Oliver Endriss wrote: > Robert Schedel wrote: >> Robert Schedel wrote: >> >>> Is the 250ms timeout an approved limit? Decreasing it would push the >>> load further down. Probably it still has to cover slow CAMs as well as a >>> stressed PCI bus. Unfortunately, without CAM/CI I cannot make any >>> statements myself. >> Just got another idea to improve the code: Function >> "saa7146_wait_for_debi_done_sleep" could be reworked to use what is >> known as "truncated binary exponential backoff" algorithm. IOW, on each >> sleep duplicate the period from 1ms until a fixed maximum, e.g. 32ms. >> This way polling ends fast for those users with fast bus/CAM, and those >> requiring 200ms due to slow bus/CAM should not worry about e.g. 216ms >> response time. >> >> My first tests look promising (load goes down to 0). However, is not the >> simple BEB algorithm already patented? > > Load should go down to 0 if the sleep call does not busy-wait. > > Please test whether the attached code fixes the problem. > Btw, I will not claim a patent for that. :D OK, I just took the time to make a more reliable test series (because load measurements varied). All nonessential system processes and modules were terminated before the test. Basically, only the login shell and the budget_av module were left. 1 minute uptime was used for measurements. Kernel: Linux 2.6.25 HW: Athlon 64 X2 3800+, Satelco EasyWatch DVB-C (as before) 1. Original module budget_av is loaded: Load: ~0,6-0,8 2. Module + Patch "saa7146_sleep.diff" (1ms/10ms polling intervals in debi_done function): Load: ~0,6-0,8 (same as in 1., no difference visible) 3. Module + Patch "incr-empty-ca-slot-poll-2.6.24.4.patch" (5s polling timer on slot state EMPTY): Load: Decays to 0,02, but after about 105s always a spike to 0,10, then again decays to 0,02, and so on 4. Module + Patch "incr-empty-ca-slot-poll" + "saa7146_sleep.diff": Same as 3. 5. Module + Patch "incr-empty-ca-slot-poll" + "binary exponential backoff": Same as 3. 6. Module budget_av is unloaded: Load constantly stays at 0, no spikes Bottomline for me: - Increasing the poll timer from 100ms, e.g. to 5s, makes sense. Changing the polling intervals in the debi_done function, however, makes no difference (unlike my previous assumption which was caused by the ugly variations). - There seems to be a spike in the CPU load, each ~105s, but only when budget_av is loaded. I cannot explain it (maybe some frontend background functions), but it is no issue for me. Regards, Robert _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
