Re: [PATCH v4 net-next 2/4] net: convert low latency sockets to sched_clock()

[Eliezer Tamir]

On 14/06/2013 06:12, Eric Dumazet wrote:
> On Fri, 2013-06-14 at 04:57 +0300, Eliezer Tamir wrote:
> > Use sched_clock() instead of get_cycles().
> > We can use sched_clock() because we don't care much about accuracy.
> > Remove the dependency on X86_TSC
> >
> > Signed-off-by: Eliezer Tamir <eliezer.tamir@xxxxxxxxxxxxxxx>
> > ---
>
> > -static inline bool can_poll_ll(cycles_t end_time)
> > +static inline bool can_poll_ll(u64 end_time)
> >   {
> > -	return !time_after((unsigned long)get_cycles(),
> > +	return !time_after((unsigned long)sched_clock(),
> >   			    (unsigned long)end_time);
> >   }
>
> I do not really understand why you bother to have 64bit wide values,
> and then use these "unsigned long" casts here.
>
> On 32bit arches, this will really limit to 2^31 ns range.
>
> You should instead either :
> - use time_after_64() or
> - explicitly limit sysctl_net_ll_poll range

OK
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