million people here) can have this connection from one ISP + there are other providers with fast connections. My ISP is actually testing 1,6 Gigabit internet connections right now... so yes.. 350Mbps is my internet connection.

When I studied in St.Louis in 2004 I had 100/100Mbps internet connection and I wasn't complaining. It was quite fast back then

St. Louis, MO? I have a 30/4 Mbps here in St. Louis. You must have been paying quite a bit or been on a school line with a very fast connection.

Sent from my Nexus 7 using Tapatalk 2

 

[jobongo]

Werthe,

I would like to use QoS but I have offloaded that onto another device to get the throughput that I need. I have a similar setup; Shielded CAT6 throughout the house and CAT6 FUTP connected to each device but the limitations of 120Mb/s is all I could get. Did you change the WAN interface to accept jumbo frames or make any other tweak? Probably wouldn't matter on the ISP side. The only thing that I can see different from my tests are that you are using .25b firmware where I used .24.

Merlin,

Are there any changes in the .25b firmware that would enhance throughput without hardware acceleration?

Thanks

 

[RMerlin]

Merlin,

Are there any changes in the .25b firmware that would enhance throughput without hardware acceleration?

Thanks

No change at all, at least in terms of plain throughput. The optimizations were strictly related to SSL and OpeNVPN.

 

[Werthe]

CBMC: They were apartments near the University of Missouri-St. Louis. The rent for the apartment was quite high (common swimming pool, volleyball court etc.) but the internet was not that expensive and I was splitting the costs with my girlfriend (wife nowadays). The 100/100Mbps was not for one apartment only, so the real speed was depending on how many users would be online and what they would do. My 350Mbps connection is for one household.

jobongo: I have shielded Draka CAT7 Duplex 900MHz throughout the house but that should not make any difference. I have cat 6 cable between the wall and my PC anyways. The differences could be RT-N66U vs. RT-AC66U, the cable modem, computer or even ISP (who knows). My cable modem is Cisco EPC3825 in bridged mode and I'm using a RT-AC66U as I said earlier. The default MTU in the modem is 1500. I don't have to make any special tweaks to get over 200Mbps HW acceleration off or 330Mbps HW acceleration on.

As RMerlin said, we don't exactly know what Cut Through Forwarding (HW acceleration) does and how is the compatibility.

The strange thing is that I tried several DD-WRT test versions but was not able to get over 100-110Mbps internet speeds. It was like hitting a wall in the 110 mark. It does not support the HW acceleration since broadcom doesn't want to give the sourcecodes. Don't really know if the reason for the "slow" internet speed was the lack of CTF support, some sort of incompatibility with my cable modem, bug, or just a wrong setting somewhere that I could not find.

 

[jobongo]

Werthe

Ok I didn't see that you were using the AC66U. I guess I should have read more closely. I am using the N66U. I am going to do some more tests to try and get the most throughput without HW acceleration.

 

[iissmart]

The complete list of things that can cause it to be disabled:

if(nvram_get_int("cstats_enable") || nvram_get_int("qos_enable") || 
nvram_get_int("url_enable_x") || nvram_get_int("keyword_enable_x") || nvram_get_int("ctf_disable_force")

Plus add being in Repeater mode.

I have none of the above enabled yet it still says HW Acceleration Disabled (incompatible feature enabled). Is there anything else to check?

I have a 100/20 cable connection and am noticing high packet loss. Not sure if it's the router (AC66U) or just my connection.

Running the new Asuswrt-Merlin 3.0.0.4.354.27 Beta 1.

 

[RMerlin]

I have none of the above enabled yet it still says HW Acceleration Disabled (incompatible feature enabled). Is there anything else to check?

I have a 100/20 cable connection and am noticing high packet loss. Not sure if it's the router (AC66U) or just my connection.

Running the new Asuswrt-Merlin 3.0.0.4.354.27 Beta 1.

If it says "incompatible feature enabled", then you definitely have something enabled that forces it to disable HW acceleration, unless it's the Sysinfo page that fails to properly load for you (in which case it might never run the code meant to hide that message). Open your web browser console and look for any error after reloading the page.

 

[iissmart]

If it says "incompatible feature enabled", then you definitely have something enabled that forces it to disable HW acceleration, unless it's the Sysinfo page that fails to properly load for you (in which case it might never run the code meant to hide that message). Open your web browser console and look for any error after reloading the page.

It was because IPv6 (native) was enabled. I posted in the beta build thread.