Thanks for the answers. So the only way to make handlep->timeout>=0, is by setting the file-descriptor to "blocking" (nonblock=0) according to the logic in function pcap_setnonblock_mmap() and this is something that we would like to avoid. Therefore, we do the polling (non-blocking) in the application that uses pcap/pf_ring. The problem we have is with low-traffic network. According to the logic in function copy_data_to_ring(), as long as the queue didn't reach the "poll_num_pkts_watermark" threshold (in our case 128 packets), the poll() (in userspace) won't be called (since wake_up_interruptible(..) is not called), which means that we have packets that are stuck in the ring till the queue reaches the watermark.
I wonder if you see any rationale in improving the pf_ring kernel module code, to call wake_up_interruptible() (in order to flush the queue) if some "timeout" passed and the queue is not empty (but still didn't reach the watermark). Amir On Thu, Apr 26, 2018 at 6:00 PM, Alfredo Cardigliano <cardigli...@ntop.org> wrote: > > > On 26 Apr 2018, at 15:34, Amir Kaduri <akadur...@gmail.com> wrote: > > Hi Alfredo, > > My code is based on libpcap, while pfring's userland examples use pfring > APIs directly, therefore things are a bit harder for me. > > Short clarification about a related code-line: > Please look at the following line: https://github.com/ntop/ > PF_RING/blob/dev/userland/libpcap-1.8.1/pcap-linux.c#L1875 > > (1) If I understand it correctly, if wait_for_incoming_packet is true, > then pfring_poll() should be called. > Don't you want wait_for_incoming_packet to be true in case > pf_ring_active_poll is true? > > > “active” means spinning, thus poll should not be used in that case. > > Currently, its the opposite (i.e. if pf_ring_active_poll is true, > wait_for_incoming_packet will be false thus pfring_poll() won't be > called). > > > This seems to be correct > > > (2) If the code is ok, then the only way for me to make > wait_for_incoming_packet true (for pfring_poll() to be called) is by > making handlep->timeout >= 0. > Correct? > > > Correct > > Alfredo > > > Thanks, > Amir > > On Mon, Apr 9, 2018 at 10:51 AM, Alfredo Cardigliano <cardigli...@ntop.org > > wrote: > >> Hi Amir >> if I understand correctly, pfcount_multichannel is working, while in your >> application >> it seems that poll does not honor the timeout, if this is the case it >> seems the problem >> is not in the kernel module, I think you should look for differences >> between the two applications.. >> >> Alfredo >> >> On 9 Apr 2018, at 07:20, Amir Kaduri <akadur...@gmail.com> wrote: >> >> Hi Alfredo, >> >> I'm back to investigate/debug this issue in my environment, and maybe >> you'll manage to save me some time: >> >> When I use the example program "pfcount_multichannel", poll-duration >> works for me as expected: >> For watermark=128, poll-duration=1000, even if less than 128 packets >> received, I get them in pfcount_multichannel. >> >> On the other hand, in my other program (which is a complex one), the >> userspace application gets the packets only after 128 packets >> aggregated by the ring, regardless the polling rate (which is done always >> using 50ms timeout). >> >> Maybe you can figure out what can "hold" the packets in the ring and >> forward them to userspace only when the watermark threshold passes? >> Maybe something is missing during initialization? >> (for simplicity I'm not using rehash, and not using any filters). >> >> Thanks >> >> On Tue, Oct 31, 2017 at 6:32 PM, Alfredo Cardigliano < >> cardigli...@ntop.org> wrote: >> >>> Hi Amir >>> that's correct, however for some reason it seems it is not the case in >>> your tests. >>> >>> Alfredo >>> >>> On 31 Oct 2017, at 12:08, Amir Kaduri <akadur...@gmail.com> wrote: >>> >>> Thanks. tot_insert apparently works ok. >>> >>> Regarding function copy_data_to_ring(): >>> At the end of it there is the statement: >>> if(num_queued_pkts(pfr) >= pfr->poll_num_pkts_watermark) >>> wake_up_interruptible(&pfr->ring_slots_waitqueue); >>> >>> Since watermark is set to 128, and I send <128 packets, this causes them >>> to wait in kernel queue. >>> But since poll_duration is set to 1 (1 millisecond I assume), I expect >>> the condition to check this also (meaning, there are packets in queue but 1 >>> millisecond passed and they weren't read), >>> the wake_up_interruptible should also be called. No? >>> >>> Thanks, >>> Amir >>> >>> >>> On Tue, Oct 31, 2017 at 10:20 AM, Alfredo Cardigliano < >>> cardigli...@ntop.org> wrote: >>> >>>> >>>> >>>> On 31 Oct 2017, at 08:42, Amir Kaduri <akadur...@gmail.com> wrote: >>>> >>>> Hi Alfredo, >>>> >>>> I'm trying to debug the issue, and I have a question about the code, to >>>> make sure that there is no problem there: >>>> Specifically, I'm referring to the function "pfring_mod_recv": >>>> In order that the line that refers to poll_duration ("pfring_poll(ring, >>>> ring->poll_duration)") will be reached, there are 2 conditions that should >>>> occur: >>>> 1. pfring_there_is_pkt_available(ring) should return false (otherwise, >>>> the function returns at the end of the condition). >>>> 2. wait_for_incoming_packet should be set to true. >>>> Currently, I'm referring to the first one: >>>> In order that the macro pfring_there_is_pkt_available(ring) will >>>> return false, ring->slots_info->tot_insert should be equal to >>>> ring->slots_info->tot_read. >>>> What I see in my tests that they don't get equal. I always see that >>>> tot_insert>tot_read, and sometimes they get eual when tot_read++ is called >>>> but it happens inside the condition, so the "pfring_mod_recv" returns with >>>> 1. >>>> >>>> >>>> It seems to be correct. The kernel module inserts packets into the ring >>>> increasing tot_insert, the userspace library reads packets from the ring >>>> increasing tot_read. This means that if tot_insert == tot_read there is no >>>> packet to read. If there is a bug, it should be in the kernel module that >>>> is somehow not adding packets to the ring (thus not updating tot_insert). >>>> >>>> Alfredo >>>> >>>> I remind that I set the watermark to be high, in order to see the >>>> poll_duration takes effect. >>>> >>>> Could you please approve that you don't see any problem in the code? >>>> >>>> Thanks, >>>> Amir >>>> >>>> >>>> On Thu, Oct 26, 2017 at 12:22 PM, Alfredo Cardigliano < >>>> cardigli...@ntop.org> wrote: >>>> >>>>> Hi Amir >>>>> yes, that’s the way it should work, if this is not the case, some >>>>> debugging is needed to identify the problem >>>>> >>>>> Alfredo >>>>> >>>>> On 26 Oct 2017, at 10:14, Amir Kaduri <akadur...@gmail.com> wrote: >>>>> >>>>> Basically, the functionality that I would like to have is even if less >>>>> than poll-watermark-threshold (default: 128) packets arrives the socket, >>>>> they will be forwarded to userland if 1 millisecond has passed. >>>>> How can I gain this? Isn't it by using pfring_set_poll_duration()? >>>>> >>>>> Alfredo, could you please clarify? >>>>> >>>>> Thanks, >>>>> Amir >>>>> >>>>> On Wed, Oct 18, 2017 at 8:48 PM, Amir Kaduri <akadur...@gmail.com> >>>>> wrote: >>>>> >>>>>> Hi, >>>>>> >>>>>> I'm using pf_ring 6.6.0 (no ZC) on CentOS 7, on 10G interfaces (ixgbe >>>>>> drivers). >>>>>> As far as I understand the relation between poll-watermark and >>>>>> poll-duration, packets will be queued untill one of comes first: or >>>>>> passing >>>>>> the poll-watermark packets threshold, or a poll-duration milliseconds has >>>>>> passed. >>>>>> I set poll-watermark to the maximum (4096) >>>>>> (using pfring_set_poll_watermark()) and set poll-duration to the >>>>>> minimum (1) (using pfring_set_poll_duration()). >>>>>> I've sent 400 packets to the socket. I see that they are received by >>>>>> the NIC, but they didn't pass to userland. Only when passing 500 >>>>>> packets, a >>>>>> chunk of them passed to userland. >>>>>> I don't quite understand the behavior: since poll-duration is 1 >>>>>> (millisecond I assume), I've expected all the packets to pass to userland >>>>>> immediately, even though poll-watermark is much higher. >>>>>> >>>>>> Can anyone shed some light on the above? >>>>>> >>>>>> Thanks, >>>>>> Amir >>>>>> >>>>> >>>>> _______________________________________________ >>>>> Ntop-misc mailing list >>>>> Ntop-misc@listgateway.unipi.it >>>>> http://listgateway.unipi.it/mailman/listinfo/ntop-misc >>>>> >>>>> >>>>> >>>>> _______________________________________________ >>>>> Ntop-misc mailing list >>>>> Ntop-misc@listgateway.unipi.it >>>>> http://listgateway.unipi.it/mailman/listinfo/ntop-misc >>>>> >>>> >>>> _______________________________________________ >>>> Ntop-misc mailing list >>>> Ntop-misc@listgateway.unipi.it >>>> http://listgateway.unipi.it/mailman/listinfo/ntop-misc >>>> >>>> >>>> >>>> _______________________________________________ >>>> Ntop-misc mailing list >>>> Ntop-misc@listgateway.unipi.it >>>> http://listgateway.unipi.it/mailman/listinfo/ntop-misc >>>> >>> >>> _______________________________________________ >>> Ntop-misc mailing list >>> Ntop-misc@listgateway.unipi.it >>> http://listgateway.unipi.it/mailman/listinfo/ntop-misc >>> >>> >>> _______________________________________________ >>> Ntop-misc mailing list >>> Ntop-misc@listgateway.unipi.it >>> http://listgateway.unipi.it/mailman/listinfo/ntop-misc >>> >> >> _______________________________________________ >> Ntop-misc mailing list >> Ntop-misc@listgateway.unipi.it >> http://listgateway.unipi.it/mailman/listinfo/ntop-misc >> >> >> >> _______________________________________________ >> Ntop-misc mailing list >> Ntop-misc@listgateway.unipi.it >> http://listgateway.unipi.it/mailman/listinfo/ntop-misc >> > > _______________________________________________ > Ntop-misc mailing list > Ntop-misc@listgateway.unipi.it > http://listgateway.unipi.it/mailman/listinfo/ntop-misc > > > > _______________________________________________ > Ntop-misc mailing list > Ntop-misc@listgateway.unipi.it > http://listgateway.unipi.it/mailman/listinfo/ntop-misc >
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