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[hermon] Limit link poll frequency in DOWN state 

Some older versions of the hardware (and/or firmware) do not report an
event when an Infiniband link reaches the INIT state.  The driver
works around this missing event by calling ib_smc_update() on each
event queue poll while the link is in the DOWN state.

Commit 6cb12ee ("[hermon] Increase polling rate for command
completions") addressed this by speeding up the time taken to issue
each command invoked by ib_smc_update().  Experimentation shows that
the impact is still significant: for example, in a situation where an
unplugged port is opened, the throughput on the other port can be
reduced by over 99%.

Fix by throttling the rate at which link polling is attempted.

Debugged-by: Christian Iversen <ci@iversenit.dk>
Signed-off-by: Michael Brown <mcb30@ipxe.org>
pull/242/head
Michael Brown 2021-01-31 23:29:45 +00:00
parent ba20ba4273
commit def46cf344
2 changed files with 17 additions and 1 deletions
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9
src/drivers/infiniband/hermon.c
View File

@ -2130,6 +2130,8 @@ static void hermon_poll_eq ( struct ib_device *ibdev ) {
struct hermon_event_queue *hermon_eq = &hermon->eq; struct hermon_event_queue *hermon_eq = &hermon->eq;
union hermonprm_event_entry *eqe; union hermonprm_event_entry *eqe;
union hermonprm_doorbell_register db_reg; union hermonprm_doorbell_register db_reg;
unsigned long now;
unsigned long elapsed;
unsigned int eqe_idx_mask; unsigned int eqe_idx_mask;
unsigned int event_type; unsigned int event_type;
@ -2138,7 +2140,12 @@ static void hermon_poll_eq ( struct ib_device *ibdev ) {
*/ */
if ( ib_is_open ( ibdev ) && if ( ib_is_open ( ibdev ) &&
( ibdev->port_state == IB_PORT_STATE_DOWN ) ) { ( ibdev->port_state == IB_PORT_STATE_DOWN ) ) {
ib_smc_update ( ibdev, hermon_mad ); now = currticks();
elapsed = ( now - hermon->last_poll );
if ( elapsed >= HERMON_LINK_POLL_INTERVAL ) {
hermon->last_poll = now;
ib_smc_update ( ibdev, hermon_mad );
}
} }
/* Poll event queue */ /* Poll event queue */

9
src/drivers/infiniband/hermon.h
View File

@ -894,6 +894,8 @@ struct hermon {
/** Event queue */ /** Event queue */
struct hermon_event_queue eq; struct hermon_event_queue eq;
/** Last unsolicited link state poll */
unsigned long last_poll;
/** Unrestricted LKey /** Unrestricted LKey
* *
* Used to get unrestricted memory access. * Used to get unrestricted memory access.
@ -930,6 +932,13 @@ struct hermon {
/** Memory key prefix */ /** Memory key prefix */
#define HERMON_MKEY_PREFIX 0x77000000UL #define HERMON_MKEY_PREFIX 0x77000000UL
/** Link poll interval
*
* Used when we need to poll for link state (rather than relying upon
* receiving an event).
*/
#define HERMON_LINK_POLL_INTERVAL ( TICKS_PER_SEC / 2 )
/* /*
* HCA commands * HCA commands
* *