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From: Dario Faggioli <dario.faggioli@citrix.com>
To: xen-devel@lists.xenproject.org
Cc: Anshul Makkar <anshul.makkar@citrix.com>,
	George Dunlap <george.dunlap@citrix.com>
Subject: [PATCH 22/24] xen: credit2: "relax" CSCHED2_MAX_TIMER
Date: Wed, 17 Aug 2016 19:20:08 +0200	[thread overview]
Message-ID: <147145440828.25877.10082549766938645168.stgit@Solace.fritz.box> (raw)
In-Reply-To: <147145358844.25877.7490417583264534196.stgit@Solace.fritz.box>

Credit2 is already event based, rather than tick
based. This means, the time at which the (i+1)-eth
scheduling decision needs to happen is computed
during the i-eth scheduling decision, and a timer
is set accordingly.

If there's nothing imminent (or, the most imminent
event is really really really far away), it is
ok to say "well, let's double-check things in
a little bit anyway", but such 'little bit' does
not need to be too little, as, most likely, it's
just pure overhead.

The current period, for this "safety catch"-alike
timer is 2ms, which indeed is high, but it can
well be higher. In fact, benchmarks show that
setting it to 10ms --combined with other
optimizations-- does actually improve performance.

Signed-off-by: Dario Faggioli <dario.faggioli@citrix.com>
---
Cc: George Dunlap <george.dunlap@citrix.com>
Cc: Anshul Makkar <anshul.makkar@citrix.com>
---
 xen/common/sched_credit2.c |    2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/xen/common/sched_credit2.c b/xen/common/sched_credit2.c
index 21b1f91..6963872 100644
--- a/xen/common/sched_credit2.c
+++ b/xen/common/sched_credit2.c
@@ -152,7 +152,7 @@
 /* Reset: Value below which credit will be reset. */
 #define CSCHED2_CREDIT_RESET         0
 /* Max timer: Maximum time a guest can be run for. */
-#define CSCHED2_MAX_TIMER            MILLISECS(2)
+#define CSCHED2_MAX_TIMER            CSCHED2_CREDIT_INIT
 
 
 #define CSCHED2_IDLE_CREDIT                 (-(1<<30))


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  parent reply	other threads:[~2016-08-17 17:20 UTC|newest]

Thread overview: 84+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-08-17 17:17 [PATCH 00/24] sched: Credit1 and Credit2 improvements... and soft-affinity for Credit2! Dario Faggioli
2016-08-17 17:17 ` [PATCH 01/24] xen: credit1: small optimization in Credit1's tickling logic Dario Faggioli
2016-09-12 15:01   ` George Dunlap
2016-08-17 17:17 ` [PATCH 02/24] xen: credit1: fix mask to be used for tickling in Credit1 Dario Faggioli
2016-08-17 23:42   ` Dario Faggioli
2016-09-12 15:04     ` George Dunlap
2016-08-17 17:17 ` [PATCH 03/24] xen: credit1: return the 'time remaining to the limit' as next timeslice Dario Faggioli
2016-09-12 15:14   ` George Dunlap
2016-09-12 17:00     ` Dario Faggioli
2016-09-14  9:34       ` George Dunlap
2016-09-14 13:54         ` Dario Faggioli
2016-08-17 17:18 ` [PATCH 04/24] xen: credit2: properly schedule migration of a running vcpu Dario Faggioli
2016-09-12 17:11   ` George Dunlap
2016-08-17 17:18 ` [PATCH 05/24] xen: credit2: make tickling more deterministic Dario Faggioli
2016-08-31 17:10   ` anshul makkar
2016-09-05 13:47     ` Dario Faggioli
2016-09-07 12:25       ` anshul makkar
2016-09-13 11:13       ` George Dunlap
2016-09-29 15:24         ` Dario Faggioli
2016-09-13 11:28   ` George Dunlap
2016-09-30  2:22     ` Dario Faggioli
2016-08-17 17:18 ` [PATCH 06/24] xen: credit2: implement yield() Dario Faggioli
2016-09-13 13:33   ` George Dunlap
2016-09-29 16:05     ` Dario Faggioli
2016-09-20 13:25   ` George Dunlap
2016-09-20 13:37     ` George Dunlap
2016-08-17 17:18 ` [PATCH 07/24] xen: sched: don't rate limit context switches in case of yields Dario Faggioli
2016-09-20 13:32   ` George Dunlap
2016-09-29 16:46     ` Dario Faggioli
2016-08-17 17:18 ` [PATCH 08/24] xen: tracing: add trace records for schedule and rate-limiting Dario Faggioli
2016-08-18  0:57   ` Meng Xu
2016-08-18  9:41     ` Dario Faggioli
2016-09-20 13:50   ` George Dunlap
2016-08-17 17:18 ` [PATCH 09/24] xen/tools: tracing: improve tracing of context switches Dario Faggioli
2016-09-20 14:08   ` George Dunlap
2016-08-17 17:18 ` [PATCH 10/24] xen: tracing: improve Credit2's tickle_check and burn_credits records Dario Faggioli
2016-09-20 14:35   ` George Dunlap
2016-09-29 17:23     ` Dario Faggioli
2016-09-29 17:28       ` George Dunlap
2016-09-29 20:53         ` Dario Faggioli
2016-08-17 17:18 ` [PATCH 11/24] tools: tracing: handle more scheduling related events Dario Faggioli
2016-09-20 14:37   ` George Dunlap
2016-08-17 17:18 ` [PATCH 12/24] xen: libxc: allow to set the ratelimit value online Dario Faggioli
2016-09-20 14:43   ` George Dunlap
2016-09-20 14:45     ` Wei Liu
2016-09-28 15:44   ` George Dunlap
2016-08-17 17:19 ` [PATCH 13/24] libxc: improve error handling of xc Credit1 and Credit2 helpers Dario Faggioli
2016-09-20 15:10   ` Wei Liu
2016-08-17 17:19 ` [PATCH 14/24] libxl: allow to set the ratelimit value online for Credit2 Dario Faggioli
2016-08-22  9:21   ` Ian Jackson
2016-09-05 14:02     ` Dario Faggioli
2016-08-22  9:28   ` Ian Jackson
2016-09-28 15:37     ` George Dunlap
2016-09-30  1:03     ` Dario Faggioli
2016-09-28 15:39   ` George Dunlap
2016-08-17 17:19 ` [PATCH 15/24] xl: " Dario Faggioli
2016-09-28 15:46   ` George Dunlap
2016-08-17 17:19 ` [PATCH 16/24] xen: sched: factor affinity helpers out of sched_credit.c Dario Faggioli
2016-09-28 15:49   ` George Dunlap
2016-08-17 17:19 ` [PATCH 17/24] xen: credit2: soft-affinity awareness in runq_tickle() Dario Faggioli
2016-09-01 10:52   ` anshul makkar
2016-09-05 14:55     ` Dario Faggioli
2016-09-07 13:24       ` anshul makkar
2016-09-07 13:31         ` Dario Faggioli
2016-09-28 20:44   ` George Dunlap
2016-08-17 17:19 ` [PATCH 18/24] xen: credit2: soft-affinity awareness fallback_cpu() and cpu_pick() Dario Faggioli
2016-09-01 11:08   ` anshul makkar
2016-09-05 13:26     ` Dario Faggioli
2016-09-07 12:52       ` anshul makkar
2016-09-29 11:11   ` George Dunlap
2016-08-17 17:19 ` [PATCH 19/24] xen: credit2: soft-affinity awareness in load balancing Dario Faggioli
2016-09-02 11:46   ` anshul makkar
2016-09-05 12:49     ` Dario Faggioli
2016-08-17 17:19 ` [PATCH 20/24] xen: credit2: kick away vcpus not running within their soft-affinity Dario Faggioli
2016-08-17 17:20 ` [PATCH 21/24] xen: credit2: optimize runq_candidate() a little bit Dario Faggioli
2016-08-17 17:20 ` Dario Faggioli [this message]
2016-09-30 15:30   ` [PATCH 22/24] xen: credit2: "relax" CSCHED2_MAX_TIMER George Dunlap
2016-08-17 17:20 ` [PATCH 23/24] xen: credit2: optimize runq_tickle() a little bit Dario Faggioli
2016-09-02 12:38   ` anshul makkar
2016-09-05 12:52     ` Dario Faggioli
2016-08-17 17:20 ` [PATCH 24/24] xen: credit2: try to avoid tickling cpus subject to ratelimiting Dario Faggioli
2016-08-18  0:11 ` [PATCH 00/24] sched: Credit1 and Credit2 improvements... and soft-affinity for Credit2! Dario Faggioli
2016-08-18 11:49 ` Dario Faggioli
2016-08-18 11:53 ` Dario Faggioli

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