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cxgbe(4): Add a hw.cxgbe.starve_fl sysctl that can be used to starve the

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freelists of netmap receive queues.  This is primarily to test various
congestion scenarios in the chip.

Sponsored by:	Chelsio Communications
This commit is contained in:
Navdeep Parhar 2018-06-15 23:42:22 +00:00
parent 61f63f47b3
commit 0afe96c7bf
2 changed files with 24 additions and 4 deletions
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1
sys/dev/cxgbe/adapter.h
View File

@ -682,6 +682,7 @@ struct sge_nm_rxq {
uint32_t fl_db_val;
u_int fl_hwidx:4;
u_int fl_db_saved;
u_int nid; /* netmap ring # for this queue */
/* infrequently used items after this */

19
sys/dev/cxgbe/t4_netmap.c
View File

@ -89,6 +89,10 @@ SYSCTL_INT(_hw_cxgbe, OID_AUTO, nm_holdoff_tmr_idx, CTLFLAG_RWTUN,
static int nm_cong_drop = 1;
TUNABLE_INT("hw.cxgbe.nm_cong_drop", &nm_cong_drop);
int starve_fl = 0;
SYSCTL_INT(_hw_cxgbe, OID_AUTO, starve_fl, CTLFLAG_RWTUN,
&starve_fl, 0, "Don't ring fl db for netmap rx queues.");
static int
alloc_nm_rxq_hwq(struct vi_info *vi, struct sge_nm_rxq *nm_rxq, int cong)
{
@ -806,6 +810,13 @@ cxgbe_netmap_rxsync(struct netmap_kring *kring, int flags)
kring->nr_kflags &= ~NKR_PENDINTR;
}
if (nm_rxq->fl_db_saved > 0 && starve_fl == 0) {
wmb();
t4_write_reg(sc, sc->sge_kdoorbell_reg,
nm_rxq->fl_db_val | V_PIDX(nm_rxq->fl_db_saved));
nm_rxq->fl_db_saved = 0;
}
/* Userspace done with buffers from kring->nr_hwcur to head */
n = head >= kring->nr_hwcur ? head - kring->nr_hwcur :
kring->nkr_num_slots - kring->nr_hwcur + head;
@ -842,8 +853,12 @@ cxgbe_netmap_rxsync(struct netmap_kring *kring, int flags)
}
if (++dbinc == 8 && n >= 32) {
wmb();
if (starve_fl)
nm_rxq->fl_db_saved += dbinc;
else {
t4_write_reg(sc, sc->sge_kdoorbell_reg,
nm_rxq->fl_db_val | V_PIDX(dbinc));
}
dbinc = 0;
}
}
@ -851,10 +866,14 @@ cxgbe_netmap_rxsync(struct netmap_kring *kring, int flags)
if (dbinc > 0) {
wmb();
if (starve_fl)
nm_rxq->fl_db_saved += dbinc;
else {
t4_write_reg(sc, sc->sge_kdoorbell_reg,
nm_rxq->fl_db_val | V_PIDX(dbinc));
}
}
}
return (0);
}