Red Hat Bugzilla – Bug 146999
interval timer 1ms late
Last modified: 2015-01-04 17:16:29 EST
From Bugzilla Helper: User-Agent: Mozilla/5.0 (X11; U; Linux i686; en-US; rv:1.7.3) Gecko/20041020 Epiphany/1.4.4 Description of problem: When using setitimer(ITIMER_REAL, &itv, 0) to get periodic interrupts for N milliseconds (N*1000 microseconds), the actual interval is N+1 milliseconds. For example, with an interval set to exactly 1000 microseconds, the actual interval obtained is 2000 microseconds. If the interval is set to 999 microseconds, the interval obtained is 1000 microseconds. If the interval is set to 2000 microseconds, the actual interval obtained is 3000 microseconds... Version-Release number of selected component (if applicable): kernel-2.6.10-1.741_FC3 How reproducible: Always Steps to Reproduce: 1. Write a program wich uses setitimer(ITIMER_REAL, &itv, 0) to set an interval timer of N microseconds, and compute the average actual interval with gettimeofday. 2. run the program with N set to 1000 microseconds 3. run the program with N set to 999 microsedonds Actual Results: In the first case tha average interval is around 2 ms. In the second, it is around 1 ms. Expected Results: In both cases, the delay should be around 1 ms. Additional info: Processors : Athlon XP 1800+, Pentium IV 3.5GHz, Xeon 2.7 GHz.
An update has been released for Fedora Core 3 (kernel-2.6.12-1.1372_FC3) which may contain a fix for your problem. Please update to this new kernel, and report whether or not it fixes your problem. If you have updated to Fedora Core 4 since this bug was opened, and the problem still occurs with the latest updates for that release, please change the version field of this bug to 'fc4'. Thank you.
This bug has been automatically closed as part of a mass update. It had been in NEEDINFO state since July 2005. If this bug still exists in current errata kernels, please reopen this bug. There are a large number of inactive bugs in the database, and this is the only way to purge them. Thank you.