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Subjectsched fixes 2.3.36
I spotted some scheduler bug in 2.3.36. I also increased the advantage of
avoiding a TLB flush. I did not benchmarks to check it's better but +1 is
way too low IMHO. Also it make a lots of sense to make it a per-arch thing
as tlb flushes hit changes across different archs (IA32 is probably one of
the most disavantaged without ASN). Now it's a define so every arch can
tune it:

diff -urN 2.3.36/include/asm-alpha/smp.h 2.3.36-sched/include/asm-alpha/smp.h
--- 2.3.36/include/asm-alpha/smp.h Wed Dec 29 22:55:04 1999
+++ 2.3.36-sched/include/asm-alpha/smp.h Thu Jan 6 01:37:38 2000
@@ -39,6 +39,7 @@
extern struct cpuinfo_alpha cpu_data[NR_CPUS];

#define PROC_CHANGE_PENALTY 20
+#define PROC_TLB_FLUSH_PENALTY 5

/* Map from cpu id to sequential logical cpu number. This will only
not be idempotent when cpus failed to come on-line. */
diff -urN 2.3.36/include/asm-i386/smp.h 2.3.36-sched/include/asm-i386/smp.h
--- 2.3.36/include/asm-i386/smp.h Fri Dec 31 00:03:32 1999
+++ 2.3.36-sched/include/asm-i386/smp.h Thu Jan 6 00:56:32 2000
@@ -259,7 +259,8 @@
* processes are run.
*/

-#define PROC_CHANGE_PENALTY 15 /* Schedule penalty */
+#define PROC_CHANGE_PENALTY 15 /* CPU Switch penalty */
+#define PROC_TLB_FLUSH_PENALTY 5 /* TLB flush penalty */

#endif
#endif
diff -urN 2.3.36/kernel/sched.c 2.3.36-sched/kernel/sched.c
--- 2.3.36/kernel/sched.c Wed Jan 5 17:42:52 2000
+++ 2.3.36-sched/kernel/sched.c Thu Jan 6 01:35:54 2000
@@ -141,8 +141,8 @@
#endif

/* .. and a slight advantage to the current MM */
- if (p->mm == this_mm)
- weight += 1;
+ if (p->mm == this_mm || !p->mm)
+ weight += PROC_TLB_FLUSH_PENALTY;
weight += p->priority;

out:
@@ -173,7 +173,7 @@
*/
static inline int preemption_goodness(struct task_struct * prev, struct task_struct * p, int cpu)
{
- return goodness(p, cpu, prev->mm) - goodness(prev, cpu, prev->mm);
+ return goodness(p, cpu, prev->active_mm) - goodness(prev, cpu, prev->active_mm);
}

/*
Andrea



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