Re: Only ~85MiB/s (e1000e/write) to ~310MiB/s RAID-0 on ATOM board?

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On Sun, 16 Jan 2011, Ian E. Morgan wrote:

Justin,

I have two Supermicro 5015a-EHF-D525's. They use the same Intel 82574L
NICs as your slightly older board.
I asked myself the same questions as you just recently, and my
research into multi-queue NIC support led to:

Receive Packet Steering

Take a look at the output of NET_TX and NET_RX in /proc/softirq.
The interrupts were not balanced across the cpus until I did:

echo f > /sys/devices/pci0000:00/0000:00:1c.1/0000:02:00.0/net/eth0/queues/rx-0/rps_cpus
("f" being a bitmask of cpus)

Then the interrupts started balancing across all cpus.
I haven't had a chance to try this in a high throughput transfer
situation yet, as I just happened to look into this last night.

Hope it leads you down the right path, and please let me know if it
does or doesn't help, or any other solutions you've found or come up
with.

--
Ian Morgan


Hi Ian,

Thanks for the response & suggestion!

Tried it on kernel 2.6.37:

Made sure it was enabled:
# grep RPS .config
CONFIG_RPS=y

Only achieved 79.98M/s on > 4 GB of data via FTP (downloading), does not
appear to change much.

# cat /sys/class/net/eth1/queues/rx-0/rps_cpus
0

# echo f > /sys/class/net/eth1/queues/rx-0/rps_cpus
# cat /sys/class/net/eth1/queues/rx-0/rps_cpus
f
#

# cat /proc/softirqs
                    CPU0       CPU1       CPU2       CPU3
          HI:          0          0          0          0
       TIMER:     508490     507869     508325     508253
      NET_TX:      22933      24274      23800      22124
      NET_RX:      94412     218903      93273      95787
       BLOCK:      63945      22646      21324       8084
BLOCK_IOPOLL:          0          0          0          0
     TASKLET:          8          4          2          5
       SCHED:     244572     218617     262071     242491
     HRTIMER:          0          0          0          0
         RCU:      52859      53519      53715      55199


What speed(s) do you achieve with the D525s?

If anyone finds out why these boards cannot achieve > 90-100MiB/s to disk,
I'd be curious to know why, thanks.

Justin.

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