Messages in this thread | | | Date | Wed, 28 Sep 2011 12:27:41 -0300 | From | Glauber Costa <> | Subject | Re: [RFD 4/9] Make total_forks per-cgroup |
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On 09/28/2011 07:35 AM, Peter Zijlstra wrote: > On Wed, 2011-09-28 at 10:13 +0200, 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. > > Right, so the main point was about cputime64_t, we might as well use a > u64 for that throughout and ditch the silly cputime64_$op() accessors > and write normal code. > > But even if cputime_t differs between 32 and 64 bit machines, there is > no reason actually use cputime_add(), C can do this. > > The only reason to use things like cputime_add() is if you use a non > simple type, but that doesn't seem to be the case. > > So I think we can simplify the code lots by doing away with cputime64_t > and all the cputime_*() functions. We can keep cputime_t, or we can use > unsigned long, which I think will end up doing pretty much the same. for cputime64, I'm with you here. (so far) > > That is, am I missing some added value of all this cputime*() foo?
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