[src/trunk]: src/sys/dev/ic tighter queue control - according to spec actual ...

[jdolecek <jdolecek%NetBSD.org@localhost>]

details:   https://anonhg.NetBSD.org/src/rev/fc9883175eb0
branches:  trunk
changeset: 348659:fc9883175eb0
user:      jdolecek <jdolecek%NetBSD.org@localhost>
date:      Tue Nov 01 14:24:35 2016 +0000

description:
tighter queue control - according to spec actual cap on number of commands
in flight is actually one less then queue size, head == tail means empty
queue

diffstat:

 sys/dev/ic/nvme.c    |  38 +++++++++++++++++++++++++++-----------
 sys/dev/ic/nvmevar.h |   5 +++--
 2 files changed, 30 insertions(+), 13 deletions(-)

diffs (129 lines):

diff -r 3b631c188fce -r fc9883175eb0 sys/dev/ic/nvme.c
--- a/sys/dev/ic/nvme.c Tue Nov 01 14:21:30 2016 +0000
+++ b/sys/dev/ic/nvme.c Tue Nov 01 14:24:35 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvme.c,v 1.19 2016/10/20 19:20:40 jdolecek Exp $       */
+/*     $NetBSD: nvme.c,v 1.20 2016/11/01 14:24:35 jdolecek Exp $       */
 /*     $OpenBSD: nvme.c,v 1.49 2016/04/18 05:59:50 dlg Exp $ */
 
 /*
@@ -18,7 +18,7 @@
  */
 
 #include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: nvme.c,v 1.19 2016/10/20 19:20:40 jdolecek Exp $");
+__KERNEL_RCSID(0, "$NetBSD: nvme.c,v 1.20 2016/11/01 14:24:35 jdolecek Exp $");
 
 #include <sys/param.h>
 #include <sys/systm.h>
@@ -58,7 +58,7 @@
 static void    nvme_fill_identify(struct nvme_queue *, struct nvme_ccb *,
                    void *);
 
-static int     nvme_ccbs_alloc(struct nvme_queue *, u_int);
+static int     nvme_ccbs_alloc(struct nvme_queue *, uint16_t);
 static void    nvme_ccbs_free(struct nvme_queue *);
 
 static struct nvme_ccb *
@@ -333,8 +333,8 @@
        uint32_t reg;
        u_int dstrd;
        u_int mps = PAGE_SHIFT;
-       int adminq_entries = nvme_adminq_size;
-       int ioq_entries = nvme_ioq_size;
+       uint16_t adminq_entries = nvme_adminq_size;
+       uint16_t ioq_entries = nvme_ioq_size;
        int i;
 
        reg = nvme_read4(sc, NVME_VS);
@@ -1079,7 +1079,8 @@
                        /* NOTREACHED */
                }
 #endif
-               rv = 1;
+
+               rv++;
 
                /*
                 * Unlock the mutex before calling the ccb_done callback
@@ -1098,6 +1099,12 @@
 
        mutex_exit(&q->q_cq_mtx);
 
+       if (rv) {
+               mutex_enter(&q->q_ccb_mtx);
+               q->q_nccbs_avail += rv;
+               mutex_exit(&q->q_ccb_mtx);
+       }
+
        return rv;
 }
 
@@ -1263,7 +1270,7 @@
 }
 
 static int
-nvme_ccbs_alloc(struct nvme_queue *q, u_int nccbs)
+nvme_ccbs_alloc(struct nvme_queue *q, uint16_t nccbs)
 {
        struct nvme_softc *sc = q->q_sc;
        struct nvme_ccb *ccb;
@@ -1279,6 +1286,7 @@
                return 1;
 
        q->q_nccbs = nccbs;
+       q->q_nccbs_avail = nccbs;
        q->q_ccb_prpls = nvme_dmamem_alloc(sc,
            sizeof(*prpl) * sc->sc_max_sgl * nccbs);
 
@@ -1315,11 +1323,14 @@
 static struct nvme_ccb *
 nvme_ccb_get(struct nvme_queue *q)
 {
-       struct nvme_ccb *ccb;
+       struct nvme_ccb *ccb = NULL;
 
        mutex_enter(&q->q_ccb_mtx);
-       ccb = SIMPLEQ_FIRST(&q->q_ccb_list);
-       if (ccb != NULL) {
+       if (q->q_nccbs_avail > 0) {
+               ccb = SIMPLEQ_FIRST(&q->q_ccb_list);
+               KASSERT(ccb != NULL);
+               q->q_nccbs_avail--;
+
                SIMPLEQ_REMOVE_HEAD(&q->q_ccb_list, ccb_entry);
 #ifdef DEBUG
                ccb->ccb_cookie = NULL;
@@ -1397,7 +1408,12 @@
        nvme_dmamem_sync(sc, q->q_sq_dmamem, BUS_DMASYNC_PREWRITE);
        nvme_dmamem_sync(sc, q->q_cq_dmamem, BUS_DMASYNC_PREREAD);
 
-       if (nvme_ccbs_alloc(q, entries) != 0) {
+       /*
+        * Due to definition of full and empty queue (queue is empty
+        * when head == tail, full when tail is one less then head),
+        * we can actually only have (entries - 1) in-flight commands.
+        */
+       if (nvme_ccbs_alloc(q, entries - 1) != 0) {
                aprint_error_dev(sc->sc_dev, "unable to allocate ccbs\n");
                goto free_cq;
        }
diff -r 3b631c188fce -r fc9883175eb0 sys/dev/ic/nvmevar.h
--- a/sys/dev/ic/nvmevar.h      Tue Nov 01 14:21:30 2016 +0000
+++ b/sys/dev/ic/nvmevar.h      Tue Nov 01 14:24:35 2016 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: nvmevar.h,v 1.9 2016/10/20 19:20:40 jdolecek Exp $     */
+/*     $NetBSD: nvmevar.h,v 1.10 2016/11/01 14:24:35 jdolecek Exp $    */
 /*     $OpenBSD: nvmevar.h,v 1.8 2016/04/14 11:18:32 dlg Exp $ */
 
 /*
@@ -86,7 +86,8 @@
        uint16_t                q_cq_phase;
 
        kmutex_t                q_ccb_mtx;
-       u_int                   q_nccbs;
+       uint16_t                q_nccbs;        /* total number of ccbs */
+       uint16_t                q_nccbs_avail;  /* available ccbs */
        struct nvme_ccb         *q_ccbs;
        SIMPLEQ_HEAD(, nvme_ccb) q_ccb_list;
        struct nvme_dmamem      *q_ccb_prpls;