Change the rate table calc of transmit cost to use upper bound value.
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>
diff --git a/tc/tc_core.c b/tc/tc_core.c
index b5e362f..9ae4d8e 100644
--- a/tc/tc_core.c
+++ b/tc/tc_core.c
@@ -84,11 +84,12 @@
cell_log++;
}
for (i=0; i<256; i++) {
- unsigned sz = (i<<cell_log);
+ unsigned sz = ((i+1)<<cell_log);
if (sz < mpu)
sz = mpu;
rtab[i] = tc_calc_xmittime(bps, sz);
}
+ r->cell_align=-1; // Due to the sz calc
r->cell_log=cell_log;
return cell_log;
}