Messages in this thread | | | Date | Wed, 28 Sep 2011 12:26:39 -0300 | From | Glauber Costa <> | Subject | Re: [RFD 4/9] Make total_forks per-cgroup |
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On 09/28/2011 05:13 AM, Martin Schwidefsky wrote: > On Wed, 28 Sep 2011 00:00:37 +0200 > Peter Zijlstra<a.p.zijlstra@chello.nl> wrote: > >> On Fri, 2011-09-23 at 19:20 -0300, Glauber Costa wrote: >>> @@ -1039,6 +1035,8 @@ static void posix_cpu_timers_init(struct task_struct *tsk) >>> INIT_LIST_HEAD(&tsk->cpu_timers[2]); >>> } >>> >>> +struct task_group *task_group(struct task_struct *p); >> >> That doesn't appear to be actually used in this file.. >> >> Also, since there's already a for_each_possible_cpu() loop in that >> proc/stat function, would it yield some code improvement to make >> total_forks a cpu_usage_stat? >> >> I guess the whole cputime64_t crap gets in the way of that being >> natural... >> >> We could of course kill off the cputime64_t thing, its pretty pointless >> and its a u64 all over the board. I think Martin or Heiko created this >> stuff (although I might be wrong, my git tree doesn't go back that far). > > The reason to introduce cputime_t has been that different architecture > needed differently sized integers for their respective representation > of cputime. On x86-32 the number of ticks is recorded in a u32, on s390 > we needed a u64 for the cpu timer values. cputime64_t is needed for > cpustat and other sums of cputime that would overflow a cputime_t > (in particular on x86-32 with the u32 cputime_t and the u64 cputime64_t). > > Now we would convert everything to u64 but that would cause x86-32 to > use 64-bit arithmetic for the tick counter. If that is acceptable I > can't say. > If we get rid of cputime64_t, it doesn't mean we need to get rid of cputime_t. Or am I missing the point here?
We would still have to call an analogous of cputime_to_cputime64 before using it, but I get that where it matters, gcc can even make it void. And for all the rest, we do u64 math and typing and just get happy.
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