[ovs-dev] [RFC 0/4] Status of mmap upcall work

[Thomas Graf]

On 05/23/14 at 01:15am, Thomas Graf wrote:
> Test: * Avg pps as reported by pktgen for a single pktgen thread
>       * qemu, vcpu=2, mem=2GB, megaflows disabled
> 
>                  Orig [0]  ZC [1]    mmap [2]  shared-ofpbuf [3]
>  64B (linear)    624K      564K      962K      900K
> 1.5K (linear)    612K      629K      800K      891K
>   9K (linear)    476K      474K      508K      513K
>   9K (4 frags)   365K      411K      503K      631K
> 
[...]
> 		
> Numbers on ring buffer size:
>   ring-size:  512K    1M    2M    4M
>         pps:  596K  914K  926K  900K

Another option is to reduce the max frame size from 16K to 4K or even
2K (translating to a ring size of 256KB respectively 128KB) and handle
messages >4K through a regular recvmsg() again. Tests indicate that
the performance for these exceeding messages is on the same level as
they are now.

I would personally consider this option if we can't come up with a
solution to the fairness issue using shared rings.