[dpdk-dev] DPDK testpmd, Virtual Disk IO limitation
Bruce Richardson
bruce.richardson at intel.com
Wed Mar 25 16:01:57 CET 2015
On Wed, Mar 25, 2015 at 10:06:48PM +0800, Cheng Kevin wrote:
> Hi all,
>
> I am a beginner of DPDK. Recently, i am interest in DPDK vHost app -
> testpmd.
>
> And i have been tracing on testpmd.c and iofwd.c for a while.
>
> Also add some code inside iofwd.c for storing the payload of packets.
>
> Everything goes fine, and the performance is great as expected.
>
> But when i use fwrite to store the payload into a file,
>
> the performance decrease from 800mbps to 3mbps (input stream is 1 Gbps).
>
> Is is caused by the limitation of Virtual Disk IO? How can i solve it?
>
> I have tried to search the answer, some people say "pthread" might solve
> the problem.
>
> Can someone give me some hint, i really appreciate for your help.
>
>
> Best Regard,
>
> Kevin Cheng
Two general issues you will hit writing to disk:
1) IO, including disk IO, is slow
2) System calls are slow.
You are probably hitting both bottlenecks.
/Bruce
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