linux-kernel - Re: [PATCH] sched: fix constructing the span cpu mask of sched domain

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Message-ID: <BANLkTikShtNvCcz5hfm5kgUwBwS1LqF9xg@mail.gmail.com>
Date:	Wed, 11 May 2011 22:10:34 +0800
From:	Hillf Danton <dhillf@...il.com>
To:	Peter Zijlstra <peterz@...radead.org>
Cc:	LKML <linux-kernel@...r.kernel.org>, Ingo Molnar <mingo@...e.hu>,
	Mike Galbraith <efault@....de>,
	Yong Zhang <yong.zhang0@...il.com>,
	Andreas Herrmann <andreas.herrmann3@....com>
Subject: Re: [PATCH] sched: fix constructing the span cpu mask of sched domain

On Wed, May 11, 2011 at 9:54 PM, Peter Zijlstra <peterz@...radead.org> wrote:
> On Wed, 2011-05-11 at 21:26 +0800, Hillf Danton wrote:
>> Your work for rewriting NUMA support, published at
>>          http://marc.info/?l=linux-kernel&m=130218515520540
>> is patched by changing how level is computed and by changing how it is
>> used to build the mask.
>>
>> When computing, some valid levels are lost in your work.
>>
>> When building mask, nodes are selected only if they have same distance,
>> thus nodes of less distance are also masked out since the computation of
>> level now is tough.
>>
>> Without MUNA hardware, I did not test the patch:(
>
> I do have a (tiny) NUMA box (2 nodes) but that actually booted with the
> old code too, Andreas Hermann from AMD (CC'ed) is usually willing to
> test such patches on somewhat larger systems. Please send a full patch
> against tip/master for him to apply.
>
Oh my God, I am not good at playing game with git, already laughed by many
guys on LKML. As you see, I delivered all works based on diff through 512K ADSL,
things like "git clone" sounds really monstrous.

Would you please, Peter, teach me how to play git, since I want to do more?

And the patch is delivered to Andreas this time.

Hillf
---

--- numa_by_peter.c	2011-05-11 20:22:10.000000000 +0800
+++ numa_by_hillf.c	2011-05-11 21:06:26.000000000 +0800
@@ -1,6 +1,5 @@
 static void sched_init_numa(void)
 {
-	int next_distance, curr_distance = node_distance(0, 0);
 	struct sched_domain_topology_level *tl;
 	int level = 0;
 	int i, j, k;
@@ -11,21 +10,34 @@ static void sched_init_numa(void)
 	if (!sched_domains_numa_distance)
 		return;

-	next_distance = curr_distance;
-	for (i = 0; i < nr_node_ids; i++) {
-		for (j = 0; j < nr_node_ids; j++) {
-			int distance = node_distance(0, j);
-			printk("distance(0,%d): %d\n", j, distance);
-			if (distance > curr_distance &&
-					(distance < next_distance ||
-					 next_distance == curr_distance))
-				next_distance = distance;
+	for (j = 0; j < nr_node_ids; j++) {
+		int distance = node_distance(0, j);
+		printk("distance(0,%d): %d\n", j, distance);
+		if (j == 0) {
+			sched_domains_numa_distance[j] = distance;
+			sched_domains_numa_levels = ++level;
+			continue;
 		}
-		if (next_distance != curr_distance) {
-			sched_domains_numa_distance[level++] = next_distance;
+		for (i = 0; i < level; i++) {
+			/* check if already exist */
+			if (distance == sched_domains_numa_distance[i])
+				goto next_node;
+			/* sort and insert it */
+			if (distance < sched_domains_numa_distance[i])
+				break;
+		}
+		if (i == level) {
+			sched_domains_numa_distance[level++] = distance;
 			sched_domains_numa_levels = level;
-			curr_distance = next_distance;
-		} else break;
+			continue;
+		}
+		for (k = level -1; k >= i; k--)
+			sched_domains_numa_distance[k+1] =
+			sched_domains_numa_distance[k];
+		sched_domains_numa_distance[i] = distance;
+		sched_domains_numa_levels = ++level;
+next_node:
+		;
 	}

 	sched_domains_numa_masks = kzalloc(sizeof(void *) * level, GFP_KERNEL);
@@ -44,8 +56,9 @@ static void sched_init_numa(void)
 			struct cpumask *mask =
 				per_cpu_ptr(sched_domains_numa_masks[i], j);

+			cpumask_clear(mask);
 			for (k = 0; k < nr_node_ids; k++) {
-				if (node_distance(cpu_to_node(j), k) >
+				if (node_distance(cpu_to_node(j), k) !=
 						sched_domains_numa_distance[i])
 					continue;
--
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