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SubjectRe: [PATCH 2.5.52] NUMA scheduler (1/2)

diff -urN a/arch/i386/kernel/smpboot.c b/arch/i386/kernel/smpboot.c
--- a/arch/i386/kernel/smpboot.c 2002-12-16 03:07:56.000000000 +0100
+++ b/arch/i386/kernel/smpboot.c 2002-12-18 16:53:12.000000000 +0100
@@ -1202,6 +1202,9 @@
void __init smp_cpus_done(unsigned int max_cpus)
{
zap_low_mappings();
+#ifdef CONFIG_NUMA
+ build_node_data();
+#endif

I think it would be much nicer if you had a proper stub for !CONFIG_NUMA..

@@ -20,6 +20,7 @@
#include <asm/mmu.h>

#include <linux/smp.h>
+#include <asm/topology.h>

Another header in sched.h?? And it doesn't look like it's used at all.

#include <linux/sem.h>
#include <linux/signal.h>
#include <linux/securebits.h>
@@ -446,6 +447,9 @@
# define set_cpus_allowed(p, new_mask) do { } while (0)
#endif

+#ifdef CONFIG_NUMA
+extern void build_node_data(void);
+#endif

The ifdef is superflous.

diff -urN a/kernel/sched.c b/kernel/sched.c
--- a/kernel/sched.c 2002-12-16 03:08:14.000000000 +0100
+++ b/kernel/sched.c 2002-12-18 16:53:13.000000000 +0100
@@ -158,6 +158,10 @@
struct list_head migration_queue;

atomic_t nr_iowait;
+
+ unsigned long wait_time;
+ int wait_node;
+

Here OTOH a #if CONFIG_MUA could help to avoid a little bit of bloat.

} ____cacheline_aligned;
+#define cpu_to_node(cpu) __cpu_to_node(cpu)

I wonder why we don't have a proper cpu_to_node() yet, but as long
as it doesn't exist please use __cpu_to_node() directly.

+#define LOADSCALE 128

Any explanation?

+#ifdef CONFIG_NUMA

sched.c uses #if CONFIG_FOO, not #ifdef CONFIG_FOO, it would be cool
if you could follow the style of existing source files.

+/* Number of CPUs per node: sane values until all CPUs are up */
+int _node_nr_cpus[MAX_NUMNODES] = { [0 ... MAX_NUMNODES-1] = NR_CPUS };
+int node_ptr[MAX_NUMNODES+1]; /* first cpu of node (logical cpus are sorted!)*/
+#define node_ncpus(node) _node_nr_cpus[node]
Parametrized macros and variables aren't in the ßame namespace, what about
just node_nr_cpus for the macro, too. And should these be static?

+
+#define NODE_DELAY_IDLE (1*HZ/1000)
+#define NODE_DELAY_BUSY (20*HZ/1000)

Comments, please..

+/* the following macro implies that logical CPUs are sorted by node number */
+#define loop_over_node(cpu,node) \
+ for(cpu=node_ptr[node]; cpu<node_ptr[node+1]; cpu++)
Move to asm/topology.h?

+ ptr=0;
+ for (n=0; n<numnodes; n++) {
You need to add lots of space to match Documentation/odingStyle.. :)

+ for (cpu = 0; cpu < NR_CPUS; cpu++) {
+ if (!cpu_online(cpu)) continue;
And linebreaks..

Btw, what about a for_each_cpu that has the cpu_online check in topology.h?

+ /* Wait longer before stealing if own node's load is average. */
+ if (NODES_BALANCED(avg_load,nd[this_node].average_load))
Shouldn't NODES_BALANCED shout less and be an inline called nodes_balanced?

+ this_rq->wait_node = busiest_node;
+ this_rq->wait_time = jiffies;
+ goto out;
+ } else
+ /* old most loaded node: check if waited enough */
+ if (jiffies - this_rq->wait_time < steal_delay)
+ goto out;
That indentation looks really strange, why not just

/* old most loaded node: check if waited enough */
} else if (jiffies - this_rq->wait_time < steal_delay)
goto out;
+
+ if ((!CPUS_BALANCED(nd[busiest_node].busiest_cpu_load,*nr_running))) {
Dito, the name shouts a bit too much

+#endif

#endif /* CONFIG_NUMA */
-#define BUSY_REBALANCE_TICK (HZ/4 ?: 1)
+#define BUSY_REBALANCE_TICK (HZ/5 ?: 1)

And explanation why you changed that constant?

p = req->task;
- cpu_dest = __ffs(p->cpus_allowed);
+ cpu_dest = __ffs(p->cpus_allowed & cpu_online_map);
+

This looks like a bugfix valid without the rest of the patch.
-
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