tools/xentop: Fix cpu% sort order

In compare_cpu_pct(), there is a double -> unsigned long long converion when
calling compare().  In C, this discards the fractional part, resulting in an
out-of order sorting such as:

        NAME  STATE   CPU(sec) CPU(%)
       xendd --b---       4020    5.7
    icecream --b---       2600    3.8
    Domain-0 -----r       1060    1.5
        neon --b---        827    1.1
      cheese --b---        225    0.7
       pizza --b---        359    0.5
     cassini --b---        490    0.4
     fusilli --b---        159    0.2
         bob --b---        502    0.2
     blender --b---        121    0.2
       bread --b---         69    0.1
    chickpea --b---         67    0.1
      lentil --b---         67    0.1

Introduce compare_dbl() function and update compare_cpu_pct() to call it.

Fixes: 49839b535b78 ("Add xenstat framework.")
Signed-off-by: Leigh Brown <leigh@solinno.co.uk>
Reviewed-by: Andrew Cooper <andrew.cooper3@citrix.com>

diff --git a/tools/xentop/xentop.c b/tools/xentop/xentop.c
index f5a456fd4dfd493832854b65a2e9ebb972a60ff7..f5d6c19cf9f0f5f7b71b3fe803ef48497a45a8a7 100644 (file)
--- a/tools/xentop/xentop.c
+++ b/tools/xentop/xentop.c
@@ -85,6 +85,7 @@ static void set_delay(const char *value);
 static void set_prompt(const char *new_prompt, void (*func)(const char *));
 static int handle_key(int);
 static int compare(unsigned long long, unsigned long long);
+static int compare_dbl(double, double);
 static int compare_domains(xenstat_domain **, xenstat_domain **);
 static unsigned long long tot_net_bytes( xenstat_domain *, int);
 static bool tot_vbd_reqs(xenstat_domain *, int, unsigned long long *);
@@ -424,6 +425,16 @@ static int compare(unsigned long long i1, unsigned long long i2)
        return 0;
 }
 
+/* Compares two double precision numbers, returning -1,0,1 for <,=,> */
+static int compare_dbl(double d1, double d2)
+{
+       if (d1 < d2)
+               return -1;
+       if (d1 > d2)
+               return 1;
+       return 0;
+}
+
 /* Comparison function for use with qsort.  Compares two domains using the
  * current sort field. */
 static int compare_domains(xenstat_domain **domain1, xenstat_domain **domain2)
@@ -525,7 +536,7 @@ static double get_cpu_pct(xenstat_domain *domain)
 
 static int compare_cpu_pct(xenstat_domain *domain1, xenstat_domain *domain2)
 {
-       return -compare(get_cpu_pct(domain1), get_cpu_pct(domain2));
+       return -compare_dbl(get_cpu_pct(domain1), get_cpu_pct(domain2));
 }
 
 /* Prints cpu percentage statistic */