Mr. Bruce Richardson Yes, you are right. This really bother me.
Is there any way to get rid of system call? Maybe some DPDK threading API? Maybe i should use a extra nic card for posting the data out through internet, instead of writing on the disk - ex. fwrite. Or you have some better advises?? Thanks Kevin 2015-03-25 23:01 GMT+08:00 Bruce Richardson <bruce.richardson at intel.com>: > 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 >
