[Xen-devel] [PATCH 2/2] tools: utility to dump guest grant table info

[Dongli Zhang <dongli.zhang@xxxxxxxxxx>]

As both xen-netfront and xen-blkfront support multi-queue, they would
consume a lot of grant table references when there are many paravirtual
devices and vcpus assigned to guest. Guest domU might panic or hang due to
grant allocation failure when nr_grant_frames in guest has reached its max
value.

This utility would help the administrators to monitor the guest grant table
frame usage on dom0 side so that it is not required to debug on guest
kernel side for crash/hang analysis anymore.

Signed-off-by: Dongli Zhang <dongli.zhang@xxxxxxxxxx>
---
 tools/misc/Makefile           |  4 ++++
 tools/misc/xen-gnttab-query.c | 45 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 49 insertions(+)
 create mode 100644 tools/misc/xen-gnttab-query.c

diff --git a/tools/misc/Makefile b/tools/misc/Makefile
index 8152f7b..d081b4b 100644
--- a/tools/misc/Makefile
+++ b/tools/misc/Makefile
@@ -31,6 +31,7 @@ INSTALL_SBIN                   += xenperf
 INSTALL_SBIN                   += xenpm
 INSTALL_SBIN                   += xenwatchdogd
 INSTALL_SBIN                   += xen-livepatch
+INSTALL_SBIN                   += xen-gnttab-query
 INSTALL_SBIN += $(INSTALL_SBIN-y)
 
 # Everything to be installed in a private bin/
@@ -108,4 +109,7 @@ xen-lowmemd: xen-lowmemd.o
 xencov: xencov.o
        $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
 
+xen-gnttab-query: xen-gnttab-query.o
+       $(CC) $(LDFLAGS) -o $@ $< $(LDLIBS_libxenctrl) $(APPEND_LDFLAGS)
+
 -include $(DEPS)
diff --git a/tools/misc/xen-gnttab-query.c b/tools/misc/xen-gnttab-query.c
new file mode 100644
index 0000000..3f93a6c
--- /dev/null
+++ b/tools/misc/xen-gnttab-query.c
@@ -0,0 +1,45 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <err.h>
+#include <xenctrl.h>
+
+void show_help(void)
+{
+    fprintf(stderr,
+            "xen-gnttab-query: query grant table info\n"
+            "Usage: xen-gnttab-query [domid (default 0)]\n");
+}
+
+int main(int argc, char *argv[])
+{
+    xc_interface *xch;
+    int domid, rc, c;
+    struct gnttab_query_size query;
+
+    while ( (c = getopt(argc, argv, "h")) != -1 )
+    {
+        switch ( c )
+        {
+        case 'h':
+            show_help();
+            return 0;
+        }
+    }
+
+    domid = (argc > 1) ? strtol(argv[1], NULL, 10) : 0;
+
+    xch = xc_interface_open(0, 0, 0);
+    if ( !xch )
+        errx(1, "failed to open control interface");
+
+    query.dom = domid;
+    rc = xc_gnttab_query_size(xch, &query);
+
+    if ( rc == 0 && (query.status == GNTST_okay) )
+        printf("domid=%d: nr_frames=%d, max_nr_frames=%d\n",
+               query.dom, query.nr_frames, query.max_nr_frames);
+
+    xc_interface_close(xch);
+
+    return 0;
+}
-- 
2.7.4


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