Increasing CPU Efficiency

xerox123 · January 20, 2026, 6:04pm

Hi everyone, I have a router with a MediaTek MT7621 CPU and I've configured the IRQ settings like this, and my internet is a bit more stable. Do you have any suggestions on how to make the CPU work more efficiently with these IRQ settings, or can I get the best performance with these settings?

Hostname	OpenWrt
Model	Xiaomi Mi Router 4A Gigabit Edition
Architecture	MediaTek MT7621 ver:1 eco:3
Target Platform	ramips/mt7621

root@OpenWrt:~# cat /proc/interrupts
           CPU0       CPU1       CPU2       CPU3       
  8:     186134     220702     374616     402828  MIPS GIC Local   1  timer
  9:     679050          0          0          0  MIPS GIC  63  IPI call
 10:          0     140508          0          0  MIPS GIC  64  IPI call
 11:          0          0    1383897          0  MIPS GIC  65  IPI call
 12:          0          0          0     286261  MIPS GIC  66  IPI call
 13:       9057          0          0          0  MIPS GIC  67  IPI resched
 14:          0       1534          0          0  MIPS GIC  68  IPI resched
 15:          0          0       5580          0  MIPS GIC  69  IPI resched
 16:          0          0          0       1540  MIPS GIC  70  IPI resched
 17:          0          0          0          0  MIPS GIC  19  1e000600.gpio-bank0, 1e000600.gpio-bank1, 1e000600.gpio-bank2
 18:         12          0          0          0  MIPS GIC  33  ttyS0
 19:        345     595779          0          0  MIPS GIC  10  1e100000.ethernet
 20:          0          0          0          0  MIPS GIC  30  mt7530
 23:          0          0          0          0    mt7530   2  mt7530-0:02
 24:          0          0          0          0    mt7530   3  mt7530-0:03
 25:          0          0          0          0  mt7621-gpio  18  keys
 26:          0          0          0          0  MIPS GIC  26  1e004000.crypto
 27:         22          0          0          0  MIPS GIC  31  mt7603e
 28:       1165    1435720          0          0  MIPS GIC  11  mt76x2e
ERR:       1103
root@OpenWrt:~# uptime
 21:01:36 up  2:18,  load average: 0.05, 0.05, 0.00
root@OpenWrt:~#

frollic · January 20, 2026, 6:06pm

As you've been told before, get beefier hw.

brada4 · January 20, 2026, 6:14pm

First is that 1st and 2nd CPU pairs are actually sharing 2 cores. And even then you run both network interrupts on same core. Could help balancing either ethernet or wifi to cores 2/3

Please connect to your OpenWrt device using ssh and copy the output of the following commands and post it here using the "Preformatted text </> " button (red circle; this works best in the 'Markdown' composer view in the blue oval):

Remember to redact passwords, VPN keys, MAC addresses and any public IP addresses you may have:

ubus call system board

You can seek some fw4 patches to reduce CPU/memory usage for packet forwarding, but dont expect wonders.

xerox123 · January 20, 2026, 7:07pm

root@OpenWrt:~# cat /proc/interrupts
           CPU0       CPU1       CPU2       CPU3       
  8:     148572      79347      91102      85988  MIPS GIC Local   1  timer
  9:     527754          0          0          0  MIPS GIC  63  IPI call
 10:          0      55873          0          0  MIPS GIC  64  IPI call
 11:          0          0     143816          0  MIPS GIC  65  IPI call
 12:          0          0          0     120931  MIPS GIC  66  IPI call
 13:       6141          0          0          0  MIPS GIC  67  IPI resched
 14:          0       1793          0          0  MIPS GIC  68  IPI resched
 15:          0          0      32604          0  MIPS GIC  69  IPI resched
 16:          0          0          0       1512  MIPS GIC  70  IPI resched
 17:          0          0          0          0  MIPS GIC  19  1e000600.gpio-bank0, 1e000600.gpio-bank1, 1e000600.gpio-bank2
 18:         12          0          0          0  MIPS GIC  33  ttyS0
 19:         67     506170          0          0  MIPS GIC  10  1e100000.ethernet
 20:          0          0          0          0  MIPS GIC  30  mt7530
 23:          0          0          0          0    mt7530   2  mt7530-0:02
 24:          0          0          0          0    mt7530   3  mt7530-0:03
 25:          0          0          0          0  mt7621-gpio  18  keys
 26:          0          0          0          0  MIPS GIC  26  1e004000.crypto
 27:         23          0          0          0  MIPS GIC  31  mt7603e
 28:        217          0     832750          0  MIPS GIC  11  mt76x2e
ERR:        413
root@OpenWrt:~#

I did as you said, and now it's much more stable. Did I do it right?

I've currently distributed network operations to shortcut CPU 1 (number 19), set Wi-Fi to CPU 2, and the small values on CPU 0 are boot-time values; they're not working.

brada4 · January 20, 2026, 7:22pm

Normally that is done by irqbalance but did not work on ramips (last time I checked)...
You can save 1/3 iifname matches per forwarded packet by https://github.com/openwrt/firewall4/pull/27
And replace one payload examination with integer comparison https://github.com/openwrt/firewall4/pull/31
Those are per-packet slack processing....

foxtokyo · January 21, 2026, 12:24am

Can this particular router do sqm?

Which router do you recommend for average users

brada4 · January 21, 2026, 12:29am

Depends on speed, rockchip or filogic will sqm gigabit if that is the question. Ask in a new thread if you need more exotic config.
7621 will do ok for 100-300Mbps

Mpilon · January 21, 2026, 1:41am

Dumb question - if I'm reading this correctly cpu 1 & 2 share 1 core, 2 & 3 the other. Is this correct?

Thanks!

foxtokyo · January 21, 2026, 2:06am

Thank you

One more question:

Should I enable packet steering for sqm on this router? If so, should I simply select ‘enabled’ or ‘enabled (all cpu cores)’

Should I touch Steering flows (RPS)? It's shown as ‘Standard none’

moeller0 · January 21, 2026, 5:52am

That tends to help. On dual core routers selecting "all CPUs" is essential, with SMT I assume as well, but am not 100% sure as I lack an openWrt device with SMT.

moeller0 · January 21, 2026, 6:01am

I must say I would be (positively) surprised if the upper end of that estimate was the case... 880 MHz with ancient MIPS cores

konus · January 21, 2026, 10:38am

I've had a look at the links and the 1st one consists of just random AI stuff. The 2nd one is OpenWrt related and looks like someone's personal 'optimisation'. I would recommend people to read through any scripts and understand what they do before running them on your router.

brada4 · January 21, 2026, 1:25pm

2nd one also has broccolis in output and network part does nothing (sets fw mark on supposedly lan on x86 then that is consumed by noqueue at best)

iamyangyi · January 25, 2026, 12:29am

Could you teach me how to do this on OpenWRT? Thanks. I keep the helper modules disabled in daily use.

inet fw4 prerouting

[ meta load iifname => reg 1 ]

[ cmp eq reg 1 0x6c2d7262 0x00006e61 0x00000000 0x00000000 ]

[ immediate reg 0 jump -> helper_lan ]

userdata = { \x00-!fw4: Handle lan IPv4/IPv6 helper assignment\x00 }

brada4 · January 25, 2026, 6:59am

-d netlink