High CPU load when network is busy

[ignasio]

Hello,

forst time poster and user of free ESXi (novice with virtualization, decent understanding of networking and computer hardware), my problem seems simple yet I'm having a hard time finding out what is wrong. Anyway, I'm using a desktop computer for my small home server, light traffic, only few VMs.

Problem is that as soon as I start downloading/uploading, i.e. network gets busy, ESXi itself causes high CPU utilization. I mean ~1.7MB/s of traffic spikes CPU to 25%/200% (0.1%/200% on idle connection ~1KB/s):

I'm pretty sure it shouldn't cause such spikes with so little traffic. It's not pfSense's fault apparently, it runs great on ESXi, and they are adamant (pfSense's forums) that 1gbps traffic barely bends any CPU load graphs. I couldn't find help there. CPU jumps up too when transfering files between Ubuntu 12.04 VM and my Desktop PC with Windows 7 (without pfSense interaction).

pfSense on said load (2.0.2 32bit):

and ESXi (5.1) spikes:

On my network almost all VMs run on 1 vCPU 32bit Ubuntu Server 12.04 platforms, except a game server with 2 vCPUs on a 64bit, All E1000 adapter types:

I'm dredding to think that it might be my hardware/setup (mainly the non server-grade motherboard):

Athlon II X2 270 CPU

3 x Intel Gigabit Pro NICs

8GB Non-ECC Kingston RAM

Maxtor PATA Drive

Intel 520 SSD

AsRock N68-VS3 UCC Hybrid DDR2/DDR3 Motherboard (MCP61 NForce Sata/PATA Controller)

SSD was not recognized at first so I added it through "Host Cache Configuration" as LUN/Disk datastore and put all my VMs there, ESXi itself is on PATA drive. So I'm thinking that combination of non-HCL hardware, SSD and my ignorance is causing this, yet machine itself has never crashed, even though it's been running straight for 2 months. I only ask for help now because my ISP is upgrading my connection to fibre and I don't think my server will handle the 200 mbps traffic.

I would be grateful for any input.

[sflanders]

Hard to say. Typically network and CPU utilization are related so the higher the throughput the higher the CPU utilization. Server/Enterprise grade network cards allow offloading capabilities that attempt to mitigate these types of issues. With non supported, desktop grade hardware it may be hard to pin-point the issue. Not sure if it is an option for you or not, but perhaps look into a cheap desktop server the the Dell T110 line.

[ignasio]

Thanks for the reply. I though my problem would be apparent to experienced users, maybe something simple I missed. Time to upgrade my hardware then I guess.