Re: [linux-audio-dev] new realtime scheduling policy

ok, new patch. with sysctl for /proc/sys/kernel/rtsched_{period,reserved}. a single limit for all rt fifo processes. same caveats as last time. rob --- pristine/linux-2.4.20/kernel/sched.c 2003-03-17 23:24:02.000000000 -0500 +++ linux/kernel/sched.c 2003-03-18 13:22:38.000000000 -0500 @@ -43,6 +43,12 @@ extern void immediate_bh(void); unsigned securebits = SECUREBITS_DEFAULT; /* systemwide security settings */ +unsigned long rt_period_start = 0; +unsigned long rt_period_end = 0; +unsigned long rt_period_remain = 0; +unsigned long rt_period_length = 50; +unsigned long rt_period_reserved = 45; + extern void mem_use(void); /* @@ -188,7 +194,35 @@ static inline int goodness(struct task_s * runqueue (taking priorities within processes * into account). */ + + + + /* + * check if we are in the right time period + * + * XXX if it burns though it's entire quantum and + * into the next ? + * + */ + if (jiffies >= rt_period_end) { + /* no, start over from now */ + rt_period_start = jiffies; + rt_period_end = rt_period_length + rt_period_start; + rt_period_remain = rt_period_reserved; + } + + /* + * is there any remaining time ? + * + */ + + if (rt_period_remain > 0) { weight = 1000 + p->rt_priority; + } else { + /* redundent, for clarity */ + weight = -1; + } + out: return weight; } --- pristine/linux-2.4.20/kernel/sysctl.c 2003-03-17 23:24:02.000000000 -0500 +++ linux/kernel/sysctl.c 2003-03-18 13:05:22.000000000 -0500 @@ -51,6 +51,11 @@ extern int sysrq_enabled; extern int core_uses_pid; extern int cad_pid; + +extern unsigned long rt_period_length; +extern unsigned long rt_period_reserved; + + /* this is needed for the proc_dointvec_minmax for [fs_]overflow UID and GID */ static int maxolduid = 65535; static int minolduid; @@ -260,6 +265,12 @@ static ctl_table kern_table[] = { {KERN_LOWLATENCY, "lowlatency", &enable_lowlatency, sizeof (int), 0644, NULL, &proc_dointvec}, #endif + + {KERN_FIFOSCHED_PERIOD, "rtsched-period", &rt_period_length, + sizeof (int), 0644, NULL, &proc_dointvec}, + {KERN_FIFOSCHED_RESERV, "rtsched-reserve", + &rt_period_reserved, sizeof (int), 0644, NULL, &proc_dointvec}, + {0} }; --- pristine/linux-2.4.20/include/linux/sysctl.h 2003-03-17 23:24:02.000000000 -0500 +++ linux/include/linux/sysctl.h 2003-03-18 13:03:37.000000000 -0500 @@ -125,6 +125,8 @@ enum KERN_TAINTED=53, /* int: various kernel tainted flags */ KERN_CADPID=54, /* int: PID of the process to notify on CAD */ KERN_LOWLATENCY=55, /* int: enable low latency scheduling */ + KERN_FIFOSCHED_PERIOD=56, /* max time rt processes can take up */ + KERN_FIFOSCHED_RESERV=57, /* "" */ }; --- pristine/linux-2.4.20/kernel/timer.c 2002-11-28 18:53:15.000000000 -0500 +++ linux/kernel/timer.c 2003-03-18 12:41:05.000000000 -0500 @@ -105,6 +105,16 @@ static struct list_head * run_timer_list #define NOOF_TVECS (sizeof(tvecs) / sizeof(tvecs[0])) +extern unsigned long rt_period_start; +extern unsigned long rt_period_end; +extern unsigned long rt_period_remain; +extern unsigned long rt_period_length; +extern unsigned long rt_period_reserved; + + + + + void init_timervecs (void) { int i; @@ -610,6 +620,15 @@ void update_process_times(int user_tick) p->need_resched = 1; } } + + if (p->policy == SCHED_FIFO) { + if (rt_period_remain == 0) { + p->need_resched = 1; + } else { + rt_period_remain--; + } + } + if (p->nice > 0) kstat.per_cpu_nice[cpu] += user_tick; else ---- Robert Melby Georgia Institute of Technology, Atlanta Georgia, 30332 uucp: ...!{decvax,hplabs,ncar,purdue,rutgers}!gatech!prism!gt4255a Internet: async(a)cc.gatech.edu