Messages in this thread Patch in this message |  | | Date | Wed, 31 Jan 2007 20:31:55 +0530 | From | Srivatsa Vaddagiri <> | Subject | Re: [PATCH 1/2] core scheduler changes |
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On Fri, Jan 26, 2007 at 11:33:17AM +0530, Srivatsa Vaddagiri wrote: > > This patch does several things: > > - Introduces the notion of control window (current set at 1 > sec - ideally the window size should be adjusted based on > number of users to avoid rapid context switches). Bandwidth of each > user is controlled within this window. rq->last_update tracks where > are in the current window.
The patch below makes the control window size configurable (as a macro), sets the default window size at 10 sec and also fixes a compile error (for !CONFIG_FAIRSCHED case).
Ideally the window size needs to be determined at run time (based on number of users). I will address that if there is sufficient interest on a patch like this ..
Signed-off-by : Srivatsa Vaddagiri <vatsa@in.ibm.com>
---
diff -puN kernel/sched.c~window-fix kernel/sched.c --- linux-2.6.20-rc5/kernel/sched.c~window-fix 2007-01-31 19:59:48.000000000 +0530 +++ linux-2.6.20-rc5-vatsa/kernel/sched.c 2007-01-31 20:08:57.000000000 +0530 @@ -769,17 +769,24 @@ static inline int is_user_starving(struc return 0; } -/* Are we past the 1-sec control window? If so, all groups get to renew their +#define WINDOW_SIZE (10*HZ) + +/* Are we past the control window? If so, all groups get to renew their * expired tokens. */ -static inline void adjust_control_window(void) +static inline void adjust_control_window(int force) { struct rq *rq = this_rq(); unsigned long delta; + if (force) { + rq->last_update = jiffies; + return; + } + delta = jiffies - rq->last_update; - if (delta >= HZ) - rq->last_update += (delta/HZ) * HZ; + if (delta >= WINDOW_SIZE) + rq->last_update += (delta/WINDOW_SIZE) * WINDOW_SIZE; } /* Account group's cpu usage */ @@ -788,7 +795,7 @@ static inline void inc_cpu_usage(struct struct user_struct *user = p->user; struct cpu_usage *cu; - adjust_control_window(); + adjust_control_window(0); if (!user->cpu_limit) return; @@ -803,7 +810,7 @@ static inline int task_over_cpu_limit(st struct user_struct *user = p->user; struct cpu_usage *cu; - adjust_control_window(); + adjust_control_window(0); if (!user->cpu_limit) return 0; @@ -811,7 +818,7 @@ static inline int task_over_cpu_limit(st cu = per_cpu_ptr(user->cpu_usage, task_cpu(p)); if (cu->last_update != rq->last_update) { /* Replenish tokens */ - cu->tokens += user->cpu_limit * HZ / 100; + cu->tokens += user->cpu_limit * WINDOW_SIZE / 100; cu->last_update = rq->last_update; } @@ -830,6 +837,7 @@ static int task_over_cpu_limit(struct ta static void set_tsk_starving(struct task_struct *p) { } static void clear_tsk_starving(struct task_struct *p) { } static int is_user_starving(struct task_struct *p) { return 0;} +static inline void adjust_control_window(int force) { } #endif /* CONFIG_FAIRSCHED */ @@ -3668,7 +3676,7 @@ pick_next_task: } if (task_over_cpu_limit(next)) - rq->last_update = jiffies; + adjust_control_window(1); if (!next->time_slice) next->time_slice = task_timeslice(next); clear_tsk_starving(next); _
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