Re: [PATCH] String conversions for memory policy

[Christoph Lameter]

On Fri, 29 Jul 2005, Paul Jackson wrote:

> My first suspicion on reading it is that it might partially duplicate
> some string conversion code and syntax that is already present in
> the kernel for other purposes.  For example the nodelists might
> replicate the lists of numbers supported by bitmap_scnlistprintf
> and bitmap_parselist.

Ahh. Yes these allow to simplify things somewhat and allow more 
flexiblity when specifying nodelists for interleave. Wish there was 
something similar for zonelists. Thanks.

> micro-micro-language for describing memory policies, it is difficult to
> know what the syntax is, without reverse engineering it from the code.

Umm.. that is what we do all day but maybe you could have a look at my 
initial patch which actually included a description of the syntax which 
is a straighforward representation of the possible variations on a memory 
policy.

Diff to use bitmap_scnlistprintf and bitmap_parselist.

Index: linux-2.6.13-rc3-mm3/mm/mempolicy.c
===================================================================
--- linux-2.6.13-rc3-mm3.orig/mm/mempolicy.c	2005-07-29 17:49:41.000000000 -0700
+++ linux-2.6.13-rc3-mm3/mm/mempolicy.c	2005-07-29 17:52:13.000000000 -0700
@@ -1181,7 +1181,6 @@
 	char *p = buffer;
 	char *e = buffer + maxlen;
 	int first = 1;
-	int node;
 	struct zone **z;
 
 	if (!pol || pol->policy == MPOL_DEFAULT) {
@@ -1223,18 +1222,7 @@
 			return -ENOSPC;
 
 		p += sprintf(p, "interleave={");
-
-		for_each_node(node)
-			if (test_bit(node, pol->v.nodes)) {
-				if (!first)
-					*p++ = ',';
-				else
-					first = 0;
-				if (e < p + 2 /* min bytes that follow */ + 4 /* node number */)
-					return -ENOSPC;
-				p += sprintf(p, "%d", node);
-			}
-
+		p += bitmap_scnprintf(p, e-p-2, pol->v.nodes, MAX_NUMNODES);
 		*p++ = '}';
 		*p++ = 0;
 		return p-buffer;
@@ -1279,20 +1267,8 @@
 	} else if (strnicmp(buffer, "interleave={", 12) == 0) {
 
 		pol->policy = MPOL_INTERLEAVE;
-		p = buffer + 12;
-		bitmap_zero(pol->v.nodes, MAX_NUMNODES);
-
-		do {
-			node = simple_strtoul(p, &p, 10);
-
-			/* Check here for cpuset restrictions on nodes */
-			if (node >= MAX_NUMNODES || !node_online(node))
-				goto out;
-			set_bit(node, pol->v.nodes);
-
-		} while (*p++ == ',');
-
-		if (p[-1] != '}' || bitmap_empty(pol->v.nodes, MAX_NUMNODES))
+		if (bitmap_parselist(buffer + 12, pol->v.nodes, MAX_NUMNODES) ||
+		    bitmap_empty(pol->v.nodes, MAX_NUMNODES))
 			goto out;
 
 	} else if (strnicmp(buffer, "bind={", 6) == 0) {
-
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