On Tue, Dec 17, 2002 at 08:27:16AM +0000, Colin.Helliwell@Zarlink.Com wrote: > > NEW_TIME_C is set. URL to the patch is: > http://www.kernel.org/pub/linux/kernel/people/rml/preempt-kernel/v2.4/preempt-kernel-rml-2.4.19-2.patch > There are some bits missing. Not sure if it is related to your problem or not. Robert, please take the MIPS preemptible kernel update patch. > We ultimately want to add in real-time support, such as Ingo's O(1) > scheduler - if this is 'complete' for MIPS. O(1) shortens process dispatching time, usually not a big time saver unless you have *lots* of process and/or you are doing frequent context switches. Another patch which is probably more important is the Ingo's breaking selected big lock patch. That will preemption work more effectively. > I don't know if it would be > better just to go for this in one hit, or if we'd need the preemption > sorted out anyway first. You do have to sort them out one by one. (Or you get them all by becoming mvista customer. :-0) > Or should we just go to a 2.5.x kernel instead? We'd love to have more people bang on 2.5 MIPS *grin* ... Jun
Additional patch for MIPS against RML's 2.4.19-2 preemptiable kernel patch. http://www.kernel.org/pub/linux/kernel/people/rml/preempt-kernel/v2.4/preempt-kernel-rml-2.4.19-2.patch Jun diff -Nru link/arch/mips/kernel/irq.c.orig link/arch/mips/kernel/irq.c --- link/arch/mips/kernel/irq.c.orig Tue Dec 17 09:44:29 2002 +++ link/arch/mips/kernel/irq.c Tue Dec 17 09:44:45 2002 @@ -507,13 +507,13 @@ } current->preempt_count ++; - sti(); + __sti(); if (user_mode(regs)) { schedule(); } else { preempt_schedule(); } - cli(); + __cli(); } #endif diff -Nru link/arch/mips/kernel/time.c.orig link/arch/mips/kernel/time.c --- link/arch/mips/kernel/time.c.orig Mon Dec 2 16:56:03 2002 +++ link/arch/mips/kernel/time.c Tue Dec 17 09:53:37 2002 @@ -416,6 +416,8 @@ { int cpu = smp_processor_id(); + preempt_disable(); + irq_enter(cpu, irq); kstat.irqs[cpu][irq]++; @@ -426,12 +428,34 @@ if (softirq_pending(cpu)) do_softirq(); + +#if defined(CONFIG_PREEMPT) + while (--current->preempt_count == 0) { + db_assert(intr_off()); + db_assert(!in_interrupt()); + + if (current->need_resched == 0) { + break; + } + + current->preempt_count ++; + __sti(); + if (user_mode(regs)) { + schedule(); + } else { + preempt_schedule(); + } + __cli(); + } +#endif } asmlinkage void ll_local_timer_interrupt(int irq, struct pt_regs *regs) { int cpu = smp_processor_id(); + preempt_disable(); + irq_enter(cpu, irq); kstat.irqs[cpu][irq]++; @@ -442,6 +466,26 @@ if (softirq_pending(cpu)) do_softirq(); + +#if defined(CONFIG_PREEMPT) + while (--current->preempt_count == 0) { + db_assert(intr_off()); + db_assert(!in_interrupt()); + + if (current->need_resched == 0) { + break; + } + + current->preempt_count ++; + __sti(); + if (user_mode(regs)) { + schedule(); + } else { + preempt_schedule(); + } + __cli(); + } +#endif } /* diff -Nru link/include/asm-mips/softirq.h.orig link/include/asm-mips/softirq.h --- link/include/asm-mips/softirq.h.orig Tue Dec 17 09:44:29 2002 +++ link/include/asm-mips/softirq.h Tue Dec 17 09:54:13 2002 @@ -10,6 +10,9 @@ #ifndef _ASM_SOFTIRQ_H #define _ASM_SOFTIRQ_H +#include <linux/sched.h> +#include <linux/spinlock.h> + #include <asm/atomic.h> #include <asm/hardirq.h>
