Skip to content

Commit

Permalink
dpif-netdev: Delay packets' metadata initialization.
Browse files Browse the repository at this point in the history 
When a group of packets arrives from a port, we loop through them to
initialize metadata and then we loop through them again to extract the
flow and perform the exact match classification.

This commit combines the two loops into one, and initializes packet->md
in emc_processing() to improve performance.

Since emc_processing() might also be called after recirculation (in
which case the metadata is already valid), an extra parameter is added
to support both cases.

This commits also implements simple prefetching of packet metadata,
to further improve performance.

Signed-off-by: Daniele Di Proietto <[email protected]>
Acked-by: Andy Zhou <[email protected]>
Acked-by: Chandran, Sugesh <[email protected]>
  • Loading branch information
@ddiproietto
ddiproietto committed Feb 3, 2016
1 parent 34c3c2b commit a90ed02
Show file tree
Hide file tree
Showing 2 changed files with 52 additions and 17 deletions.
61 changes: 44 additions & 17 deletions lib/dpif-netdev.c
View file
Original file line number Diff line number Diff line change
Expand Up @@ -478,7 +478,9 @@ static void dp_netdev_execute_actions(struct dp_netdev_pmd_thread *pmd,
const struct nlattr *actions,
size_t actions_len);
static void dp_netdev_input(struct dp_netdev_pmd_thread *,
struct dp_packet **, int cnt);
struct dp_packet **, int cnt, odp_port_t port_no);
static void dp_netdev_recirculate(struct dp_netdev_pmd_thread *,
struct dp_packet **, int cnt);

static void dp_netdev_disable_upcall(struct dp_netdev *);
static void dp_netdev_pmd_reload_done(struct dp_netdev_pmd_thread *pmd);
Expand Down Expand Up @@ -2555,16 +2557,10 @@ dp_netdev_process_rxq_port(struct dp_netdev_pmd_thread *pmd,
error = netdev_rxq_recv(rxq, packets, &cnt);
cycles_count_end(pmd, PMD_CYCLES_POLLING);
if (!error) {
int i;

*recirc_depth_get() = 0;

/* XXX: initialize md in netdev implementation. */
for (i = 0; i < cnt; i++) {
pkt_metadata_init(&packets[i]->md, port->port_no);
}
cycles_count_start(pmd);
dp_netdev_input(pmd, packets, cnt);
dp_netdev_input(pmd, packets, cnt, port->port_no);
cycles_count_end(pmd, PMD_CYCLES_PROCESSING);
} else if (error != EAGAIN && error != EOPNOTSUPP) {
static struct vlog_rate_limit rl = VLOG_RATE_LIMIT_INIT(1, 5);
Expand Down Expand Up @@ -3284,17 +3280,21 @@ dp_netdev_queue_batches(struct dp_packet *pkt,
}

/* Try to process all ('cnt') the 'packets' using only the exact match cache
* 'flow_cache'. If a flow is not found for a packet 'packets[i]', the
* 'pmd->flow_cache'. If a flow is not found for a packet 'packets[i]', the
* miniflow is copied into 'keys' and the packet pointer is moved at the
* beginning of the 'packets' array.
*
* The function returns the number of packets that needs to be processed in the
* 'packets' array (they have been moved to the beginning of the vector).
*
* If 'md_is_valid' is false, the metadata in 'packets' is not valid and must be
* initialized by this function using 'port_no'.
*/
static inline size_t
emc_processing(struct dp_netdev_pmd_thread *pmd, struct dp_packet **packets,
size_t cnt, struct netdev_flow_key *keys,
struct packet_batch batches[], size_t *n_batches)
struct packet_batch batches[], size_t *n_batches,
bool md_is_valid, odp_port_t port_no)
{
struct emc_cache *flow_cache = &pmd->flow_cache;
struct netdev_flow_key *key = &keys[0];
Expand All @@ -3311,10 +3311,14 @@ emc_processing(struct dp_netdev_pmd_thread *pmd, struct dp_packet **packets,
}

if (i != cnt - 1) {
/* Prefetch next packet data */
/* Prefetch next packet data and metadata. */
OVS_PREFETCH(dp_packet_data(packets[i+1]));
pkt_metadata_prefetch_init(&packets[i+1]->md);
}

if (!md_is_valid) {
pkt_metadata_init(&packet->md, port_no);
}
miniflow_extract(packet, &key->mf);
key->len = 0; /* Not computed yet. */
key->hash = dpif_netdev_packet_get_rss_hash(packet, &key->mf);
Expand Down Expand Up @@ -3475,9 +3479,16 @@ fast_path_processing(struct dp_netdev_pmd_thread *pmd,
dp_netdev_count_packet(pmd, DP_STAT_LOST, lost_cnt);
}

/* Packets enter the datapath from a port (or from recirculation) here.
*
* For performance reasons a caller may choose not to initialize the metadata
* in 'packets': in this case 'mdinit' is false and this function needs to
* initialize it using 'port_no'. If the metadata in 'packets' is already
* valid, 'md_is_valid' must be true and 'port_no' will be ignored. */
static void
dp_netdev_input(struct dp_netdev_pmd_thread *pmd,
struct dp_packet **packets, int cnt)
dp_netdev_input__(struct dp_netdev_pmd_thread *pmd,
struct dp_packet **packets, int cnt,
bool md_is_valid, odp_port_t port_no)
{
#if !defined(__CHECKER__) && !defined(_WIN32)
const size_t PKT_ARRAY_SIZE = cnt;
Expand All @@ -3491,7 +3502,8 @@ dp_netdev_input(struct dp_netdev_pmd_thread *pmd,
size_t newcnt, n_batches, i;

n_batches = 0;
newcnt = emc_processing(pmd, packets, cnt, keys, batches, &n_batches);
newcnt = emc_processing(pmd, packets, cnt, keys, batches, &n_batches,
md_is_valid, port_no);
if (OVS_UNLIKELY(newcnt)) {
fast_path_processing(pmd, packets, newcnt, keys, batches, &n_batches);
}
Expand All @@ -3505,6 +3517,21 @@ dp_netdev_input(struct dp_netdev_pmd_thread *pmd,
}
}

static void
dp_netdev_input(struct dp_netdev_pmd_thread *pmd,
struct dp_packet **packets, int cnt,
odp_port_t port_no)
{
dp_netdev_input__(pmd, packets, cnt, false, port_no);
}

static void
dp_netdev_recirculate(struct dp_netdev_pmd_thread *pmd,
struct dp_packet **packets, int cnt)
{
dp_netdev_input__(pmd, packets, cnt, true, 0);
}

struct dp_netdev_execute_aux {
struct dp_netdev_pmd_thread *pmd;
};
Expand Down Expand Up @@ -3608,7 +3635,7 @@ dp_execute_cb(void *aux_, struct dp_packet **packets, int cnt,
err = push_tnl_action(dp, a, packets, cnt);
if (!err) {
(*depth)++;
dp_netdev_input(pmd, packets, cnt);
dp_netdev_recirculate(pmd, packets, cnt);
(*depth)--;
} else {
dp_netdev_drop_packets(tnl_pkt, cnt, !may_steal);
Expand Down Expand Up @@ -3639,7 +3666,7 @@ dp_execute_cb(void *aux_, struct dp_packet **packets, int cnt,
}

(*depth)++;
dp_netdev_input(pmd, packets, cnt);
dp_netdev_recirculate(pmd, packets, cnt);
(*depth)--;
} else {
dp_netdev_drop_packets(tnl_pkt, cnt, !may_steal);
Expand Down Expand Up @@ -3697,7 +3724,7 @@ dp_execute_cb(void *aux_, struct dp_packet **packets, int cnt,
}

(*depth)++;
dp_netdev_input(pmd, packets, cnt);
dp_netdev_recirculate(pmd, packets, cnt);
(*depth)--;

return;
Expand Down
8 changes: 8 additions & 0 deletions lib/packets.h
View file
Original file line number Diff line number Diff line change
Expand Up @@ -163,6 +163,14 @@ pkt_metadata_init(struct pkt_metadata *md, odp_port_t port)
md->in_port.odp_port = port;
}

/* This function prefetches the cachelines touched by pkt_metadata_init()
* For performance reasons the two functions should be kept in sync. */
static inline void
pkt_metadata_prefetch_init(struct pkt_metadata *md)
{
ovs_prefetch_range(md, offsetof(struct pkt_metadata, tunnel.ip_src));
}

bool dpid_from_string(const char *s, uint64_t *dpidp);

#define ETH_ADDR_LEN 6
Expand Down

0 comments on commit a90ed02

Please sign in to comment.