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From: "Patel, Rashmin N" <rashmin.n.patel@intel.com>
To: Matthew Hall <mhall@mhcomputing.net>, "Vass, Sandor (Nokia - HU/Budapest)"
 <sandor.vass@nokia.com>
Thread-Topic: [dpdk-dev] VMXNET3 on vmware, ping delay
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Date: Thu, 25 Jun 2015 20:56:16 +0000
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Cc: "dev@dpdk.org" <dev@dpdk.org>
Subject: Re: [dpdk-dev] VMXNET3 on vmware, ping delay
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For tuning ESXi and vSwitch for latency sensitive workloads, I remember the=
 following paper published by VMware: https://www.vmware.com/files/pdf/tech=
paper/VMW-Tuning-Latency-Sensitive-Workloads.pdf that you can try out.

The overall latency in setup (vmware and dpdk-vm using vmxnet3) remains in =
vmware-native-driver/vmkernel/vmxnet3-backend/vmx-emulation threads in ESXi=
. So you can better tune ESXi (as explained in the above white paper) and/o=
r make sure that these important threads are not starving to improve latenc=
y and throughput in some cases of this setup.

Thanks,
Rashmin

-----Original Message-----
From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Matthew Hall
Sent: Thursday, June 25, 2015 8:19 AM
To: Vass, Sandor (Nokia - HU/Budapest)
Cc: dev@dpdk.org
Subject: Re: [dpdk-dev] VMXNET3 on vmware, ping delay

On Thu, Jun 25, 2015 at 09:14:53AM +0000, Vass, Sandor (Nokia - HU/Budapest=
) wrote:
> According to my understanding each packet should go through BR as fast=20
> as possible, but it seems that the rte_eth_rx_burst retrieves packets=20
> only when there are at least 2 packets on the RX queue of the NIC. At=20
> least most of the times as there are cases (rarely - according to my=20
> console log) when it can retrieve 1 packet also and sometimes only 3=20
> packets can be retrieved...

By default DPDK is optimized for throughput not latency. Try a test with he=
avier traffic.

There is also some work going on now for DPDK interrupt-driven mode, which =
will work more like traditional Ethernet drivers instead of polling mode Et=
hernet drivers.

Though I'm not an expert on it, there is also a series of ways to optimize =
for latency, which hopefully some others could discuss... or maybe search t=
he archives / web site / Intel tuning documentation.

Matthew.