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Commit 7b8577d9 authored by Patrick Bellasi's avatar Patrick Bellasi Committed by Andres Oportus
Browse files

sched/{fair,tune}: use reciprocal_value to compute boost margin 



Change-Id: I493b07360c46eee0b72c2a046dab9ec6cb3427ef
Signed-off-by: default avatarPatrick Bellasi <patrick.bellasi@arm.com>
Signed-off-by: default avatarSrinath Sridharan <srinathsr@google.com>
parent 41d9288e

kernel/sched/fair.c

+6 −17
Original line number Diff line number Diff line
@@ -5805,6 +5805,8 @@ static bool cpu_overutilized(int cpu) 


#ifdef CONFIG_SCHED_TUNE



struct reciprocal_value schedtune_spc_rdiv;



static long

schedtune_margin(unsigned long signal, long boost)

{
@@ -5815,29 +5817,16 @@ schedtune_margin(unsigned long signal, long boost) 
	 *

	 * The Boost (B) value is used to compute a Margin (M) which is

	 * proportional to the complement of the original Signal (S):

	 *   M = B * (SCHED_LOAD_SCALE - S), if B is positive

	 *   M = B * S, if B is negative

	 *   M = B * (SCHED_CAPACITY_SCALE - S)

	 * The obtained M could be used by the caller to "boost" S.

	 */

	if (boost >= 0) {

		margin  = SCHED_LOAD_SCALE - signal;

		margin  = SCHED_CAPACITY_SCALE - signal;

		margin *= boost;

	} else

		margin = -signal * boost;

	/*

	 * Fast integer division by constant:

	 *  Constant   :                 (C) = 100

	 *  Precision  : 0.1%            (P) = 0.1

	 *  Reference  : C * 100 / P     (R) = 100000

	 *

	 * Thus:

	 *  Shift bits : ceil(log(R,2))  (S) = 17

	 *  Mult const : round(2^S/C)    (M) = 1311

	 *

	 *

	 */

	margin  *= 1311;

	margin >>= 17;



	margin  = reciprocal_divide(margin, schedtune_spc_rdiv);



	if (boost < 0)

		margin *= -1;

kernel/sched/tune.c

+3 −0
Original line number Diff line number Diff line
@@ -17,6 +17,7 @@ static bool schedtune_initialized = false; 


unsigned int sysctl_sched_cfs_boost __read_mostly;



extern struct reciprocal_value schedtune_spc_rdiv;

extern struct target_nrg schedtune_target_nrg;



/* Performance Boost region (B) threshold params */
@@ -937,6 +938,8 @@ schedtune_init(void) 
	pr_info("schedtune: configured to support global boosting only\n");

#endif



	schedtune_spc_rdiv = reciprocal_value(100);



	return 0;



nodata: