Hello Andreas,
while looking through the osmo-pcu code to figure out why some connections stall we had some problems making sense of the elapsed time calculations in gprs_rlcmac_meas.cpp.
Could you confirm/deny my assumptions about it or explain the idea behind it?
gettimeofday(&now_tv, NULL); elapsed = ((now_tv.tv_sec - loss_tv->tv_sec) << 7)
- ((now_tv.tv_usec - loss_tv->tv_usec) << 7) / 1000000;
I assume here you're calculating the duration of the measurement period so far and since you want to have sub-second accuracy you multiply everything with 128. Why 128? Is it becasue it simplifies the throughput calculation? (tbf->meas.dl_bw_octets/elapsed in gprs_rlcmac_dl_bw())
if (elapsed < 128) return 0;
Is the intention here that the duration of the measurements is supposed to be one second? So every second these measurements are printed out and reset?
Regards Daniel Willmann
Daniel Willmann wrote:
gettimeofday(&now_tv, NULL); elapsed = ((now_tv.tv_sec - loss_tv->tv_sec) << 7)
- ((now_tv.tv_usec - loss_tv->tv_usec) << 7) / 1000000;
I assume here you're calculating the duration of the measurement period so far and since you want to have sub-second accuracy you multiply everything with 128. Why 128? Is it becasue it simplifies the throughput calculation? (tbf->meas.dl_bw_octets/elapsed in gprs_rlcmac_dl_bw())
hi daniel,
yes. first i wanted something more accurate than one second, so i multiplied the elapsed time with 128. 128 bytes are 1024 bits, so it simplifies the calculation for kbits/s.
if (elapsed < 128) return 0;
Is the intention here that the duration of the measurements is supposed to be one second? So every second these measurements are printed out and reset?
after every transmitted downlink frame the gprs_rlcmac_dl_bw() function is called. if at least one second is elapsed, the throughput of the time that has been elapsed is printed out. it is just a simple solution without the requirement for a timer for each TBF.
regards,
andreas
osmocom-net-gprs@lists.osmocom.org
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Andreas Eversberg -
Daniel Willmann