Author: np
Date: Fri Jun 15 23:42:22 2018
New Revision: 335243
URL: https://svnweb.freebsd.org/changeset/base/335243
Log:
cxgbe(4): Add a hw.cxgbe.starve_fl sysctl that can be used to starve the
freelists of netmap receive queues. This is primarily to test various
congestion scenarios in the chip.
Sponsored by: Chelsio Communications
Modified:
head/sys/dev/cxgbe/adapter.h
head/sys/dev/cxgbe/t4_netmap.c
Modified: head/sys/dev/cxgbe/adapter.h
==============================================================================
--- head/sys/dev/cxgbe/adapter.h Fri Jun 15 21:36:16 2018
(r335242)
+++ head/sys/dev/cxgbe/adapter.h Fri Jun 15 23:42:22 2018
(r335243)
@@ -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 */
Modified: head/sys/dev/cxgbe/t4_netmap.c
==============================================================================
--- head/sys/dev/cxgbe/t4_netmap.c Fri Jun 15 21:36:16 2018
(r335242)
+++ head/sys/dev/cxgbe/t4_netmap.c Fri Jun 15 23:42:22 2018
(r335243)
@@ -89,6 +89,10 @@ SYSCTL_INT(_hw_cxgbe, OID_AUTO, nm_holdoff_tmr_idx, CT
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 fl
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 fl
}
if (++dbinc == 8 && n >= 32) {
wmb();
- t4_write_reg(sc, sc->sge_kdoorbell_reg,
- nm_rxq->fl_db_val | V_PIDX(dbinc));
+ 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;
}
}
@@ -851,8 +866,12 @@ cxgbe_netmap_rxsync(struct netmap_kring *kring, int fl
if (dbinc > 0) {
wmb();
- t4_write_reg(sc, sc->sge_kdoorbell_reg,
- nm_rxq->fl_db_val | V_PIDX(dbinc));
+ 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));
+ }
}
}
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