On Sat, Sep 17, 2016 at 12:09 PM, Cyrill Gorcunov <gorcunov@xxxxxxxxx> wrote: > On Sat, Sep 17, 2016 at 11:33:56AM +0300, Konstantin Khlebnikov wrote: >> > >> > do_just_once just isn't a good name for a global >> > rate limited mechanism that does something very >> > different than the name. >> > >> > Maybe allow_once_per_ratelimit or the like >> > >> > There could be an equivalent do_once >> > >> > https://lkml.org/lkml/2009/5/22/3 >> > >> >> What about this printk_reriodic() and pr_warn_once_per_minute()? >> >> It simply remembers next jiffies to print rather than using that >> complicated ratelimiting engine. > > +#define printk_periodic(period, fmt, ...) \ > +({ \ > + static unsigned long __print_next __read_mostly = INITIAL_JIFFIES; \ > + bool __do_print = time_after_eq(jiffies, __print_next); \ > + \ > + if (__do_print) { \ > + __print_next = jiffies + (period); \ > + printk(fmt, ##__VA_ARGS__); \ > + } \ > + unlikely(__do_print); \ > +}) > > Seems I don't understand the bottom unlikely... This is gcc extrension: https://gcc.gnu.org/onlinedocs/gcc/Statement-Exprs.html Here macro works as a function which returns bool After second though macro should update __print_next if it's too far if first warning happens too late here will long period of silence untill next jiffies overlap. something like #define printk_periodic(period, fmt, ...) ({ static unsigned long __print_next = INITIAL_JIFFIES; unsigned long __print_jiffies = jiffies; bool __do_print = time_after_eq(__print_jiffies, __print_next); if (__do_print) { __print_next = __print_jiffies + (period); printk(fmt, ##__VA_ARGS__); } else if (time_after(__print_next, __print_jiffies + (period)) __print_next = __print_jiffies + (period); unlikely(__do_print); }) -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>