Patrick McHardy, Cite: 'its better to overestimate than underestimate
to stay in control of the queue'.
Illustrating the rate table array:
Legend description
rtab[x] : Array index x of rtab[x]
xmit_sz : Transmit size contained in rtab[x] (normally transmit time)
maps[a-b] : Packet sizes from a to b, will map into rtab[x]
Current/old rate table mapping (cell_log:3):
rtab[0]:=xmit_sz:0 maps[0-7]
rtab[1]:=xmit_sz:8 maps[8-15]
rtab[2]:=xmit_sz:16 maps[16-23]
rtab[3]:=xmit_sz:24 maps[24-31]
rtab[4]:=xmit_sz:32 maps[32-39]
rtab[5]:=xmit_sz:40 maps[40-47]
rtab[6]:=xmit_sz:48 maps[48-55]
New rate table mapping, with kernel cell_align support.
rtab[0]:=xmit_sz:8 maps[0-8]
rtab[1]:=xmit_sz:16 maps[9-16]
rtab[2]:=xmit_sz:24 maps[17-24]
rtab[3]:=xmit_sz:32 maps[25-32]
rtab[4]:=xmit_sz:40 maps[33-40]
rtab[5]:=xmit_sz:48 maps[41-48]
rtab[6]:=xmit_sz:56 maps[49-56]
New TC util on a kernel WITHOUT support for cell_align
rtab[0]:=xmit_sz:8 maps[0-7]
rtab[1]:=xmit_sz:16 maps[8-15]
rtab[2]:=xmit_sz:24 maps[16-23]
rtab[3]:=xmit_sz:32 maps[24-31]
rtab[4]:=xmit_sz:40 maps[32-39]
rtab[5]:=xmit_sz:48 maps[40-47]
rtab[6]:=xmit_sz:56 maps[48-55]
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Stephen Hemminger <stephen.hemminger@vyatta.com>
Change tc_calc_rtable() to take a tc_ratespec struct as an
argument. (cell_log still needs to be passed on as a parameter,
because -1 indicate that the cell_log needs to be computed by the
function.).
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Stephen Hemminger <stephen.hemminger@vyatta.com>
The only current user is HTB. HTB overhead argument is now passed on
to the kernel (in the struct tc_ratespec). Also correct the data
types.
Signed-off-by: Jesper Dangaard Brouer <hawk@comx.dk>
Signed-off-by: Stephen Hemminger <stephen.hemminger@vyatta.com>
tc_core_time2big only used in tc/q_netem.c where it gets passed an unsigned.
Signed-off-by: Andreas Henriksson <andreas@fatal.se>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Follow up patch to "Fix overflow in time2tick / tick2time." which switches
the remaining two helper functions from long to unsigned as well.
These functions are only used in "tc/q_hfsc.c" where both the passed argument
and the place the return value is stored are unsigned/u32 variables, so this
change should be safe to make but hasn't been tested as extensively as the
time2tick patch.
Signed-off-by: Andreas Henriksson <andreas@fatal.se>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
The helper functions gets passed an unsigned int, which gets cast to long
and overflows. See http://bugs.debian.org/175462
Signed-off-by: Andreas Henriksson <andreas@fatal.se>
Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
[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>
