On 13-Mar 21:10, Peter Zijlstra wrote:

On Wed, Mar 13, 2019 at 05:09:40PM +0000, Patrick Bellasi wrote:

quoted

Yes, that should be possible... will look into splitting this out in
v8 to have something like:

---8<---
struct uclamp_req {
	/* Clamp value "requested" by a scheduling entity */
	unsigned int value		: bits_per(SCHED_CAPACITY_SCALE);
	unsigned int bucket_id		: bits_per(UCLAMP_BUCKETS);
	unsigned int active		: 1;
	unsigned int user_defined	: 1;
}

struct uclamp_eff {
	unsigned int value	        : bits_per(SCHED_CAPACITY_SCALE);
	unsigned int bucket_id	        : bits_per(UCLAMP_BUCKETS);
}

No, have _1_ type. There is no point what so ever to splitting this.

Also, what's @user_defined about, I don't think I've seen that in the
parent patch.

That's a flag added by one of the following patches, but with the
change you are suggesting below...

quoted

struct task_struct {
        // ...
        #ifdef CONFIG_UCLAMP_TASK
                struct uclamp_req uclamp_req[UCLAMP_CNT];
                struct uclamp_eff uclamp_eff[UCLAMP_CNT];

		struct uclamp_se uclamp[UCLAMP_CNT];
		struct uclamp_se uclamp_req[UCLAMP_CNT];

Where the first is the very same introduced in patch #1, and leaving it
in place avoids having to update the sites already using that (or start
#1 with the _eff name to avoid having to change things around?).

quoted

        #endif
        // ...
}

static inline struct uclamp_eff
uclamp_eff_get(struct task_struct *p, unsigned int clamp_id)
{
        struct uclamp_eff uc_eff = p->uclamp_eff[clamp_id];

just this ^, these lines seem like a superfluous duplication:

quoted

	uc_eff.bucket_id = p->uclamp_req[clamp_id].bucket_id;
	uc_eff.value = p->uclamp_req[clamp_id].value;

quoted

	if (unlikely(uc_eff.clamp_value > uclamp_default[clamp_id].value)) {
		uc_eff.clamp_value = uclamp_default[clamp_id].value;
		uc_eff.bucket_id = uclamp_default[clamp_id].bucket_id;

and:

		uc = uclamp_default[clamp_id];

... with things like the above line it becomes quite tricky to exploit
the uclamp_se bitfield to track additional flags.

I'll try to remove the need for the "user_defined" flag, as long as we
have only the "active" you we can still manage to keep it in uclamp_se.

If instead we really need more flags, we will likely have to move them
into a separate bitfield. :/

quoted

	}

        return uc_eff;
}

static inline void
uclamp_eff_set(struct task_struct *p, unsigned int clamp_id)
{
        p->uclamp_eff[clamp_id] = uclamp_eff_get(p, clamp_id);
}
---8<---

Is that what you mean ?

Getting there :-)

Yeah... let see :)


-- 
#include <best/regards.h>

Patrick Bellasi