Author: np
Date: Thu Aug 23 16:24:27 2018
New Revision: 338254
URL: https://svnweb.freebsd.org/changeset/base/338254
Log:
cxgbe(4): Use fcmpset instead of cmpset when appropriate.
Suggested by: mjg@
MFC after: 1 month
Sponsored by: Chelsio Communications
Modified:
head/sys/dev/cxgbe/t4_mp_ring.c
Modified: head/sys/dev/cxgbe/t4_mp_ring.c
==============================================================================
--- head/sys/dev/cxgbe/t4_mp_ring.c Thu Aug 23 16:10:28 2018
(r338253)
+++ head/sys/dev/cxgbe/t4_mp_ring.c Thu Aug 23 16:24:27 2018
(r338254)
@@ -122,11 +122,12 @@ drain_ring(struct mp_ring *r, union ring_state os, uin
n = r->drain(r, cidx, pidx);
if (n == 0) {
critical_enter();
+ os.state = r->state;
do {
- os.state = ns.state = r->state;
+ ns.state = os.state;
ns.cidx = cidx;
ns.flags = STALLED;
- } while (atomic_cmpset_64(&r->state, os.state,
+ } while (atomic_fcmpset_64(&r->state, &os.state,
ns.state) == 0);
critical_exit();
if (prev != STALLED)
@@ -149,11 +150,12 @@ drain_ring(struct mp_ring *r, union ring_state os, uin
if (cidx != pidx && pending < 64 && total < budget)
continue;
critical_enter();
+ os.state = r->state;
do {
- os.state = ns.state = r->state;
+ ns.state = os.state;
ns.cidx = cidx;
ns.flags = state_to_flags(ns, total >= budget);
- } while (atomic_cmpset_acq_64(&r->state, os.state, ns.state) ==
0);
+ } while (atomic_fcmpset_acq_64(&r->state, &os.state, ns.state)
== 0);
critical_exit();
if (ns.flags == ABDICATED)
@@ -259,8 +261,8 @@ mp_ring_enqueue(struct mp_ring *r, void **items, int n
* Reserve room for the new items. Our reservation, if successful, is
* from 'pidx_start' to 'pidx_stop'.
*/
+ os.state = r->state;
for (;;) {
- os.state = r->state;
if (n >= space_available(r, os)) {
counter_u64_add(r->drops, n);
MPASS(os.flags != IDLE);
@@ -271,7 +273,7 @@ mp_ring_enqueue(struct mp_ring *r, void **items, int n
ns.state = os.state;
ns.pidx_head = increment_idx(r, os.pidx_head, n);
critical_enter();
- if (atomic_cmpset_64(&r->state, os.state, ns.state))
+ if (atomic_fcmpset_64(&r->state, &os.state, ns.state))
break;
critical_exit();
cpu_spinwait();
@@ -301,11 +303,12 @@ mp_ring_enqueue(struct mp_ring *r, void **items, int n
* Update the ring's pidx_tail. The release style atomic guarantees
* that the items are visible to any thread that sees the updated pidx.
*/
+ os.state = r->state;
do {
- os.state = ns.state = r->state;
+ ns.state = os.state;
ns.pidx_tail = pidx_stop;
ns.flags = BUSY;
- } while (atomic_cmpset_rel_64(&r->state, os.state, ns.state) == 0);
+ } while (atomic_fcmpset_rel_64(&r->state, &os.state, ns.state) == 0);
critical_exit();
counter_u64_add(r->enqueues, n);
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