On Apr 2, 2018, at 16:26, NeilBrown <ne...@suse.com> wrote: > On Mon, Apr 02 2018, Dilger, Andreas wrote: >> On Mar 30, 2018, at 13:02, James Simmons <jsimm...@infradead.org> wrote: >>>> This function simply multiplies by HZ and adds jiffies. >>>> This is simple enough to be opencoded, and doing so >>>> makes the code easier to read. >>>> >>>> Same for cfs_time_shift_64() >>> >>> Reviewed-by: James Simmons <jsimm...@infradead.org> >> >> Hmm, I thought we were trying to get rid of direct HZ usage in modules, >> because of tickless systems, and move to e.g. msecs_to_jiffies() or similar? > > Are we? I hadn't heard but I could easily have missed it. > Documentation/scheduler/completion.txt does say > > Timeouts are preferably calculated with > msecs_to_jiffies() or usecs_to_jiffies(). > > but is isn't clear what they are preferred to. Do you remember where > you heard? or have a reference?
I thought the goal was to avoid hard-coding the HZ value so that kernels could have variable clock rates in the future. Cheers, Andreas > $ git grep ' \* *HZ' |wc > 2244 15679 170016 > $ git grep msecs_to_jiffies | wc > 3301 13151 276725 > > so msecs_to_jiffies is slightly more popular than "* HZ" (even if you add > in "HZ *"). But that could just be a preference for using milliseconds > over using seconds. > > $ git grep msecs_to_jiffies | grep -c '[0-9]000' > 587 > > so there are only 587 places that msecs_to_jiffies is clearly used in > place of multiplying by HZ. > > If we were to pursue this, I would want to add secs_to_jiffies() to > include/linux/jiffies.h and use that. > > Thanks, > NeilBrown > _______________________________________________ > lustre-devel mailing list > lustre-de...@lists.lustre.org > http://lists.lustre.org/listinfo.cgi/lustre-devel-lustre.org Cheers, Andreas -- Andreas Dilger Lustre Principal Architect Intel Corporation
