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[Qemu-devel] Re: [PATCH 1/3] NUMA: add -numa command line option


From: Anthony Liguori
Subject: [Qemu-devel] Re: [PATCH 1/3] NUMA: add -numa command line option
Date: Fri, 12 Dec 2008 08:56:59 -0600
User-agent: Thunderbird 2.0.0.17 (X11/20080925)

Andre Przywara wrote:
This adds and parses a -numa command line option to QEMU.

Signed-off-by: Andre Przywara <address@hidden>

# HG changeset patch
# User Andre Przywara <address@hidden>
# Date 1228991781 -3600
# Node ID 394d02758aa4358be3bcd14f9d59efaf42e89328
# Parent  b3a4224604d267a0e406a6d6809947f342a6b2ed
introduce -numa command line option

diff -r b3a4224604d2 -r 394d02758aa4 sysemu.h
--- a/sysemu.h  Thu Dec 11 11:22:27 2008 +0100
+++ b/sysemu.h  Thu Dec 11 11:36:21 2008 +0100
@@ -92,6 +92,16 @@ extern int alt_grab;
 extern int alt_grab;
 extern int usb_enabled;
 extern int smp_cpus;
+
+#define MAX_NODES 64
+extern int numnumanodes;
+extern uint64_t hostnodes[MAX_NODES];

This should not be in this patch. This patch should just contain the bits needed to create a virtual guest NUMA topology. The hostnode stuff should be a separate patch.

+extern uint64_t node_mem[MAX_NODES];
+extern uint64_t node_to_cpus[MAX_NODES];
+
+int parse_numa_args (const char *opt, uint64_t *hostnodes, uint64_t *mems,
+                     uint64_t *cpus, int maxentries, int expect_numnodes);
+
 extern int cursor_hide;
 extern int graphic_rotate;
 extern int no_quit;
diff -r b3a4224604d2 -r 394d02758aa4 vl.c
--- a/vl.c      Thu Dec 11 11:22:27 2008 +0100
+++ b/vl.c      Thu Dec 11 11:36:21 2008 +0100
@@ -222,6 +222,10 @@ int win2k_install_hack = 0;
 #endif
 int usb_enabled = 0;
 int smp_cpus = 1;
+int numnumanodes = 0;
+uint64_t hostnodes[MAX_NODES];
+uint64_t node_mem[MAX_NODES];
+uint64_t node_to_cpus[MAX_NODES];
 const char *vnc_display;
 int acpi_enabled = 1;
 int fd_bootchk = 1;
@@ -3968,6 +3972,10 @@ static void help(int exitcode)
           "-daemonize      daemonize QEMU after initializing\n"
 #endif
           "-option-rom rom load a file, rom, into the option ROM space\n"
+           "-numa 
nrnodes[,mem:size1[;size2..]][,cpu:cpu1[;cpu2..]][,pin:node1[;node2]]\n"
+           "                create a multi NUMA node guest and optionally pin it 
to\n"
+           "                to the given host nodes. If mem and cpu are 
omitted,\n"
+           "                resources are split equally\n"

You're whitespace damaged.

+
+#define PARSE_FLAG_BITMASK   1
+#define PARSE_FLAG_SUFFIX    2
+
+static int parse_to_array (const char *arg, uint64_t *array,
+    char delim, int maxentries, int flags)
+{
+const char *s;
+char *end;
+int num = 0;
+unsigned long long int val,endval;

You're really whitespace damaged.

+    for (s = arg; s != NULL && *s != 0; s++) {
+        val = strtoull (s, &end, 10);
+        if (end == s && *s != '*') {num++; continue;}
+        if (num >= maxentries) break;
+        switch (*end) {
+            case 'g':
+            case 'G':
+                if (flags & PARSE_FLAG_SUFFIX) val *= 1024;
+               /* fall through */
+            case 'm':
+            case 'M':
+                if (flags & PARSE_FLAG_SUFFIX) val *= 1024;
+               /* fall through */
+            case 'k':
+            case 'K':
+                   if (flags & PARSE_FLAG_SUFFIX) val *= 1024;
+                   break;
+            case '*':
+                val = (unsigned long long int)-1;
+                break;
+            case '-':
+                   if (!(flags & PARSE_FLAG_BITMASK)) break;
+                s = end + 1;
+                endval = strtoull (s, &end, 10);
+                   val = (1 << (endval + 1)) - (1 << val);
+                break;
+            case 0:
+                   if (flags & PARSE_FLAG_SUFFIX) val *= 1024 * 1024;
+               /* fall through */
+            default:
+                   if (flags & PARSE_FLAG_BITMASK) val = 1 << val;
+                   break;
+        }
+        array[num++] = val;
+        if ((s = strchr (end, delim)) == NULL) break;
+    }
+    return num;
+}


This syntax is sufficiently complex that it needs thorough documentation (in qemu-doc.texi).

+int parse_numa_args (const char *opt, uint64_t *hostnodes, uint64_t *mems,
+                     uint64_t *cpus, int maxentries, int expect_numnodes)
+{
+const char *s;
+char *arg, *val, *end, *strtokarg;
+int num = 0;
+
+    arg = strdup(opt); strtokarg = arg;
+    if (expect_numnodes) {
+        s = strtok(strtokarg, ",");

strtok is generally evil.  strsep() is a better choice.

+        if (s == NULL) {free (arg); return -1;}

Don't do this one on line.

+        num = strtol (s, &end, 10);
+        if (s == end) {free (arg); return -1;}
+        strtokarg = NULL;
+    }
+    while ((s=strtok(strtokarg, ","))!=NULL) {
+        strtokarg = NULL;
+        if ((val = strchr (s, ':'))) {
+            *val++ = 0;
+            if (!strcmp (s, "mem") && mems != NULL) {
+                parse_to_array (val, mems, ';', maxentries, PARSE_FLAG_SUFFIX);
+            } else if (!strcmp (s, "cpu") && cpus != NULL) {
+                parse_to_array (val, cpus, ';', maxentries, 
PARSE_FLAG_BITMASK);
+            } else if (!strcmp (s, "pin") && hostnodes != NULL) {
+                parse_to_array (val, hostnodes, ';', maxentries, 0);
+            }
+        }
+    }
+    free (arg);
+    return num;
+

Please try to make things make the rest of qemu better. You have a lot of weird space after function names, etc. Consistency in large projects is important.

 int main(int argc, char **argv, char **envp)
 {
@@ -4556,6 +4648,12 @@ int main(int argc, char **argv, char **e
     for(i = 1; i < MAX_PARALLEL_PORTS; i++)
         parallel_devices[i] = NULL;
     parallel_device_index = 0;
+
+    for(i = 0; i < MAX_NODES; i++) {
+        hostnodes[i] = (uint64_t)-1;
+        node_to_cpus[i] = 0;
+        node_mem[i] = 0;
+    }
usb_devices_index = 0; @@ -5011,6 +5109,14 @@ int main(int argc, char **argv, char **e
                     exit(1);
                 }
                 break;
+            case QEMU_OPTION_numa:
+                numnumanodes = parse_numa_args (optarg,
+                    hostnodes, node_mem, node_to_cpus, MAX_NODES, 1);
+                if (numnumanodes < 0) {
+                    fprintf(stderr, "Invalid number of NUMA nodes\n");
+                    exit(1);
+                }
+                break;
            case QEMU_OPTION_vnc:
                vnc_display = optarg;
                break;
@@ -5151,6 +5257,24 @@ int main(int argc, char **argv, char **e
            monitor_device = "stdio";
     }
+ if (numnumanodes > 0) {
+        int i;
+
+        if (numnumanodes > smp_cpus)
+            numnumanodes = smp_cpus;

Why have this limitation? We would like to see CPU-less nodes supported either as memory-only nodes or as IO nodes.

Which leads me to the question of how to plan on describing which nodes have what hardware?

Regards,

Anthony Liguori




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