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netem: use fixed rather than floating point for scaling 

Don't need to do floating point math to compute scaled random.

Signed-off-by: Stephen Hemminger <stephen@networkplumber.org>
This commit is contained in:
Stephen Hemminger 2017-11-07 11:15:34 +09:00
parent 0c7d651b38
commit e4beb52787
1 changed files with 5 additions and 7 deletions
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12
tc/q_netem.c
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@ -17,6 +17,7 @@
#include <unistd.h> #include <unistd.h>
#include <syslog.h> #include <syslog.h>
#include <fcntl.h> #include <fcntl.h>
#include <stdint.h>
#include <sys/socket.h> #include <sys/socket.h>
#include <netinet/in.h> #include <netinet/in.h>
#include <arpa/inet.h> #include <arpa/inet.h>
@ -53,15 +54,12 @@ static void explain1(const char *arg)
*/ */
#define MAX_DIST (16*1024) #define MAX_DIST (16*1024)
static const double max_percent_value = 0xffffffff;
/* scaled value used to percent of maximum. */ /* scaled value used to percent of maximum. */
static void set_percent(__u32 *percent, double per) static void set_percent(__u32 *percent, double per)
{ {
*percent = (unsigned int) rint(per * max_percent_value); *percent = rint(per * UINT32_MAX);
} }
/* Parse either a fraction '.3' or percent '30% /* Parse either a fraction '.3' or percent '30%
* return: 0 = ok, -1 = error, 1 = out of range * return: 0 = ok, -1 = error, 1 = out of range
*/ */
@ -89,7 +87,7 @@ static int get_percent(__u32 *percent, const char *str)
static void print_percent(char *buf, int len, __u32 per) static void print_percent(char *buf, int len, __u32 per)
{ {
snprintf(buf, len, "%g%%", 100. * (double) per / max_percent_value); snprintf(buf, len, "%g%%", (100. * per) / UINT32_MAX);
} }
static char *sprint_percent(__u32 per, char *buf) static char *sprint_percent(__u32 per, char *buf)
@ -323,7 +321,7 @@ static int netem_parse_opt(struct qdisc_util *qu, int argc, char **argv,
/* netem option is "1-h" but kernel /* netem option is "1-h" but kernel
* expects "h". * expects "h".
*/ */
gemodel.h = max_percent_value - gemodel.h; gemodel.h = UINT32_MAX - gemodel.h;
if (!NEXT_IS_NUMBER()) if (!NEXT_IS_NUMBER())
continue; continue;
@ -630,7 +628,7 @@ static int netem_print_opt(struct qdisc_util *qu, FILE *f, struct rtattr *opt)
fprintf(f, " loss gemodel p %s", fprintf(f, " loss gemodel p %s",
sprint_percent(gemodel->p, b1)); sprint_percent(gemodel->p, b1));
fprintf(f, " r %s", sprint_percent(gemodel->r, b1)); fprintf(f, " r %s", sprint_percent(gemodel->r, b1));
fprintf(f, " 1-h %s", sprint_percent(max_percent_value - fprintf(f, " 1-h %s", sprint_percent(UINT32_MAX -
gemodel->h, b1)); gemodel->h, b1));
fprintf(f, " 1-k %s", sprint_percent(gemodel->k1, b1)); fprintf(f, " 1-k %s", sprint_percent(gemodel->k1, b1));
} }