Handle different kernel clock resolutions

[IPROUTE]: Handle different kernel clock resolutions

Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>

diff --git a/tc/tc_core.c b/tc/tc_core.c
index e27254eb91143716806e40fc0594a68072d366a8..58155fbf7ce2aa75f4b6c7077a14a4db34115c68 100644 (file)
--- a/tc/tc_core.c
+++ b/tc/tc_core.c
@@ -23,9 +23,8 @@
 
 #include "tc_core.h"
 
-static __u32 t2us=1;
-static __u32 us2t=1;
 static double tick_in_usec = 1;
+static double clock_factor = 1;
 
 int tc_core_time2big(long time)
 {
@@ -48,12 +47,12 @@ long tc_core_tick2time(long tick)
 
 long tc_core_time2ktime(long time)
 {
-       return time;
+       return time * clock_factor;
 }
 
 long tc_core_ktime2time(long ktime)
 {
-       return ktime;
+       return ktime / clock_factor;
 }
 
 unsigned tc_calc_xmittime(unsigned rate, unsigned size)
@@ -98,16 +97,29 @@ int tc_calc_rtable(unsigned bps, __u32 *rtab, int cell_log, unsigned mtu,
 
 int tc_core_init()
 {
-       FILE *fp = fopen("/proc/net/psched", "r");
+       FILE *fp;
+       __u32 clock_res;
+       __u32 t2us;
+       __u32 us2t;
 
+       fp = fopen("/proc/net/psched", "r");
        if (fp == NULL)
                return -1;
 
-       if (fscanf(fp, "%08x%08x", &t2us, &us2t) != 2) {
+       if (fscanf(fp, "%08x%08x%08x", &t2us, &us2t, &clock_res) != 3) {
                fclose(fp);
                return -1;
        }
        fclose(fp);
-       tick_in_usec = (double)t2us/us2t;
+
+       /* compatibility hack: for old iproute binaries (ignoring
+        * the kernel clock resolution) the kernel advertises a
+        * tick multiplier of 1000 in case of nano-second resolution,
+        * which really is 1. */
+       if (clock_res == 1000000000)
+               t2us = us2t;
+
+       clock_factor  = (double)clock_res / TIME_UNITS_PER_SEC;
+       tick_in_usec = (double)t2us / us2t * clock_factor;
        return 0;
 }