Messages in this thread Patch in this message | | | Date | Mon, 15 Mar 2004 23:42:01 +0100 | From | Kurt Garloff <> | Subject | dynamic sched timeslices |
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Hi,
attached patch allows userspace to tune the scheduling timeslices. It can be used for a couple of things: * Tune a workload for batch processing: You'd probably wnat to use long timeslices in order to not reschedule as often to make good use of your CPU caches * Tune a workload for interactive use: Under load, you may want to reduce the scedulilng latencies by using shorter timeslices (and there are situations where the interactiviy tweak -- even if they were perfect -- can't save you). * Tune the ration betweeen maximum and minimum timeslices to make nice much nicer e.g.
The patch exports /proc/sys/kernel/max_timeslice and min_timeslice, unites are us. It also exports HZ (readonly). The patch implementes the desktop boot parameter which introduces shorter timeslices.
Patch is from andrea and is in our 2.4 tree; 2.6 port was done by me and straightforward.
Regards, -- Kurt Garloff <garloff@suse.de> Cologne, DE SUSE LINUX AG, Nuernberg, DE SUSE Labs (Head) diff -uNrp linux-2.6.4/include/linux/sched.h linux-2.6.4.sched/include/linux/sched.h --- linux-2.6.4/include/linux/sched.h 2004-03-11 21:01:41.746772792 +0100 +++ linux-2.6.4.sched/include/linux/sched.h 2004-03-11 21:24:41.208062800 +0100 @@ -176,6 +176,7 @@ extern unsigned long cache_decay_ticks; #define MAX_SCHEDULE_TIMEOUT LONG_MAX extern signed long FASTCALL(schedule_timeout(signed long timeout)); asmlinkage void schedule(void); +extern int max_timeslice, min_timeslice; struct namespace; diff -uNrp linux-2.6.4/include/linux/sysctl.h linux-2.6.4.sched/include/linux/sysctl.h --- linux-2.6.4/include/linux/sysctl.h 2004-03-11 21:01:41.747772640 +0100 +++ linux-2.6.4.sched/include/linux/sysctl.h 2004-03-11 21:32:32.968344336 +0100 @@ -134,6 +134,9 @@ enum KERN_KDB=64, /* int: kdb on/off */ KERN_S390_HZ_TIMER=65, /* int: hz timer on or off */ KERN_DUMP=66, /* directory: dump parameters */ + KERN_MAXTIMESLICE=67, /* int: nice -20 max timeslice */ + KERN_MINTIMESLICE=68, /* int: nice +19 min timeslice */ + KERN_HZ=69, /* unsigned long: interal kernel HZ */ }; diff -uNrp linux-2.6.4/kernel/sched.c linux-2.6.4.sched/kernel/sched.c --- linux-2.6.4/kernel/sched.c 2004-03-11 21:01:41.752771880 +0100 +++ linux-2.6.4.sched/kernel/sched.c 2004-03-11 22:06:26.166251272 +0100 @@ -79,12 +79,19 @@ EXPORT_SYMBOL(dump_oncpu); /* * These are the 'tuning knobs' of the scheduler: * - * Minimum timeslice is 10 msecs, default timeslice is 100 msecs, - * maximum timeslice is 200 msecs. Timeslices get refilled after - * they expire. - */ -#define MIN_TIMESLICE ( 10 * HZ / 1000) -#define MAX_TIMESLICE (200 * HZ / 1000) + * Minimum timeslice is 10 msecs, default timeslice is 150 msecs, + * maximum timeslice is 300 msecs. Timeslices get refilled after + * they expire. + */ +#define __MIN_TIMESLICE 10000 +#define __MAX_TIMESLICE 300000 +#define __MIN_TIMESLICE_DESKTOP 2000 +#define __MAX_TIMESLICE_DESKTOP 60000 +/* the sysctl values are exported in usec units to userspace */ +int max_timeslice = __MAX_TIMESLICE, min_timeslice = __MIN_TIMESLICE; +#define MAX_TIMESLICE ((max_timeslice * HZ + 999999) / 1000000) +#define MIN_TIMESLICE ((min_timeslice * HZ + 999999) / 1000000) + #define ON_RUNQUEUE_WEIGHT 30 #define CHILD_PENALTY 95 #define PARENT_PENALTY 100 @@ -2965,3 +2972,13 @@ task_t *kdb_cpu_curr(int cpu) return(cpu_curr(cpu)); } #endif + +static int __init init_desktop(char *str) +{ + min_timeslice = __MIN_TIMESLICE_DESKTOP; + max_timeslice = __MAX_TIMESLICE_DESKTOP; + return 1; +} +__setup("desktop", init_desktop); + + diff -uNrp linux-2.6.4/kernel/sysctl.c linux-2.6.4.sched/kernel/sysctl.c --- linux-2.6.4/kernel/sysctl.c 2004-03-11 21:01:37.983344920 +0100 +++ linux-2.6.4.sched/kernel/sysctl.c 2004-03-11 21:36:26.253879544 +0100 @@ -167,6 +167,7 @@ static void register_proc_table(ctl_tabl static void unregister_proc_table(ctl_table *, struct proc_dir_entry *); #endif +static unsigned long __HZ = HZ; /* The default sysctl tables: */ static ctl_table root_table[] = { @@ -642,6 +643,30 @@ static ctl_table kern_table[] = { .mode = 0444, .proc_handler = &proc_dointvec, }, + { + .ctl_name = KERN_MAXTIMESLICE, + .procname = "max-timeslice", + .data = &max_timeslice, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, + { + .ctl_name = KERN_MINTIMESLICE, + .procname = "min-timeslice", + .data = &min_timeslice, + .maxlen = sizeof(int), + .mode = 0644, + .proc_handler = &proc_dointvec, + }, + { + .ctl_name = KERN_HZ, + .procname = "HZ", + .data = &__HZ, + .maxlen = sizeof(long), + .mode = 0444, + .proc_handler = &proc_dointvec, + }, { .ctl_name = 0 } }; [unhandled content-type:application/pgp-signature] | |