Intel Puma 6 Media Gateway Latency Problem

[thiggins]

Ed. Note: I moved this out of a different thread to its own.

Are you gonna cover the intel puma6 fiasco going on? Its effecting just about every 32 channel modem out there, seems weird no mentions of it here.
Here are the models it effects :

Arris:

TM1602A TG1642 TG1662A TG1672A TG2472G TG2492 (Virgin Media Hub 3)
TM1602G TG1662G TG1672G
TG1662S

DG1642 DG1660A DG1662G DG1670A DG2460A DG2470A
DG1670A/ACT
DTG1682G
MG2402
SB6190

AVM:

FRITZ!Box 6460 FRITZ!Box 6490

Cisco:

XG1-V3 DPC 3848 DPC 3848V DPC 3939
DPC3941B / DPC3941TÂ (commonly - Comcast Xfinity XB3)

Compal:

CH7465-LG (Arris TG2492LG / Virgin Media Hub 3) CH7466

Hitron:

CDA Series: CDA-32372 CDA-3-35
CDE Series: CDE-32372
CGN3 Series: CGN3, CGN3ACR,CGN3AMF, CGN3AMR, CGN3ACSMR
CGNM Series: CGNM-2250 CGNM-3552
CGNDM Series:
CGNV Series: CGNV4

Linksys:

CM3016 CM3024 CG7500

Netgear:

CG4500 CG4500TM C6300 C6300BD (Telstra Gateway Max - Australia) CM700

Samsung:

Home Media Server

SMC:

D3G2408

 

[sfx2000]

are you gonna cover the intel puma6 fiasco going on? Its effecting just about every 32 channel modem out there, seems weird no mentions of it here

Check with the ISP's - Intel has come up with a fix...

http://www.fiercecable.com/cable/ar...-firmware-fix-for-puma-6-equipped-cable-modem

 

[DanH]

Check with the ISP's - Intel has come up with a fix...

http://www.fiercecable.com/cable/ar...-firmware-fix-for-puma-6-equipped-cable-modem

Go read the dslreport forums (the people who found the issue to begin with), that fix hasn't even remotely fixed the issues. Seems like it cant be fixed either.

http://www.dslreports.com/forum/r31...DP-Network-Latency-Issue-Discussion~start=510

http://www.dslreports.com/forum/r31...odem-Intel-Puma-6-MaxLinear-mistake~start=704


Trust me I have been on top of it since I have a 6190 sitting here useless replaced by a CM600....

 

[sfx2000]

We are off topic - but the Puma 6 mention is something anybody should note - once the mob gets into a frenzy, there's little chance of getting a good solution, as the product will always be suspect... even if the product is not at fault.

 

[sfx2000]

Go read the dslreport forums (the people who found the issue to begin with), that fix hasn't even remotely fixed the issues. Seems like it cant be fixed either.

Most likely it can - Silvermont's are pretty aggressive at power savings, and in certain tasks, they need some, for lack of a better word, help... what I've found on Linux and *BSD to reduce latency and jitter was to reduce the processor cstate scope - basically disabling their C6-BYT and C7-BYT states on low load, keeping the chip busy enough... this is a brutal approach, less elegant than jumping into the kernel code, but hey, it works..

[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.4.0-53-generic.efi.signed root=UUID=<snip> ro intel_idle.max_cstate=1
[    0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.4.0-53-generic.efi.signed root=UUID=<snip> ro intel_idle.max_cstat=1
[    1.226170] intel_idle: max_cstate 1 reached

I'm sure that there is something similar in eCOS, which many devices like this run...

 

[sfx2000]

And the impact of the change below... and this is pretty similar to what the Puma 6 is doing in the SB6190...

 

[DanH]

Most likely it can - Silvermont's are pretty aggressive at power savings, and in certain tasks, they need some, for lack of a better word, help... what I've found on Linux and *BSD to reduce latency and jitter was to reduce the processor cstate scope - basically disabling their C6-BYT and C7-BYT states on low load, keeping the chip busy enough... this is a brutal approach, less elegant than jumping into the kernel code, but hey, it works..

[    0.000000] Command line: BOOT_IMAGE=/boot/vmlinuz-4.4.0-53-generic.efi.signed root=UUID=<snip> ro intel_idle.max_cstate=1
[    0.000000] Kernel command line: BOOT_IMAGE=/boot/vmlinuz-4.4.0-53-generic.efi.signed root=UUID=<snip> ro intel_idle.max_cstat=1
[    1.226170] intel_idle: max_cstate 1 reached

I'm sure that there is something similar in eCOS, which many devices like this run...

Not sure why under full load they would go into a idle state. Seems to me it is more of the chip cant handle what it is doing in hardware, and so its choking ~ every 20 seconds dropping packets and just stalling out.

 

[sfx2000]

So Puma 6 could be Bonnell or Saltwell, which would be the classic Atom, or the Silvermont (intel's putting that core in everything these days) - but the intel_idle.c code for both of those cores is similar... in an embedded application like a cable modem, there's little need to go into C-6 state at all...

 

[sfx2000]

Not sure why under full load they would go into a idle state. Seems to me it is more of the chip cant handle what it is doing in hardware, and so its choking ~ every 20 seconds dropping packets and just stalling out.

Might be under load on the data plane, but not necessarily on the control plane... but the timing domain changes can impact other items if not careful... without knowing more details under the hood, my best bet is the idle driver.

(FWIW - this is likely what other chip vendors don't do much frequency scaling on communications processors, just for this reason)

 

[DanH]

well hopefully it is as simple a fix as you suggest. Right now mine is in a box in the garage as I would feel bad even selling it to someone. (ironically arris, netgear et al don't feel bad about continuing to sell them, which tells me about how much they care about fixing it!)

 

[sfx2000]

Anyways, I knew there were some performance concerns with the 6190, that why I replaced my dead 6141 with a 6183...

But even when Intel's change rolls out - any little glitch, whether it is the modem, the ISP's network, or something on the LAN, the 6190 will always get blamed moving forward for those that suffered through the pain of early adoption...

 

[Blinkyz]

I just upgraded my internet to 120 \ 20 (videotron) and they installed their modem, Hitron CDA-RES.
http://www.vmedia.ca/support/documents/Hitron-CDA-MODEM-UI-QUICK-GUIDE.pdf.
I have a doubt
My ISP cant answer me if it is the Intel Puma 6 inside.After 2 hours of researchs on the WEB, I find nothing that speaks of the CPU inside.
I dont see this model in the list in post #1,but i see some hitron
Someone would have this information? Or how to get it.I cant access the WeB UI, ISP does not allow it.
I have send 2 emails to Hitron with no answers.

*Since 2 weeks I have this modem, and there seems to be no problem so far
Thanx