neyshule at gmail
Jan 21, 2012, 10:13 AM
Post #3 of 3
(273 views)
Permalink
|
*Much thanks for your reply, Luca:*
*The question is pfring_recv function is still the same. Watermark is just
added to different applications, like pfcount, I saw watermark here, but
the receiving mechanism is the same, isn't it?
*
2012/1/21 Luca Deri <deri [at] ntop>
> Eugene
> this is old stuff. In the current PF_RING we use a different approach. We
> implement the concept of watermark (i.e. a minimum amount of packets that
> poll() will wait before waking up the app) so that when the app is awaken
> it has a few packets to process and thus avoids this constant
> poll/sleep/poll mechanism
>
> Luca
>
> On Jan 19, 2012, at 4:17 AM, shule ney wrote:
>
> > Hi Luca:
> > I have a small question about your paper "Beyond Device Polling":
> > In the last month the real-time patch issue has been solved using an
> adaptive poll
> > algorithm. In other words, whenever there are no packets to process, the
> library sleeps
> > for a limited amount of time (usually a few nano-seconds, because
> otherwise the system
> > will loose packets as the userspace application will not fetch packets
> from the kernel)
> > before poll() is called. If, after the sleep, there are still no packets
> available, poll() is
> > called, otherwise packets are processed immediately. The sleep time is
> adapted
> > according to the incoming packet rate: the more incoming packets
> means shorter (or
> > zero) sleep time. Thanks to this trick, poll() is called very seldom
> hence avoiding the
> > need to improve system calls performance with third party patches.
> >
> > In this paragraph, you mentioned sleep, so where should sleep be put and
> how to realize this nano scale sleep?
> >
> >
> >
> > Best
> > Eugene
> > _______________________________________________
> > Ntop-misc mailing list
> > Ntop-misc [at] listgateway
> > http://listgateway.unipi.it/mailman/listinfo/ntop-misc
>
> ---
>
> "Debugging is twice as hard as writing the code in the first place.
> Therefore, if you write the code as cleverly as possible, you are, by
> definition, not smart enough to debug it. - Brian W. Kernighan
>
> _______________________________________________
> Ntop-misc mailing list
> Ntop-misc [at] listgateway
> http://listgateway.unipi.it/mailman/listinfo/ntop-misc
>
|
