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sch_cake: Make gso-splitting configurable 

This patch makes sch_cake's gso/gro splitting configurable
from userspace.

To disable breaking apart superpackets in sch_cake:

tc qdisc replace dev whatever root cake no-split-gso

to enable:

tc qdisc replace dev whatever root cake split-gso

Signed-off-by: Toke Høiland-Jørgensen <toke@toke.dk>
Signed-off-by: Dave Taht <dave.taht@gmail.com>
Signed-off-by: David Ahern <dsahern@gmail.com>
This commit is contained in:
Toke Høiland-Jørgensen 2018-08-13 13:36:17 +02:00 committed by David Ahern
parent d97e266e5d
commit 23a67b008a
2 changed files with 32 additions and 0 deletions
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23
man/man8/tc-cake.8
View File

@ -73,6 +73,12 @@ TIME |
]
.br
[
.BR split-gso*
|
.BR no-split-gso
]
.br
[
.BR ack-filter
|
.BR ack-filter-aggressive
@ -546,6 +552,23 @@ If you are shaping inbound, and cannot trust the diffserv markings (as is the
case for Comcast Cable, among others), it is best to use a single queue
"besteffort" mode with wash.
.PP
.B split-gso
.br
This option controls whether CAKE will split General Segmentation
Offload (GSO) super-packets into their on-the-wire components and
dequeue them individually.
.br
Super-packets are created by the networking stack to improve efficiency.
However, because they are larger they take longer to dequeue, which
translates to higher latency for competing flows, especially at lower
bandwidths. CAKE defaults to splitting GSO packets to achieve the lowest
possible latency. At link speeds higher than 10 Gbps, setting the
no-split-gso parameter can increase the maximum achievable throughput by
retaining the full GSO packets.
.SH EXAMPLES
# tc qdisc delete root dev eth0
.br

9
tc/q_cake.c
View File

@ -79,6 +79,7 @@ static void explain(void)
" dual-srchost | dual-dsthost | triple-isolate* ]\n"
" [ nat | nonat* ]\n"
" [ wash | nowash* ]\n"
" [ split-gso* | no-split-gso ]\n"
" [ ack-filter | ack-filter-aggressive | no-ack-filter* ]\n"
" [ memlimit LIMIT ]\n"
" [ ptm | atm | noatm* ] [ overhead N | conservative | raw* ]\n"
@ -99,6 +100,7 @@ static int cake_parse_opt(struct qdisc_util *qu, int argc, char **argv,
__u64 bandwidth = 0;
int ack_filter = -1;
struct rtattr *tail;
int split_gso = -1;
int unlimited = 0;
int flowmode = -1;
int autorate = -1;
@ -155,6 +157,10 @@ static int cake_parse_opt(struct qdisc_util *qu, int argc, char **argv,
wash = 0;
} else if (strcmp(*argv, "wash") == 0) {
wash = 1;
} else if (strcmp(*argv, "split-gso") == 0) {
split_gso = 1;
} else if (strcmp(*argv, "no-split-gso") == 0) {
split_gso = 0;
} else if (strcmp(*argv, "flowblind") == 0) {
flowmode = CAKE_FLOW_NONE;
} else if (strcmp(*argv, "srchost") == 0) {
@ -374,6 +380,9 @@ static int cake_parse_opt(struct qdisc_util *qu, int argc, char **argv,
addattr_l(n, 1024, TCA_CAKE_NAT, &nat, sizeof(nat));
if (wash != -1)
addattr_l(n, 1024, TCA_CAKE_WASH, &wash, sizeof(wash));
if (split_gso != -1)
addattr_l(n, 1024, TCA_CAKE_SPLIT_GSO, &split_gso,
sizeof(split_gso));
if (ingress != -1)
addattr_l(n, 1024, TCA_CAKE_INGRESS, &ingress, sizeof(ingress));
if (ack_filter != -1)