From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755631Ab3AXTyu (ORCPT ); Thu, 24 Jan 2013 14:54:50 -0500 Received: from mx1.redhat.com ([209.132.183.28]:16129 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755538Ab3AXTyo (ORCPT ); Thu, 24 Jan 2013 14:54:44 -0500 Date: Thu, 24 Jan 2013 13:54:27 -0600 From: Clark Williams To: Ingo Molnar Cc: Peter Zijlstra , Thomas Gleixner , Ingo Molnar , LKML , Steven Rostedt Subject: Re: [PATCH v2] sched: add a tuning knob to allow changing RR tmeslice Message-ID: <20130124135427.1748d057@redhat.com> In-Reply-To: <20130124165955.GA9324@gmail.com> References: <20121108195113.2dd51d43@redhat.com> <20130124165955.GA9324@gmail.com> Organization: Red Hat, Inc Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/rvckKy/1O6UqZ/Qn9=CPsmK"; protocol="application/pgp-signature" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --Sig_/rvckKy/1O6UqZ/Qn9=CPsmK Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 24 Jan 2013 17:59:55 +0100 Ingo Molnar wrote: >=20 > * Clark Williams wrote: >=20 > > This version stores the user-input value in a separate=20 > > location from the jiffies values used by the scheduler, to=20 > > prevent a race condition. > >=20 > > Subject: [PATCH v2] sched: add a tuning knob to allow changing=20 > > RR timeslice >=20 > looks useful. >=20 > > @@ -2010,7 +2010,7 @@ static void task_tick_rt(struct rq *rq, struct > > task_struct *p, int queued) if (--p->rt.time_slice) > > return; > > =20 > > - p->rt.time_slice =3D RR_TIMESLICE; > > + p->rt.time_slice =3D sched_rr_timeslice; > > =20 > > /* > > * Requeue to the end of queue if we (and all of our > > ancestors) are the @@ -2041,7 +2041,7 @@ static unsigned int > > get_rr_interval_rt(struct rq *rq, struct task_struct *task) > > * Time slice is 0 for SCHED_FIFO tasks >=20 > Patch wont apply due to patch corruption, alas. >=20 >=20 Easily fixed. Modified for 3.8-rc4: commit 0e2d40c5c84d06670f85cc212591f27f69f59c62 Author: Clark Williams Date: Thu Jan 24 13:51:01 2013 -0600 [kernel] sched: add a tuning knob to allow changing RR timeslice =20 Add a /proc/sys/kernel scheduler knob named sched_rr_timeslice_ms that allows global changing of the SCHED_RR timeslice value. User visable value is in milliseconds but is stored as jiffies. Setting to 0 (zero) resets to the default (currently 100ms). =20 Signed-off-by: Clark Williams diff --git a/include/linux/sched.h b/include/linux/sched.h index 6fc8f45..d803690 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -2082,6 +2082,11 @@ int sched_rt_handler(struct ctl_table *table, int wr= ite, void __user *buffer, size_t *lenp, loff_t *ppos); =20 +extern int sched_rr_timeslice; +extern int sched_rr_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos); + #ifdef CONFIG_SCHED_AUTOGROUP extern unsigned int sysctl_sched_autogroup_enabled; =20 diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 257002c..5675074 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -7507,6 +7507,24 @@ static int sched_rt_global_constraints(void) } #endif /* CONFIG_RT_GROUP_SCHED */ =20 +int sched_rr_handler(struct ctl_table *table, int write, + void __user *buffer, size_t *lenp, + loff_t *ppos) +{ + int ret; + static DEFINE_MUTEX(mutex); + + mutex_lock(&mutex); + ret =3D proc_dointvec(table, write, buffer, lenp, ppos); + /* make sure that internally we keep jiffies */ + /* also, writing zero resets timeslice to default */ + if (!ret && write)=20 + sched_rr_timeslice =3D sched_rr_timeslice <=3D 0 ?=20 + RR_TIMESLICE : msecs_to_jiffies(sched_rr_timeslice); + mutex_unlock(&mutex); + return ret; +} + int sched_rt_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp, loff_t *ppos) diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c index 418feb0..6c54e83 100644 --- a/kernel/sched/rt.c +++ b/kernel/sched/rt.c @@ -11,6 +11,8 @@ static int do_sched_rt_period_timer(struct rt_bandwidth *= rt_b, int overrun); =20 struct rt_bandwidth def_rt_bandwidth; =20 +int sched_rr_timeslice =3D RR_TIMESLICE; + static enum hrtimer_restart sched_rt_period_timer(struct hrtimer *timer) { struct rt_bandwidth *rt_b =3D @@ -2010,7 +2012,7 @@ static void task_tick_rt(struct rq *rq, struct task_s= truct *p, int queued) if (--p->rt.time_slice) return; =20 - p->rt.time_slice =3D RR_TIMESLICE; + p->rt.time_slice =3D sched_rr_timeslice; =20 /* * Requeue to the end of queue if we (and all of our ancestors) are the @@ -2041,7 +2043,7 @@ static unsigned int get_rr_interval_rt(struct rq *rq,= struct task_struct *task) * Time slice is 0 for SCHED_FIFO tasks */ if (task->policy =3D=3D SCHED_RR) - return RR_TIMESLICE; + return sched_rr_timeslice; else return 0; } diff --git a/kernel/sysctl.c b/kernel/sysctl.c index c88878d..1eabf86 100644 --- a/kernel/sysctl.c +++ b/kernel/sysctl.c @@ -403,6 +403,14 @@ static struct ctl_table kern_table[] =3D { .mode =3D 0644, .proc_handler =3D sched_rt_handler, }, + { + .procname =3D "sched_rr_timeslice_ms", + .data =3D &sched_rr_timeslice, + .maxlen =3D sizeof(int), + .mode =3D 0644, + .proc_handler =3D sched_rr_handler, + }, + #ifdef CONFIG_SCHED_AUTOGROUP { .procname =3D "sched_autogroup_enabled", --Sig_/rvckKy/1O6UqZ/Qn9=CPsmK Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v2.0.19 (GNU/Linux) iEYEARECAAYFAlEBkXMACgkQHyuj/+TTEp14NQCg5H5R8ze7zzOuwNNNrCbgLDMw R1QAni/xtcDXdWK+a+WWNSRpQoAycYm3 =IbKB -----END PGP SIGNATURE----- --Sig_/rvckKy/1O6UqZ/Qn9=CPsmK--