virtio: Do LIFO in the freelist

Use a SLIST instead of a SIMPLEQ and use LIFO instead of FIFO. This should
improve cache usage.

diff --git a/sys/dev/pv/virtio.c b/sys/dev/pv/virtio.c
index cddeb9d..8d1fb46 100644 (file)
--- a/sys/dev/pv/virtio.c
+++ b/sys/dev/pv/virtio.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: virtio.c,v 1.5 2017/05/27 10:24:31 sf Exp $   */
+/*     $OpenBSD: virtio.c,v 1.6 2017/05/30 08:35:32 sf Exp $   */
 /*     $NetBSD: virtio.c,v 1.3 2011/11/02 23:05:52 njoly Exp $ */
 
 /*
@@ -256,10 +256,10 @@ virtio_init_vq(struct virtio_softc *sc, struct virtqueue *vq, int reinit)
        }
 
        /* free slot management */
-       SIMPLEQ_INIT(&vq->vq_freelist);
+       SLIST_INIT(&vq->vq_freelist);
        for (i = 0; i < vq_size; i++) {
-               SIMPLEQ_INSERT_TAIL(&vq->vq_freelist,
-                                   &vq->vq_entries[i], qe_list);
+               SLIST_INSERT_HEAD(&vq->vq_freelist, &vq->vq_entries[i],
+                   qe_list);
                vq->vq_entries[i].qe_index = i;
        }
 
@@ -405,7 +405,7 @@ virtio_free_vq(struct virtio_softc *sc, struct virtqueue *vq)
 
        /* device must be already deactivated */
        /* confirm the vq is empty */
-       SIMPLEQ_FOREACH(qe, &vq->vq_freelist, qe_list) {
+       SLIST_FOREACH(qe, &vq->vq_freelist, qe_list) {
                i++;
        }
        if (i != vq->vq_num) {
@@ -435,10 +435,10 @@ vq_alloc_entry(struct virtqueue *vq)
 {
        struct vq_entry *qe;
 
-       if (SIMPLEQ_EMPTY(&vq->vq_freelist))
+       if (SLIST_EMPTY(&vq->vq_freelist))
                return NULL;
-       qe = SIMPLEQ_FIRST(&vq->vq_freelist);
-       SIMPLEQ_REMOVE_HEAD(&vq->vq_freelist, qe_list);
+       qe = SLIST_FIRST(&vq->vq_freelist);
+       SLIST_REMOVE_HEAD(&vq->vq_freelist, qe_list);
 
        return qe;
 }
@@ -446,7 +446,7 @@ vq_alloc_entry(struct virtqueue *vq)
 void
 vq_free_entry(struct virtqueue *vq, struct vq_entry *qe)
 {
-       SIMPLEQ_INSERT_TAIL(&vq->vq_freelist, qe, qe_list);
+       SLIST_INSERT_HEAD(&vq->vq_freelist, qe, qe_list);
 }
 
 /*

diff --git a/sys/dev/pv/virtiovar.h b/sys/dev/pv/virtiovar.h
index 5211670..9e453a1 100644 (file)
--- a/sys/dev/pv/virtiovar.h
+++ b/sys/dev/pv/virtiovar.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: virtiovar.h,v 1.3 2017/05/27 10:24:31 sf Exp $        */
+/*     $OpenBSD: virtiovar.h,v 1.4 2017/05/30 08:35:32 sf Exp $        */
 /*     $NetBSD: virtiovar.h,v 1.1 2011/10/30 12:12:21 hannken Exp $    */
 
 /*
@@ -81,7 +81,7 @@
 #endif
 
 struct vq_entry {
-       SIMPLEQ_ENTRY(vq_entry) qe_list; /* free list */
+       SLIST_ENTRY(vq_entry)   qe_list; /* free list */
        uint16_t                qe_index; /* index in vq_desc array */
        /* followings are used only when it is the `head' entry */
        int16_t                 qe_next;     /* next enq slot */
@@ -114,7 +114,7 @@ struct virtqueue {
 
        /* free entry management */
        struct vq_entry         *vq_entries;
-       SIMPLEQ_HEAD(, vq_entry) vq_freelist;
+       SLIST_HEAD(, vq_entry) vq_freelist;
        struct mutex            *vq_freelist_lock;
 
        /* enqueue/dequeue status */