scheduler-ticker > 1000Hz, nitromethane for linux ;-)
Subsystems (2)
cover scheduler-ticker > 1000Hz, nitromethane for linux ;-)
Hi all,
this is a not fully serious (this is why I only post it here without sendig it directly via mail) patchset for:
* tune the scheduler at configuration point
* increase the ticker-frequency way above 1000Hz
* tune the ticker-freq. from userspace during runtime
Of course this increases your systems overhead, but it enables you to have more timer-triggered contexswitches per second and so (?)higher(?) interactivity. (Of course after tuning some scheduler-parameters, min_gran, wakeup_gran ...)
An interesting feature might be the userspace controlling of the tickerfreq, too. (Without disturbing HZ-dependend kernelcode, of course.)
I don't have very high hopes for an mainline integration ;-) but perhaps there are people, who want to play with such stuff.
The Code is more or less an excerise and perhaps some reviewing would be nice - so please contact me.
If (in the very unlikely case) there is enough interest in it, I can cleanup the code and start maintaining it...
* The patch is diffed against 3.2.7
* The whole patchset is also downloadable as an bzipped archive at:
http://www.matrixstorm.com/software/linux/nitromethane/linux-3.2.7-patches.tar.bz2
So now, please blame me "we don't need such s*it, it causes only overhead"... ;-)
regards Stephan
pub 4096R/FB9B12DB 2011-10-14 Stephan Bärwolf <[email protected]>
Primary key fingerprint: 2252 B41E 12DF 41AD 476F 7F36 084A 0911 FB9B 12DB
Stephan Baerwolf (10):
menuconfig: implement new submenu for extended scheduler-options
sched: implement the new menuconfig controlling of sched_tunables
menuconfig: extend nitro-menu by responsiveness nitro options
sched: implement the controlling of responsiveness-nitro-options
menuconfig: extend nitro-menu by HZ-frequency Nitro
hrtimer: implement the controlling of nitro-hzboost
menuconfig: extend nitro-menu by priority-nitro
sched: implement the controlling of priority-nitro
menuconfig: extend nitro-menu by userspace-multiplier hrtimer/sysctl: implement the controlling of userspace multiplier
arch/x86/Kconfig | 4 +- include/linux/sched.h | 8 ++ kernel/Kconfig.hz | 3 - kernel/Kconfig.sched | 202 +++++++++++++++++++++++++++++++++++++++++++ kernel/sched.c | 9 ++ kernel/sched_fair.c | 58 +++++++++++-- kernel/sysctl.c | 16 ++++ kernel/time/tick-common.c | 33 +++++++ kernel/time/tick-internal.h | 20 ++++ kernel/time/tick-sched.c | 51 +++++++++++ 10 files changed, 390 insertions(+), 14 deletions(-) create mode 100644 kernel/Kconfig.sched
Signature · 1 line
1.7.3.4
PATCH 1/1 nitro: make multiplier scaleable, change "nitro_hzmultiplicator" into "nitro_hz_permille"
This patch extends the conventional "nitro_hzmultiplicator" into a permille-base. So now it is possible also to scale down HZ. (For example half HZ would be possible with nitro_hz_permille=500, a quarter nitro_hz_permille=250 ...etc...) As always, jiffies_64 increases with HZ frequency.
The new proc-file is called "nitro_hz_permille"
The new config-option is called "CONFIG_SCHED_NITRO_HZBOOST_PERMILLE"
--- kernel/Kconfig.sched | 17 +++++++++-------- kernel/sysctl.c | 12 ++++++------ kernel/time/tick-common.c | 14 +++++++------- kernel/time/tick-internal.h | 19 ++++++++++++++----- 4 files changed, 36 insertions(+), 26 deletions(-)
kernel/Kconfig.sched +9 -8
@@ -176,23 +176,24 @@ config SCHED_NITRO_HZBOOST_USERSPAC accessable from userspace via procfs. The responsible file will be called /proc/sys/kernel/nitro_hzmultiplicator -config SCHED_NITRO_HZBOOST_MULTIPLICATOR - int "Multiply the HZ frequency value" - range 1 100 - default 1 +config SCHED_NITRO_HZBOOST_PERMILLE + int "Skale the HZ frequency value (per mille)" + range 1 100000 + default 1000 depends on (SCHED_NITRO_HZBOOST && X86_64 && SCHED_HRTICK) help Normally the scheduler code (scheduler_tick()) ticks with "HZ" frequency. With this frequency also "jiffies_64" is increased and is used by timerelated kernelcode. - This Option increases the schedulers tickerfrequency by multiplying - this multiplicator with HZ. However the jiffies_64 is STILL updated - with HZ-frequency and all the jiffy-based timecode is working further on. + This Option skales the schedulers tickerfrequency by multiplying + this per-mille value with HZ (and divides everything by 1000). + However the jiffies_64 is STILL updated with HZ-frequency and all the + jiffy-based timecode is working further on. Asyncron ns-time-based code will take advantage from this option and scheduling will become finer and more interactive. - WARNING: !! THIS OPTION WILL INCREASE YOUR "INTERRUPTS PER SECOND" FOR + WARNING: !! THIS OPTION MAY INCREASE YOUR "INTERRUPTS PER SECOND" FOR EACH ONLINE CPU. THIS WILL ALSO INCREASE YOUR SYSTEMOVERHEAD !! endmenu
kernel/sysctl.c +6 -6
@@ -253,8 +253,8 @@ static struct ctl_table root_table[] = {#ifdef CONFIG_SCHED_NITRO_HZBOOST_USERSPAC #include "time/tick-internal.h" -static int min_tick_period_HZmultiplicator =1 ; -static int max_tick_period_HZmultiplicator =100 ; +static int min_tick_period_HZscalepermille =1 ; +static int max_tick_period_HZscalepermille =100000 ;#endif #ifdef CONFIG_SCHED_DEBUG static int min_sched_granularity_ns =100000 ;/* 100 usecs */
@@ -280,13 +280,13 @@ static struct ctl_table kern_table[] = { }, #ifdef CONFIG_SCHED_NITRO_HZBOOST_USERSPAC { - .procname = "nitro_hzmultiplicator", - .data = &sysctl_tick_period_HZmultiplicator, + .procname = "nitro_hz_permille", + .data = &sysctl_tick_period_HZscalepermille, .maxlen = sizeof(unsigned int), .mode = 0644, .proc_handler = tick_change_periodmultiplicator_handler, - .extra1 = &min_tick_period_HZmultiplicator, - .extra2 = &max_tick_period_HZmultiplicator, + .extra1 = &min_tick_period_HZscalepermille, + .extra2 = &max_tick_period_HZscalepermille, }, #endif #ifdef CONFIG_SCHED_DEBUG
kernel/time/tick-common.c +7 -7
@@ -170,7 +170,7 @@ static void tick_setup_device(struct tick_device *td, tick_next_period =ktime_get ();#ifdef CONFIG_SCHED_NITRO_HZBOOST tick_HZbaseperiod =ktime_set (0 ,NSEC_PER_SEC /HZ ); -tick_change_periodmultiplicator (CONFIG_SCHED_NITRO_HZBOOST_MULTIPLICATOR ); +tick_change_periodmultiplicator (CONFIG_SCHED_NITRO_HZBOOST_PERMILLE );#else tick_period =ktime_set (0 ,NSEC_PER_SEC /HZ );#endif
@@ -427,8 +427,8 @@ void __init tick_init(void) }#ifdef CONFIG_SCHED_NITRO_HZBOOST_USERSPAC -unsigned int sysctl_tick_period_HZmultiplicator = ((unsigned long )CONFIG_SCHED_NITRO_HZBOOST_MULTIPLICATOR ); -static unsigned int __last_HZmultiplicator = ((unsigned long )CONFIG_SCHED_NITRO_HZBOOST_MULTIPLICATOR ); +unsigned int sysctl_tick_period_HZscalepermille = ((unsigned long )CONFIG_SCHED_NITRO_HZBOOST_PERMILLE ); +static unsigned int __last_HZscalepermille = ((unsigned long )CONFIG_SCHED_NITRO_HZBOOST_PERMILLE ); int tick_change_periodmultiplicator_handler(struct ctl_table *table, int write, void __user *buffer, size_t *lenp,
@@ -439,11 +439,11 @@ int tick_change_periodmultiplicator_handler(struct ctl_table *table, int write,if (ret || !write)return ret; -if (sysctl_tick_period_HZmultiplicator >0 ) -if (__last_HZmultiplicator != sysctl_tick_period_HZmultiplicator) { +if (sysctl_tick_period_HZscalepermille >0 ) +if (__last_HZscalepermille != sysctl_tick_period_HZscalepermille) {write_seqlock (&xtime_lock); -tick_change_periodmultiplicator (sysctl_tick_period_HZmultiplicator); - __last_HZmultiplicator = sysctl_tick_period_HZmultiplicator; +tick_change_periodmultiplicator (sysctl_tick_period_HZscalepermille); + __last_HZscalepermille = sysctl_tick_period_HZscalepermille;write_sequnlock (&xtime_lock); }
kernel/time/tick-internal.h +14 -5
@@ -17,19 +17,28 @@ extern int tick_do_timer_cpu __read_mostly;#ifdef CONFIG_SCHED_NITRO_HZBOOST extern ktime_t tick_HZbaseperiod;#ifdef CONFIG_SCHED_NITRO_HZBOOST_USERSPAC -extern unsigned int sysctl_tick_period_HZmultiplicator; +extern unsigned int sysctl_tick_period_HZscalepermille;extern int tick_change_periodmultiplicator_handler (struct ctl_table *table,int write,void __user *buffer,size_t *lenp,loff_t *ppos);#endif /* * proper locking has to be taken care outside +* +* scalepermille better be not zero! +* */ -static inline void tick_change_periodmultiplicator (const unsigned long long multiplicator) +static inline void tick_change_periodmultiplicator (const unsigned long long scalepermille) { -printk (KERN_NOTICE "changing nitro hzboost multiplicator, new frequency: %llu x %lluHz\n" , multiplicator, (unsigned long long )HZ ); - tick_period =ktime_set (0 ,NSEC_PER_SEC / (HZ *multiplicator)); -printk (KERN_NOTICE "scheduler nitro-patchset v1.0 Ilmenau 2012, by Stephan Baerwolf <[email protected]>\n" ); +unsigned long long __nanoseconds = (((unsigned long long )NSEC_PER_SEC ) *1000ULL ) / scalepermille; +unsigned int i,j; + + i = scalepermille /1000 ; + j = scalepermille %1000 ; + +printk (KERN_NOTICE "changing nitro hzboost multiplicator, new frequency: %u.%03u x %lluHz\n" , i, j, (unsigned long long )HZ ); + tick_period =ktime_set (0 , __nanoseconds / ((unsigned long long )HZ )); +printk (KERN_NOTICE "scheduler nitro-patchset v1.0.1 Ilmenau 2012, by Stephan Baerwolf <[email protected]>\n" ); }#endif
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1.7.3.4