Messages in this thread | | | Date | Wed, 12 Sep 2018 11:32:01 +0100 | From | Patrick Bellasi <> | Subject | Re: [PATCH v4 02/16] sched/core: uclamp: map TASK's clamp values into CPU's clamp groups |
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Hi Suren,
On 08-Sep 16:47, Suren Baghdasaryan wrote:
[...]
> > + * A clamp group is not free if there is at least one SE which is sing a clamp > > typo in the sentence
Right, s/is sing/is using/
+1
[...]
> > +static int > > +uclamp_group_find(int clamp_id, unsigned int clamp_value) > > +{ > > + struct uclamp_map *uc_map = &uclamp_maps[clamp_id][0]; > > + int free_group_id = UCLAMP_NOT_VALID; > > + unsigned int group_id = 0; > > + > > + for ( ; group_id <= CONFIG_UCLAMP_GROUPS_COUNT; ++group_id) { > > + /* Keep track of first free clamp group */ > > + if (uclamp_group_available(clamp_id, group_id)) { > > + if (free_group_id == UCLAMP_NOT_VALID) > > + free_group_id = group_id; > > + continue; > > + } > > Not a big improvement but reordering the two conditions in this loop > would avoid finding and recording free_group_id if the very first > group is the one we are looking for.
Right, indeed with:
uclamp_group_put() uclamp_group_reset() uclamp_group_init()
we always ensure that:
uc_map[group_id].value == UCLAMP_NOT_VALID
for free groups. Thus, it should be safe to swap this two checks and we likely save few instructions for a likely common case of non clamped tasks.
+1
I'll also get the chance to remove the two simple comments. ;)
> > + /* Return index of first group with same clamp value */ > > + if (uc_map[group_id].value == clamp_value) > > + return group_id; > > + } > > + > > + if (likely(free_group_id != UCLAMP_NOT_VALID)) > > + return free_group_id; > > + > > + return -ENOSPC; > > +}
[...]
> > +static inline void uclamp_group_put(int clamp_id, int group_id)
> Is the size and the number of invocations of this function small > enough for inlining? Same goes for uclamp_group_get() and especially > for __setscheduler_uclamp().
Right... yes, we could let the scheduler do its job and remove inline from these functions... at least for those not in the critical path.
+1
[...]
> > + if (likely(uc_map[group_id].se_count)) > > + uc_map[group_id].se_count -= 1; > > +#ifdef SCHED_DEBUG > > + else { > > nit: no need for braces > > > + WARN(1, "invalid SE clamp group [%d:%d] refcount\n", > > + clamp_id, group_id);
Since the above statement is multi-line, we actually need it for code code-style requirements.
> > + } > > +#endif
[...]
> > +static void uclamp_fork(struct task_struct *p, bool reset) > > +{ > > + int clamp_id; > > + > > + if (unlikely(!p->sched_class->uclamp_enabled)) > > + return; > > + > > + for (clamp_id = 0; clamp_id < UCLAMP_CNT; ++clamp_id) { > > + int next_group_id = p->uclamp[clamp_id].group_id; > > + struct uclamp_se *uc_se = &p->uclamp[clamp_id]; > > Might be easier to read if after the above assignment you use > uc_se->xxx instead of p->uclamp[clamp_id].xxx in the code below.
Yes, that's actually the intent of the above assigmenet... but I've forgot a couple of usages! +1
> > + > > + if (unlikely(reset)) { > > + next_group_id = 0; > > + p->uclamp[clamp_id].value = uclamp_none(clamp_id); > > + } > > + > > + p->uclamp[clamp_id].group_id = UCLAMP_NOT_VALID; > > + uclamp_group_get(clamp_id, next_group_id, uc_se, > > + p->uclamp[clamp_id].value); > > + } > > +}
[...]
> Thanks, > Suren.
Cheers, Patrick
-- #include <best/regards.h>
Patrick Bellasi
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