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 b5e362fa8ffa76708dbc2d78a2e83344979664b8..9ae4d8e5e7e9f0da847ff2074b464111bae9f7ad 100644 (file)
--- a/tc/tc_core.c
+++ b/tc/tc_core.c
@@ -84,11 +84,12 @@ int tc_calc_rtable(struct tc_ratespec *r, __u32 *rtab, int cell_log, unsigned mt
                        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;
 }