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netdev-linux: Make htb quantum always no less than mtu.

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Currently, ovs uses hardcoded rate2quantum = 10 for each htb qdisc.
When qdisc class's rate is small, the resulting quantum (calculated
by min_rate / rate2quantum) will be smaller than MTU.  This is not
recommended and tc will keep complaining the following in syslog.

localhost kernel: HTB: quantum of class 10003 is small. Consider r2q change.
localhost kernel: HTB: quantum of class 10004 is small. Consider r2q change.
localhost kernel: HTB: quantum of class 10005 is small. Consider r2q change.
localhost kernel: HTB: quantum of class 10006 is small. Consider r2q change.

To fix the issue, this commit makes ovs always use htb quantum no less
than the MTU.

Signed-off-by: Alex Wang <alexw@nicira.com>
Acked-by: Ben Pfaff <blp@nicira.com>
This commit is contained in:
Alex Wang
2015-03-27 11:34:53 -07:00
parent 618f44f7a4
commit 4f631ccd51
1 changed files with 7 additions and 1 deletions
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8
lib/netdev-linux.c
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@@ -3497,6 +3497,7 @@ static const struct tc_ops tc_ops_sfq = {
/* HTB traffic control class. */
#define HTB_N_QUEUES 0xf000
#define HTB_RATE2QUANTUM 10
struct htb {
struct tc tc;
@@ -3555,7 +3556,7 @@ htb_setup_qdisc__(struct netdev *netdev)
nl_msg_put_string(&request, TCA_KIND, "htb");
memset(&opt, 0, sizeof opt);
opt.rate2quantum = 10;
opt.rate2quantum = HTB_RATE2QUANTUM;
opt.version = 3;
opt.defcls = 1;
@@ -3589,6 +3590,11 @@ htb_setup_class__(struct netdev *netdev, unsigned int handle,
memset(&opt, 0, sizeof opt);
tc_fill_rate(&opt.rate, class->min_rate, mtu);
tc_fill_rate(&opt.ceil, class->max_rate, mtu);
/* Makes sure the quantum is at least MTU. Setting quantum will
* make htb ignore the r2q for this class. */
if ((class->min_rate / HTB_RATE2QUANTUM) < mtu) {
opt.quantum = mtu;
}
opt.buffer = tc_calc_buffer(opt.rate.rate, mtu, class->burst);
opt.cbuffer = tc_calc_buffer(opt.ceil.rate, mtu, class->burst);
opt.prio = class->priority;