Stauros Passas (stabat@xxxxxxxxxxxxxxxxxxx) wrote: > On Wed, 10 Aug 2005, Deepak Joshi wrote: > > >Hi all, > > > >I read that in order to get the current time by using > >do_gettimeofday( struct timeval *tv) function we need > >to disable the inturrepts because we can't access both > >fields of timeval struct tv_sec and tv_usec. Why is it > >so ? > Timing on linux kernel are base on Timer interrupts,that are > generated by system's timing hardware at regular intervlas, > according to the value of HZ. Every time a timer interrupt occurs, > jiffies incremented. I suppose that fields of timeval struct are > computed through jiffies, so it isn't safe to read them without > first disabling interrupts. It is a little more difficult than incremented jiffies in timer interrupt ;) Some corrections are applied. - http://lxr.linux.no/source/arch/i386/kernel/time.c - http://lxr.linux.no/source/kernel/timer.c#L867 Have a nice day, - Christophe (clucas@xxxxxxxxxxxxx) -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
