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sfxge: add tunables to control LRO parameters on driver load time

Browse Source 
Sponsored by:   Solarflare Communications, Inc.
Approved by:    gnn (mentor)
This commit is contained in:
Andrew Rybchenko 2015-03-17 08:14:46 +00:00
parent 25fd8105c9
commit 245d157651
2 changed files with 61 additions and 0 deletions
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21
share/man/man4/sfxge.4
View File

@ -120,6 +120,27 @@ The value must be greater than or equal to 0.
The maximum number of allocated RSS channels for the Nth adapter.
If set to 0 or unset, the number of channels is determined by the number
of CPU cores.
.It Va hw.sfxge.lro.table_size
Size of the LRO hash table.
Must be a power of 2.
A larger table means we can accelerate a larger number of streams.
.It Va hw.sfxge.lro.chain_max
The maximum length of a hash chain.
If chains get too long then the lookup time increases and may exceed
the benefit of LRO.
.It Va hw.sfxge.lro.idle_ticks
The maximum time (in ticks) that a connection can be idle before it's LRO
state is discarded.
.It Va hw.sfxge.lro.slow_start_packets
Number of packets with payload that must arrive in-order before a connection
is eligible for LRO.
The idea is we should avoid coalescing segments when the sender is in
slow-start because reducing the ACK rate can damage performance.
.It Va hw.sfxge.lro.loss_packets
Number of packets with payload that must arrive in-order following loss
before a connection is eligible for LRO.
The idea is we should avoid coalescing segments when the sender is recovering
from loss, because reducing the ACK rate can damage performance.
.El
.Sh SUPPORT
For general information and support,

40
sys/dev/sfxge/sfxge_rx.c
View File

@ -36,6 +36,7 @@ __FBSDID("$FreeBSD$");
#include <sys/socket.h>
#include <sys/sysctl.h>
#include <sys/limits.h>
#include <sys/syslog.h>
#include <net/ethernet.h>
#include <net/if.h>
@ -58,20 +59,38 @@ __FBSDID("$FreeBSD$");
#ifdef SFXGE_LRO
SYSCTL_NODE(_hw_sfxge, OID_AUTO, lro, CTLFLAG_RD, NULL,
"Large receive offload (LRO) parameters");
#define SFXGE_LRO_PARAM(_param) SFXGE_PARAM(lro._param)
/* Size of the LRO hash table. Must be a power of 2. A larger table
* means we can accelerate a larger number of streams.
*/
static unsigned lro_table_size = 128;
TUNABLE_INT(SFXGE_LRO_PARAM(table_size), &lro_table_size);
SYSCTL_UINT(_hw_sfxge_lro, OID_AUTO, table_size, CTLFLAG_RDTUN,
&lro_table_size, 0,
"Size of the LRO hash table (must be a power of 2)");
/* Maximum length of a hash chain. If chains get too long then the lookup
* time increases and may exceed the benefit of LRO.
*/
static unsigned lro_chain_max = 20;
TUNABLE_INT(SFXGE_LRO_PARAM(chain_max), &lro_chain_max);
SYSCTL_UINT(_hw_sfxge_lro, OID_AUTO, chain_max, CTLFLAG_RDTUN,
&lro_chain_max, 0,
"The maximum length of a hash chain");
/* Maximum time (in ticks) that a connection can be idle before it's LRO
* state is discarded.
*/
static unsigned lro_idle_ticks; /* initialised in sfxge_rx_init() */
TUNABLE_INT(SFXGE_LRO_PARAM(idle_ticks), &lro_idle_ticks);
SYSCTL_UINT(_hw_sfxge_lro, OID_AUTO, idle_ticks, CTLFLAG_RDTUN,
&lro_idle_ticks, 0,
"The maximum time (in ticks) that a connection can be idle "
"before it's LRO state is discarded");
/* Number of packets with payload that must arrive in-order before a
* connection is eligible for LRO. The idea is we should avoid coalescing
@ -79,6 +98,11 @@ static unsigned lro_idle_ticks; /* initialised in sfxge_rx_init() */
* can damage performance.
*/
static int lro_slow_start_packets = 2000;
TUNABLE_INT(SFXGE_LRO_PARAM(slow_start_packets), &lro_slow_start_packets);
SYSCTL_UINT(_hw_sfxge_lro, OID_AUTO, slow_start_packets, CTLFLAG_RDTUN,
&lro_slow_start_packets, 0,
"Number of packets with payload that must arrive in-order before "
"a connection is eligible for LRO");
/* Number of packets with payload that must arrive in-order following loss
* before a connection is eligible for LRO. The idea is we should avoid
@ -86,6 +110,11 @@ static int lro_slow_start_packets = 2000;
* reducing the ACK rate can damage performance.
*/
static int lro_loss_packets = 20;
TUNABLE_INT(SFXGE_LRO_PARAM(loss_packets), &lro_loss_packets);
SYSCTL_UINT(_hw_sfxge_lro, OID_AUTO, loss_packets, CTLFLAG_RDTUN,
&lro_loss_packets, 0,
"Number of packets with payload that must arrive in-order "
"following loss before a connection is eligible for LRO");
/* Flags for sfxge_lro_conn::l2_id; must not collide with EVL_VLID_MASK */
#define SFXGE_LRO_L2_ID_VLAN 0x4000
@ -1239,6 +1268,13 @@ sfxge_rx_init(struct sfxge_softc *sc)
int rc;
#ifdef SFXGE_LRO
if (!ISP2(lro_table_size)) {
log(LOG_ERR, "%s=%u must be power of 2",
SFXGE_LRO_PARAM(table_size), lro_table_size);
rc = EINVAL;
goto fail_lro_table_size;
}
if (lro_idle_ticks == 0)
lro_idle_ticks = hz / 10 + 1; /* 100 ms */
#endif
@ -1266,5 +1302,9 @@ sfxge_rx_init(struct sfxge_softc *sc)
sfxge_rx_qfini(sc, index);
sc->rxq_count = 0;
#ifdef SFXGE_LRO
fail_lro_table_size:
#endif
return (rc);
}