From: Afzal Mohammed <afzal.mohd.ma@gmail.com>
To: linux-kernel@vger.kernel.org
Cc: Ingo Molnar <mingo@redhat.com>, Peter Zijlstra <peterz@infradead.org>
Subject: [PATCH] sched,fair: Remove > u32 weight handling for delta
Date: Mon, 6 Jul 2015 08:14:37 +0530 [thread overview]
Message-ID: <1436150677-1818-1-git-send-email-afzal.mohd.ma@gmail.com> (raw)
scaled down weight 'fact' would not be > u32 rather than unlikely as the
values being passed for delta is either NICE_O_LOAD or the weight of the
'se' which would be a value that can be accomodated in a u32. Remove the
initial > u32 handling on 'fact'.
9dbdb15553239 ("sched/fair: Rework sched_fair time accounting") in
addition to fixing the original issue of time moving backwards elsewhere
in the code, handled delta > u32 case (due to NO_HZ_FULL) which brought
in as it's part the change changed here. The hunk being removed here
would not make a difference to it as this is on scaled weight > u32.
And pre-"9dbdb15553239" doesn't seem to have logical equivalent of hunk
removed here either.
Signed-off-by: Afzal Mohammed <afzal.mohd.ma@gmail.com>
---
System here (that mainly does kernel build) has been running with this
change for last couple of weeks without any issue observed.
kernel/sched/fair.c | 7 -------
1 file changed, 7 deletions(-)
diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
index 3d57cc0ca0a6..0cc58a7bdd16 100644
--- a/kernel/sched/fair.c
+++ b/kernel/sched/fair.c
@@ -218,13 +218,6 @@ static u64 __calc_delta(u64 delta_exec, unsigned long weight, struct load_weight
__update_inv_weight(lw);
- if (unlikely(fact >> 32)) {
- while (fact >> 32) {
- fact >>= 1;
- shift--;
- }
- }
-
/* hint to use a 32x32->64 mul */
fact = (u64)(u32)fact * lw->inv_weight;
--
2.1.4
next reply other threads:[~2015-07-06 2:45 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-07-06 2:44 Afzal Mohammed [this message]
2015-07-06 11:44 ` Peter Zijlstra
2015-07-06 13:34 ` Afzal Mohammed
2015-07-06 14:39 ` Afzal Mohammed
2015-07-06 18:19 ` [PATCH v2] " Afzal Mohammed
2015-08-12 11:12 ` Afzal Mohammed
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