[Xen-devel] [PATCH v2 3/3] xenstat: handle more than 1024 domains

[Juergen Gross <jgross@xxxxxxxx>]

get_domain_ids() in libxenstat used by read_attributes_qdisk() is
limited to 1024 domains. Remove that limit.

Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
---
 tools/xenstat/libxenstat/src/xenstat_qmp.c | 67 +++++++++++++-----------------
 1 file changed, 29 insertions(+), 38 deletions(-)

diff --git a/tools/xenstat/libxenstat/src/xenstat_qmp.c 
b/tools/xenstat/libxenstat/src/xenstat_qmp.c
index 5e261af..5104afb 100644
--- a/tools/xenstat/libxenstat/src/xenstat_qmp.c
+++ b/tools/xenstat/libxenstat/src/xenstat_qmp.c
@@ -356,18 +356,6 @@ static int qmp_connect(char *path)
        return s;
 }
 
-/* Get up to 1024 active domains */
-static xc_domaininfo_t *get_domain_ids(xc_interface *xc_handle, int *num_doms)
-{
-       xc_domaininfo_t *dominfo;
-
-       dominfo = calloc(1024, sizeof(xc_domaininfo_t));
-       if (dominfo == NULL)
-               return NULL;
-       *num_doms = xc_domain_getinfolist(xc_handle, 0, 1024, dominfo);
-       return dominfo;
-}
-
 /* Gather the qdisk statistics by querying QMP
    Resources: http://wiki.qemu.org/QMP and qmp-commands.hx from the qemu code
    QMP Syntax for entering command mode. This command must be issued before
@@ -398,44 +386,47 @@ void read_attributes_qdisk(xenstat_node * node)
 {
        char *cmd_mode = "{ \"execute\": \"qmp_capabilities\" }";
        char *query_blockstats_cmd = "{ \"execute\": \"query-blockstats\" }";
-       xc_domaininfo_t *dominfo = NULL;
+       xc_domaininfo_t dominfo[1024];
        unsigned char *qmp_stats, *val;
        char path[80];
        int i, qfd, num_doms;
+       domid_t next_domid = 0;
 
-       dominfo = get_domain_ids(node->handle->xc_handle, &num_doms);
-       if (dominfo == NULL)
-               return;
+       for (;;) {
+               num_doms = xc_domain_getinfolist(node->handle->xc_handle, 
next_domid, 1024, dominfo);
+               if (num_doms <= 0)
+                       return;
 
-       for (i=0; i<num_doms; i++) {
-               if (dominfo[i].domain <= 0)
-                       continue;
+               for (i=0; i<num_doms; i++) {
+                       if (dominfo[i].domain <= 0)
+                               continue;
 
-               /* Verify that qdisk disks are used with this VM */
-               snprintf(path, sizeof(path),"/local/domain/0/backend/qdisk/%i", 
dominfo[i].domain);
-               if ((val = xs_read(node->handle->xshandle, XBT_NULL, path, 
NULL)) == NULL)
-                       continue;
-               free(val);
+                       /* Verify that qdisk disks are used with this VM */
+                       snprintf(path, 
sizeof(path),"/local/domain/0/backend/qdisk/%i", dominfo[i].domain);
+                       if ((val = xs_read(node->handle->xshandle, XBT_NULL, 
path, NULL)) == NULL)
+                               continue;
+                       free(val);
 
-               /* Connect to this VMs QMP socket */
-               snprintf(path, sizeof(path), "/var/run/xen/qmp-libxenstat-%i", 
dominfo[i].domain);
-               if ((qfd = qmp_connect(path)) < 0) {
-                       continue;
-               }
+                       /* Connect to this VMs QMP socket */
+                       snprintf(path, sizeof(path), 
"/var/run/xen/qmp-libxenstat-%i", dominfo[i].domain);
+                       if ((qfd = qmp_connect(path)) < 0) {
+                               continue;
+                       }
 
-               /* First enable QMP capabilities so that we can query for data 
*/
-               if ((qmp_stats = qmp_query(qfd, cmd_mode)) != NULL) {
-                       free(qmp_stats);
-                       /* Query QMP for this VMs blockstats */
-                       if ((qmp_stats = qmp_query(qfd, query_blockstats_cmd)) 
!= NULL) {
-                               qmp_parse_stats(node, dominfo[i].domain, 
qmp_stats, qfd);
+                       /* First enable QMP capabilities so that we can query 
for data */
+                       if ((qmp_stats = qmp_query(qfd, cmd_mode)) != NULL) {
                                free(qmp_stats);
+                               /* Query QMP for this VMs blockstats */
+                               if ((qmp_stats = qmp_query(qfd, 
query_blockstats_cmd)) != NULL) {
+                                       qmp_parse_stats(node, 
dominfo[i].domain, qmp_stats, qfd);
+                                       free(qmp_stats);
+                               }
                        }
+                       close(qfd);
                }
-               close(qfd);
-       }
 
-       free(dominfo);
+               next_domid = dominfo[num_doms - 1].domain + 1;
+       }
 }
 
 #else /* !HAVE_YAJL_V2 */
-- 
2.6.2


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