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xlate: Skip recirculation for output and set actions
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Until 8bf009b ("xlate: Always recirculate after an MPLS POP to a
non-MPLS ethertype.") the translation code took some care to only
recirculate as a result of a pop_mpls action if necessary. This was
implemented using per-action checks and resulted in some maintenance
burden.

Unfortunately recirculation is a relatively expensive operation and a
performance degradation of up to 35% has been observed with the above
mentioned patch applied for the arguably common case of:

	pop_mpls,set(l2 field),output

This patch attempts to strike a balance between performance and
maintainability by special casing set and output actions such
that recirculation may be avoided.

This partially reverts the above mentioned commit. In particular most
of the C code outside of do_xlate_actions().

Signed-off-by: Simon Horman <[email protected]>
Acked-by: Jarno Rajahalme <[email protected]>
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shorman-netronome committed May 27, 2016
1 parent 622ad88 commit e12ec36
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Showing 3 changed files with 196 additions and 7 deletions.
122 changes: 121 additions & 1 deletion ofproto/ofproto-dpif-xlate.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -349,6 +349,12 @@ struct xlate_ctx {
struct ofpbuf frozen_actions;
const struct ofpact_controller *pause;

/* True if a packet was but is no longer MPLS (due to an MPLS pop action).
* This is a trigger for recirculation in cases where translating an action
* or looking up a flow requires access to the fields of the packet after
* the MPLS label stack that was originally present. */
bool was_mpls;

/* True if conntrack has been performed on this packet during processing
* on the current bridge. This is used to determine whether conntrack
* state from the datapath should be honored after thawing. */
Expand Down Expand Up @@ -3029,6 +3035,7 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port,
const struct xport *peer = xport->peer;
struct flow old_flow = ctx->xin->flow;
bool old_conntrack = ctx->conntracked;
bool old_was_mpls = ctx->was_mpls;
cls_version_t old_version = ctx->tables_version;
struct ofpbuf old_stack = ctx->stack;
union mf_subvalue new_stack[1024 / sizeof(union mf_subvalue)];
Expand Down Expand Up @@ -3086,6 +3093,10 @@ compose_output_action__(struct xlate_ctx *ctx, ofp_port_t ofp_port,
/* Restore calling bridge's lookup version. */
ctx->tables_version = old_version;

/* The peer bridge popping MPLS should have no effect on the original
* bridge. */
ctx->was_mpls = old_was_mpls;

/* The peer bridge's conntrack execution should have no effect on the
* original bridge. */
ctx->conntracked = old_conntrack;
Expand Down Expand Up @@ -3294,6 +3305,11 @@ static void
xlate_table_action(struct xlate_ctx *ctx, ofp_port_t in_port, uint8_t table_id,
bool may_packet_in, bool honor_table_miss)
{
/* Check if we need to recirculate before matching in a table. */
if (ctx->was_mpls) {
ctx_trigger_freeze(ctx);
return;
}
if (xlate_resubmit_resource_check(ctx)) {
uint8_t old_table_id = ctx->table_id;
struct rule_dpif *rule;
Expand Down Expand Up @@ -3355,6 +3371,7 @@ xlate_group_bucket(struct xlate_ctx *ctx, struct ofputil_bucket *bucket)
struct ofpbuf action_set = ofpbuf_const_initializer(bucket->ofpacts,
bucket->ofpacts_len);
struct flow old_flow = ctx->xin->flow;
bool old_was_mpls = ctx->was_mpls;

ofpacts_execute_action_set(&action_list, &action_set);
ctx->indentation++;
Expand Down Expand Up @@ -3386,6 +3403,10 @@ xlate_group_bucket(struct xlate_ctx *ctx, struct ofputil_bucket *bucket)
* group buckets. */
ctx->xin->flow = old_flow;

/* The group bucket popping MPLS should have no effect after bucket
* execution. */
ctx->was_mpls = old_was_mpls;

/* The fact that the group bucket exits (for any reason) does not mean that
* the translation after the group action should exit. Specifically, if
* the group bucket freezes translation, the actions after the group action
Expand Down Expand Up @@ -3509,6 +3530,13 @@ xlate_select_group(struct xlate_ctx *ctx, struct group_dpif *group)
{
const char *selection_method = group_dpif_get_selection_method(group);

/* Select groups may access flow keys beyond L2 in order to
* select a bucket. Recirculate as appropriate to make this possible.
*/
if (ctx->was_mpls) {
ctx_trigger_freeze(ctx);
}

if (selection_method[0] == '\0') {
xlate_default_select_group(ctx, group);
} else if (!strcasecmp("hash", selection_method)) {
Expand Down Expand Up @@ -3802,7 +3830,7 @@ compose_mpls_pop_action(struct xlate_ctx *ctx, ovs_be16 eth_type)

if (flow_pop_mpls(flow, n, eth_type, ctx->wc)) {
if (!eth_type_mpls(eth_type) && ctx->xbridge->support.odp.recirc) {
ctx_trigger_freeze(ctx);
ctx->was_mpls = true;
}
} else if (n >= FLOW_MAX_MPLS_LABELS) {
if (ctx->xin->packet != NULL) {
Expand Down Expand Up @@ -4477,6 +4505,95 @@ compose_conntrack_action(struct xlate_ctx *ctx, struct ofpact_conntrack *ofc)
}
}

static void
recirc_for_mpls(const struct ofpact *a, struct xlate_ctx *ctx)
{
/* No need to recirculate if already exiting. */
if (ctx->exit) {
return;
}

/* Do not consider recirculating unless the packet was previously MPLS. */
if (!ctx->was_mpls) {
return;
}

/* Special case these actions, only recirculating if necessary.
* This avoids the overhead of recirculation in common use-cases.
*/
switch (a->type) {

/* Output actions do not require recirculation. */
case OFPACT_OUTPUT:
case OFPACT_ENQUEUE:
case OFPACT_OUTPUT_REG:
/* Set actions that don't touch L3+ fields do not require recirculation. */
case OFPACT_SET_VLAN_VID:
case OFPACT_SET_VLAN_PCP:
case OFPACT_SET_ETH_SRC:
case OFPACT_SET_ETH_DST:
case OFPACT_SET_TUNNEL:
case OFPACT_SET_QUEUE:
/* If actions of a group require recirculation that can be detected
* when translating them. */
case OFPACT_GROUP:
return;

/* Set field that don't touch L3+ fields don't require recirculation. */
case OFPACT_SET_FIELD:
if (mf_is_l3_or_higher(ofpact_get_SET_FIELD(a)->field)) {
break;
}
return;

/* For simplicity, recirculate in all other cases. */
case OFPACT_CONTROLLER:
case OFPACT_BUNDLE:
case OFPACT_STRIP_VLAN:
case OFPACT_PUSH_VLAN:
case OFPACT_SET_IPV4_SRC:
case OFPACT_SET_IPV4_DST:
case OFPACT_SET_IP_DSCP:
case OFPACT_SET_IP_ECN:
case OFPACT_SET_IP_TTL:
case OFPACT_SET_L4_SRC_PORT:
case OFPACT_SET_L4_DST_PORT:
case OFPACT_REG_MOVE:
case OFPACT_STACK_PUSH:
case OFPACT_STACK_POP:
case OFPACT_DEC_TTL:
case OFPACT_SET_MPLS_LABEL:
case OFPACT_SET_MPLS_TC:
case OFPACT_SET_MPLS_TTL:
case OFPACT_DEC_MPLS_TTL:
case OFPACT_PUSH_MPLS:
case OFPACT_POP_MPLS:
case OFPACT_POP_QUEUE:
case OFPACT_FIN_TIMEOUT:
case OFPACT_RESUBMIT:
case OFPACT_LEARN:
case OFPACT_CONJUNCTION:
case OFPACT_MULTIPATH:
case OFPACT_NOTE:
case OFPACT_EXIT:
case OFPACT_SAMPLE:
case OFPACT_UNROLL_XLATE:
case OFPACT_CT:
case OFPACT_NAT:
case OFPACT_DEBUG_RECIRC:
case OFPACT_METER:
case OFPACT_CLEAR_ACTIONS:
case OFPACT_WRITE_ACTIONS:
case OFPACT_WRITE_METADATA:
case OFPACT_GOTO_TABLE:
default:
break;
}

/* Recirculate */
ctx_trigger_freeze(ctx);
}

static void
do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
struct xlate_ctx *ctx)
Expand All @@ -4500,6 +4617,8 @@ do_xlate_actions(const struct ofpact *ofpacts, size_t ofpacts_len,
break;
}

recirc_for_mpls(a, ctx);

if (ctx->exit) {
/* Check if need to store the remaining actions for later
* execution. */
Expand Down Expand Up @@ -5151,6 +5270,7 @@ xlate_actions(struct xlate_in *xin, struct xlate_out *xout)
.frozen_actions = OFPBUF_STUB_INITIALIZER(frozen_actions_stub),
.pause = NULL,

.was_mpls = false,
.conntracked = false,

.ct_nat_action = NULL,
Expand Down
78 changes: 74 additions & 4 deletions tests/mpls-xlate.at
View file
Original file line number Diff line number Diff line change
Expand Up @@ -2,36 +2,106 @@ AT_BANNER([mpls-xlate])

AT_SETUP([MPLS xlate action])

OVS_VSWITCHD_START([add-port br0 p0 -- set Interface p0 type=dummy ofport_request=1])
OVS_VSWITCHD_START(
[add-port br0 p0 -- set Interface p0 type=dummy ofport_request=1 -- \
add-port br0 p1 -- set Interface p1 type=patch \
options:peer=p2 ofport_request=2 -- \
add-br br1 -- \
set bridge br1 other-config:hwaddr=aa:66:aa:66:00:00 -- \
set bridge br1 datapath-type=dummy other-config:datapath-id=1234 \
fail-mode=secure -- \
add-port br1 p2 -- set Interface p2 type=patch \
options:peer=p1])

AT_CHECK([ovs-appctl dpif/show], [0], [dnl
dummy@ovs-dummy: hit:0 missed:0
br0:
br0 65534/100: (dummy)
p0 1/1: (dummy)
p1 2/none: (patch: peer=p2)
br1:
br1 65534/101: (dummy)
p2 1/none: (patch: peer=p1)
])

dnl Setup single MPLS tags.
AT_CHECK([ovs-ofctl -O OpenFlow13 add-group br0 group_id=1232,type=select,bucket=output:LOCAL])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-group br0 group_id=1233,type=all,bucket=output:LOCAL])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-group br0 group_id=1234,type=all,bucket=dec_ttl,output:LOCAL])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-flow br0 in_port=local,dl_type=0x0800,action=push_mpls:0x8847,set_field:10-\>mpls_label,output:1])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-flow br0 dl_type=0x8847,in_port=1,mpls_label=20,action=pop_mpls:0x0800,output:LOCAL])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-flow br0 dl_type=0x8847,in_port=1,mpls_label=21,action=pop_mpls:0x0800,dec_ttl,output:LOCAL])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-flow br0 dl_type=0x8847,in_port=1,mpls_label=22,action=pop_mpls:0x0800,group:1232])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-flow br0 dl_type=0x8847,in_port=1,mpls_label=23,action=pop_mpls:0x0800,group:1233])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-flow br0 dl_type=0x8847,in_port=1,mpls_label=24,action=pop_mpls:0x0800,group:1234])
AT_CHECK([ovs-ofctl -O OpenFlow13 add-flow br0 dl_type=0x8847,in_port=1,mpls_label=25,action=pop_mpls:0x0800,output:2])

AT_CHECK([ovs-ofctl -O OpenFlow13 add-flow br1 in_port=1,action=output:LOCAL])



dnl Test MPLS push
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(100),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x0800),ipv4(src=1.1.2.92,dst=1.1.2.88,proto=17,tos=0,ttl=64,frag=no),udp(src=7777,dst=80)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: push_mpls(label=10,tc=0,ttl=64,bos=1,eth_type=0x8847),1
])

dnl Test MPLS pop
dnl Test MPLS pop then output (actions do not trigger reciculation)
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x8847),mpls(label=20,tc=0,ttl=64,bos=1)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: pop_mpls(eth_type=0x800),100
])

dnl Test MPLS pop, dec_ttl, output (actions trigger recirculation)
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x8847),mpls(label=21,tc=0,ttl=64,bos=1)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: pop_mpls(eth_type=0x800),recirc(0x1)
])

AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'recirc_id(1),in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x0800),ipv4(src=1.1.2.92,dst=1.1.2.88,proto=47,tos=0,ttl=64,frag=no)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: set(ipv4(ttl=63)),100
])

dnl Test MPLS pop then select group output (group type triggers recirculation)
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x8847),mpls(label=22,tc=0,ttl=64,bos=1)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: pop_mpls(eth_type=0x800),recirc(0x2)
])

AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'recirc_id(2),in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x0800),ipv4(src=1.1.2.92,dst=1.1.2.88,proto=47,tos=0,ttl=64,frag=no)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: 100
])

dnl Test MPLS pop then all group output (bucket actions do not trigger recirculation)
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x8847),mpls(label=23,tc=0,ttl=64,bos=1)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: pop_mpls(eth_type=0x800),100
])

dnl Test MPLS pop then all group output (bucket actions trigger recirculation)
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x8847),mpls(label=24,tc=0,ttl=64,bos=1)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: pop_mpls(eth_type=0x800),recirc(0x3)
])

AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'recirc_id(3),in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x0800),ipv4(src=1.1.2.92,dst=1.1.2.88,proto=47,tos=0,ttl=64,frag=no)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: set(ipv4(ttl=63)),100
])

dnl Test MPLS pop then all output to patch port
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x8847),mpls(label=25,tc=0,ttl=64,bos=1)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: pop_mpls(eth_type=0x800),recirc(0x4)
])

AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'recirc_id(4),in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x0800),ipv4(src=1.1.2.92,dst=1.1.2.88,proto=47,tos=0,ttl=64,frag=no)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: 101
])

dnl Setup multiple MPLS tags.
AT_CHECK([ovs-ofctl del-flows br0])

Expand All @@ -52,10 +122,10 @@ AT_CHECK([tail -1 stdout], [0],
dnl Double MPLS pop
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x8847),mpls(label=60,tc=0,ttl=64,bos=0,label=50,tc=0,ttl=64,bos=1)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: pop_mpls(eth_type=0x8847),pop_mpls(eth_type=0x800),recirc(0x2)
[Datapath actions: pop_mpls(eth_type=0x8847),pop_mpls(eth_type=0x800),recirc(0x5)
])

AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'recirc_id(2),in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x0800),ipv4(src=1.1.2.92,dst=1.1.2.88,proto=47,tos=0,ttl=64,frag=no)'], [0], [stdout])
AT_CHECK([ovs-appctl ofproto/trace ovs-dummy 'recirc_id(5),in_port(1),eth(src=f8:bc:12:44:34:b6,dst=f8:bc:12:46:58:e0),eth_type(0x0800),ipv4(src=1.1.2.92,dst=1.1.2.88,proto=47,tos=0,ttl=64,frag=no)'], [0], [stdout])
AT_CHECK([tail -1 stdout], [0],
[Datapath actions: set(ipv4(ttl=10)),100
])
Expand Down
3 changes: 1 addition & 2 deletions tests/ofproto-dpif.at
View file
Original file line number Diff line number Diff line change
Expand Up @@ -6415,8 +6415,7 @@ AT_CHECK([ovs-appctl netdev-dummy/receive p1 'in_port(1),eth(src=50:54:00:00:00:
sleep 1
AT_CHECK([filter_flow_install < ovs-vswitchd.log | strip_xout_keep_actions], [0], [dnl
recirc_id=0,mpls,in_port=1,vlan_tci=0x0000,dl_src=50:54:00:00:00:09,mpls_label=11,mpls_tc=3,mpls_ttl=64,mpls_bos=1, actions:push_mpls(label=11,tc=3,ttl=64,bos=0,eth_type=0x8847),2
recirc_id=0,mpls,in_port=1,vlan_tci=0x0000,dl_src=50:54:00:00:00:0b,mpls_bos=1, actions:pop_mpls(eth_type=0x800),recirc(0x1)
recirc_id=0x1,ip,in_port=1,vlan_tci=0x0000,nw_frag=no, actions:2
recirc_id=0,mpls,in_port=1,vlan_tci=0x0000,dl_src=50:54:00:00:00:0b,mpls_bos=1, actions:pop_mpls(eth_type=0x800),2
])
OVS_VSWITCHD_STOP
AT_CLEANUP
Expand Down

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