[IPROUTE]: Handle different kernel clock resolutions
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
[IPROUTE]: Replace "usec" by "time" in function names
Rename functions containing "usec" since they don't necessarily return
usec units anymore.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
[IPROUTE]: Introduce TIME_UNITS_PER_SEC to represent internal clock resolution
Introduce TIME_UNITS_PER_SEC and conversion functions between internal
resolution and resolution expected by the kernel (currently implemented as
NOPs, only needed by HFSC, which currently always uses microseconds).
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
[IPROUTE]: Introduce tc_calc_xmitsize and use where appropriate
Add tc_calc_xmitsize() as complement to tc_calc_xmittime(), which calculates
the size that can be transmitted at a given rate during a given time.
Replace all expressions of the form "size = rate*tc_core_tick2usec(time))/1000000"
by tc_calc_xmitsize() calls.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
[IPROUTE]: Use tc_calc_xmittime() where appropriate
Replace expressions of the form "tc_core_usec2tick(1000000 * size/rate)"
by tc_calc_xmittime().
The CBQ case deserves an extra comment: when called with bnwd=rate,
tc_cbq_calc_maxidle() behaves identical to tc_calc_xmittime():
unsigned tc_cbq_calc_maxidle(...)
{
double g = 1.0 - 1.0/(1<<ewma_log);
double xmt = (double)avpkt/bndw;
maxidle = xmt*(1-g);
if (bndw != rate && maxburst) {
...
}
return tc_core_usec2tick(maxidle*(1<<ewma_log)*1000000);
}
which comes down to:
maxidle = xmt * (1 - g)
= xmt * (1 - (1.0 - 1.0/(1 << ewma_log))
= xmt * (1.0/(1 << ewma_log))
so:
maxidle * (1 << ewma_log) * 1000000
= xmt * (1.0/(1 << ewma_log)) * (1 << ewma_log) * 1000000
= xmt * 1000000
= avpkt/bndw * 1000000
Which means tc_core_usec2tick(maxidle*(1<<ewma_log)*1000000) is identical
to tc_calc_xmittime(bndw, avpkt). Use it directly since its a lot easier
to understand its limits.
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
