Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 11 Jan 2003 22:52:40 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 11 Jan 2003 22:52:37 -0500 Received: from svr-ganmtc-appserv-mgmt.ncf.coxexpress.com ([24.136.46.5]:18187 "EHLO svr-ganmtc-appserv-mgmt.ncf.coxexpress.com") by vger.kernel.org with ESMTP id ; Sat, 11 Jan 2003 22:52:27 -0500 Subject: [PATCH] updated scheduler tunables From: Robert Love To: linux-kernel@vger.kernel.org Cc: mbligh@us.ibm.com Content-Type: text/plain Organization: Message-Id: <1042344081.834.23.camel@phantasy> Mime-Version: 1.0 X-Mailer: Ximian Evolution 1.2.1 (1.2.1-4) Date: 11 Jan 2003 23:01:22 -0500 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 10905 Lines: 291 Updated scheduler tuning patch against 2.5.56. This exports the core scheduler parameters via both procfs and sysctl: [22:56:51]rml@phantasy:~$ pef /proc/sys/sched/ child_penalty=95 exit_weight=3 interactive_delta=2 max_sleep_avg=2000 max_timeslice=100 min_timeslice=10 parent_penalty=100 prio_bonus_ratio=10 starvation_limit=2000 The major update here is parameter checking: the minimum values are checked to prevent bad parameters (primarily preventing a zero or negative one value in cases where they could cause a divide-by-zero). mbligh, I know this has been in your queue for awhile... this updated version should apply OK. Robert Love Documentation/filesystems/proc.txt | 87 +++++++++++++++++++++++++++++++++++++ include/linux/sysctl.h | 15 +++++- kernel/sched.c | 31 +++++++++---- kernel/sysctl.c | 44 ++++++++++++++++++ 4 files changed, 166 insertions(+), 11 deletions(-) diff -urN linux-2.5.56/Documentation/filesystems/proc.txt linux/Documentation/filesystems/proc.txt --- linux-2.5.56/Documentation/filesystems/proc.txt 2003-01-10 15:11:40.000000000 -0500 +++ linux/Documentation/filesystems/proc.txt 2003-01-11 22:19:41.000000000 -0500 @@ -37,6 +37,7 @@ 2.8 /proc/sys/net/ipv4 - IPV4 settings 2.9 Appletalk 2.10 IPX + 2.11 /proc/sys/sched - scheduler tunables ------------------------------------------------------------------------------ Preface @@ -1663,6 +1664,92 @@ gives the destination network, the router node (or Directly) and the network address of the router (or Connected) for internal networks. +2.11 /proc/sys/sched - scheduler tunables +----------------------------------------- + +Useful knobs for tuning the scheduler live in /proc/sys/sched. + +child_penalty +------------- + +Percentage of the parent's sleep_avg that children inherit. sleep_avg is +a running average of the time a process spends sleeping. Tasks with high +sleep_avg values are considered interactive and given a higher dynamic +priority and a larger timeslice. You typically want this some value just +under 100. + +exit_weight +----------- + +When a CPU hog task exits, its parent's sleep_avg is reduced by a factor of +exit_weight against the exiting task's sleep_avg. + +interactive_delta +----------------- + +If a task is "interactive" it is reinserted into the active array after it +has expired its timeslice, instead of being inserted into the expired array. +How "interactive" a task must be in order to be deemed interactive is a +function of its nice value. This interactive limit is scaled linearly by nice +value and is offset by the interactive_delta. + +max_sleep_avg +------------- + +max_sleep_avg is the largest value (in ms) stored for a task's running sleep +average. The larger this value, the longer a task needs to sleep to be +considered interactive (maximum interactive bonus is a function of +max_sleep_avg). + +max_timeslice +------------- + +Maximum timeslice, in milliseconds. This is the value given to tasks of the +highest dynamic priority. + +min_timeslice +------------- + +Minimum timeslice, in milliseconds. This is the value given to tasks of the +lowest dynamic priority. Every task gets at least this slice of the processor +per array switch. + +parent_penalty +-------------- + +Percentage of the parent's sleep_avg that it retains across a fork(). +sleep_avg is a running average of the time a process spends sleeping. Tasks +with high sleep_avg values are considered interactive and given a higher +dynamic priority and a larger timeslice. Normally, this value is 100 and thus +task's retain their sleep_avg on fork. If you want to punish interactive +tasks for forking, set this below 100. + +prio_bonus_ratio +---------------- + +Middle percentage of the priority range that tasks can receive as a dynamic +priority. The default value of 25% ensures that nice values at the +extremes are still enforced. For example, nice +19 interactive tasks will +never be able to preempt a nice 0 CPU hog. Setting this higher will increase +the size of the priority range the tasks can receive as a bonus. Setting +this lower will decrease this range, making the interactivity bonus less +apparent and user nice values more applicable. + +starvation_limit +---------------- + +Sufficiently interactive tasks are reinserted into the active array when they +run out of timeslice. Normally, tasks are inserted into the expired array. +Reinserting interactive tasks into the active array allows them to remain +runnable, which is important to interactive performance. This could starve +expired tasks, however, since the interactive task could prevent the array +switch. To prevent starving the tasks on the expired array for too long. the +starvation_limit is the longest (in ms) we will let the expired array starve +at the expense of reinserting interactive tasks back into active. Higher +values here give more preferance to running interactive tasks, at the expense +of expired tasks. Lower values provide more fair scheduling behavior, at the +expense of interactivity. The units are in milliseconds. + ------------------------------------------------------------------------------ Summary ------------------------------------------------------------------------------ diff -urN linux-2.5.56/include/linux/sysctl.h linux/include/linux/sysctl.h --- linux-2.5.56/include/linux/sysctl.h 2003-01-10 15:11:55.000000000 -0500 +++ linux/include/linux/sysctl.h 2003-01-11 22:19:41.000000000 -0500 @@ -66,7 +66,8 @@ CTL_DEV=7, /* Devices */ CTL_BUS=8, /* Busses */ CTL_ABI=9, /* Binary emulation */ - CTL_CPU=10 /* CPU stuff (speed scaling, etc) */ + CTL_CPU=10, /* CPU stuff (speed scaling, etc) */ + CTL_SCHED=11, /* scheduler tunables */ }; /* CTL_BUS names: */ @@ -157,6 +158,18 @@ VM_LOWER_ZONE_PROTECTION=20,/* Amount of protection of lower zones */ }; +/* Tunable scheduler parameters in /proc/sys/sched/ */ +enum { + SCHED_MIN_TIMESLICE=1, /* minimum process timeslice */ + SCHED_MAX_TIMESLICE=2, /* maximum process timeslice */ + SCHED_CHILD_PENALTY=3, /* penalty on fork to child */ + SCHED_PARENT_PENALTY=4, /* penalty on fork to parent */ + SCHED_EXIT_WEIGHT=5, /* penalty to parent of CPU hog child */ + SCHED_PRIO_BONUS_RATIO=6, /* percent of max prio given as bonus */ + SCHED_INTERACTIVE_DELTA=7, /* delta used to scale interactivity */ + SCHED_MAX_SLEEP_AVG=8, /* maximum sleep avg attainable */ + SCHED_STARVATION_LIMIT=9, /* no re-active if expired is starved */ +}; /* CTL_NET names: */ enum diff -urN linux-2.5.56/kernel/sched.c linux/kernel/sched.c --- linux-2.5.56/kernel/sched.c 2003-01-10 15:12:15.000000000 -0500 +++ linux/kernel/sched.c 2003-01-11 22:19:41.000000000 -0500 @@ -57,16 +57,29 @@ * Minimum timeslice is 10 msecs, default timeslice is 150 msecs, * maximum timeslice is 300 msecs. Timeslices get refilled after * they expire. + * + * They are configurable via /proc/sys/sched */ -#define MIN_TIMESLICE ( 10 * HZ / 1000) -#define MAX_TIMESLICE (300 * HZ / 1000) -#define CHILD_PENALTY 95 -#define PARENT_PENALTY 100 -#define EXIT_WEIGHT 3 -#define PRIO_BONUS_RATIO 25 -#define INTERACTIVE_DELTA 2 -#define MAX_SLEEP_AVG (2*HZ) -#define STARVATION_LIMIT (2*HZ) + +int min_timeslice = (10 * HZ) / 1000; +int max_timeslice = (300 * HZ) / 1000; +int child_penalty = 95; +int parent_penalty = 100; +int exit_weight = 3; +int prio_bonus_ratio = 25; +int interactive_delta = 2; +int max_sleep_avg = 2 * HZ; +int starvation_limit = 2 * HZ; + +#define MIN_TIMESLICE (min_timeslice) +#define MAX_TIMESLICE (max_timeslice) +#define CHILD_PENALTY (child_penalty) +#define PARENT_PENALTY (parent_penalty) +#define EXIT_WEIGHT (exit_weight) +#define PRIO_BONUS_RATIO (prio_bonus_ratio) +#define INTERACTIVE_DELTA (interactive_delta) +#define MAX_SLEEP_AVG (max_sleep_avg) +#define STARVATION_LIMIT (starvation_limit) /* * If a task is 'interactive' then we reinsert it in the active diff -urN linux-2.5.56/kernel/sysctl.c linux/kernel/sysctl.c --- linux-2.5.56/kernel/sysctl.c 2003-01-10 15:11:22.000000000 -0500 +++ linux/kernel/sysctl.c 2003-01-11 22:19:41.000000000 -0500 @@ -55,6 +55,15 @@ extern int cad_pid; extern int pid_max; extern int sysctl_lower_zone_protection; +extern int min_timeslice; +extern int max_timeslice; +extern int child_penalty; +extern int parent_penalty; +extern int exit_weight; +extern int prio_bonus_ratio; +extern int interactive_delta; +extern int max_sleep_avg; +extern int starvation_limit; /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */ static int maxolduid = 65535; @@ -112,6 +121,7 @@ static ctl_table kern_table[]; static ctl_table vm_table[]; +static ctl_table sched_table[]; #ifdef CONFIG_NET extern ctl_table net_table[]; #endif @@ -156,6 +166,7 @@ {CTL_FS, "fs", NULL, 0, 0555, fs_table}, {CTL_DEBUG, "debug", NULL, 0, 0555, debug_table}, {CTL_DEV, "dev", NULL, 0, 0555, dev_table}, + {CTL_SCHED, "sched", NULL, 0, 0555, sched_table}, {0} }; @@ -358,7 +369,38 @@ static ctl_table dev_table[] = { {0} -}; +}; + +static ctl_table sched_table[] = { + {SCHED_MAX_TIMESLICE, "max_timeslice", &max_timeslice, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &one, NULL}, + {SCHED_MIN_TIMESLICE, "min_timeslice", &min_timeslice, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &one, NULL}, + {SCHED_CHILD_PENALTY, "child_penalty", &child_penalty, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &zero, NULL}, + {SCHED_PARENT_PENALTY, "parent_penalty", &parent_penalty, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &zero, NULL}, + {SCHED_EXIT_WEIGHT, "exit_weight", &exit_weight, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &zero, NULL}, + {SCHED_PRIO_BONUS_RATIO, "prio_bonus_ratio", &prio_bonus_ratio, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &zero, NULL}, + {SCHED_INTERACTIVE_DELTA, "interactive_delta", &interactive_delta, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &zero, NULL}, + {SCHED_MAX_SLEEP_AVG, "max_sleep_avg", &max_sleep_avg, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &one, NULL}, + {SCHED_STARVATION_LIMIT, "starvation_limit", &starvation_limit, + sizeof(int), 0644, NULL, &proc_dointvec_minmax, + &sysctl_intvec, NULL, &zero, NULL}, + {0} +}; extern void init_irq_proc (void); - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/