aoe: zero copy write 2 of 2
Ed L. Cashin [Wed, 20 Sep 2006 18:36:49 +0000 (14:36 -0400)]
Avoid memory copy on writes.
(This patch follows patch 4.)

Signed-off-by: "Ed L. Cashin" <ecashin@coraid.com>
Acked-by: Alan Cox <alan@redhat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/block/aoe/aoe.h
drivers/block/aoe/aoecmd.c
drivers/block/aoe/aoedev.c

index 7b11217..b41fdfe 100644 (file)
@@ -84,6 +84,7 @@ enum {
        DEVFL_PAUSE = (1<<5),
        DEVFL_NEWSIZE = (1<<6), /* need to update dev size in block layer */
        DEVFL_MAXBCNT = (1<<7), /* d->maxbcnt is not changeable */
+       DEVFL_KICKME = (1<<8),
 
        BUFFL_FAIL = 1,
 };
index c0bdc1f..9ebc98a 100644 (file)
@@ -120,7 +120,7 @@ aoecmd_ata_rw(struct aoedev *d, struct frame *f)
        h = (struct aoe_hdr *) skb->mac.raw;
        ah = (struct aoe_atahdr *) (h+1);
        skb->len = sizeof *h + sizeof *ah;
-       memset(h, 0, skb->len);
+       memset(h, 0, ETH_ZLEN);
        f->tag = aoehdr_atainit(d, h);
        f->waited = 0;
        f->buf = buf;
@@ -143,8 +143,9 @@ aoecmd_ata_rw(struct aoedev *d, struct frame *f)
                skb_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
                        offset_in_page(f->bufaddr), bcnt);
                ah->aflags |= AOEAFL_WRITE;
+               skb->len += bcnt;
+               skb->data_len = bcnt;
        } else {
-               skb_shinfo(skb)->nr_frags = 0;
                skb->len = ETH_ZLEN;
                writebit = 0;
        }
@@ -167,8 +168,9 @@ aoecmd_ata_rw(struct aoedev *d, struct frame *f)
        }
 
        skb->dev = d->ifp;
-       skb_get(skb);
-       skb->next = NULL;
+       skb = skb_clone(skb, GFP_ATOMIC);
+       if (skb == NULL)
+               return;
        if (d->sendq_hd)
                d->sendq_tl->next = skb;
        else
@@ -224,6 +226,29 @@ aoecmd_cfg_pkts(ushort aoemajor, unsigned char aoeminor, struct sk_buff **tail)
        return sl;
 }
 
+static struct frame *
+freeframe(struct aoedev *d)
+{
+       struct frame *f, *e;
+       int n = 0;
+
+       f = d->frames;
+       e = f + d->nframes;
+       for (; f<e; f++) {
+               if (f->tag != FREETAG)
+                       continue;
+               if (atomic_read(&skb_shinfo(f->skb)->dataref) == 1) {
+                       skb_shinfo(f->skb)->nr_frags = f->skb->data_len = 0;
+                       return f;
+               }
+               n++;
+       }
+       if (n == d->nframes)    /* wait for network layer */
+               d->flags |= DEVFL_KICKME;
+
+       return NULL;
+}
+
 /* enters with d->lock held */
 void
 aoecmd_work(struct aoedev *d)
@@ -239,7 +264,7 @@ aoecmd_work(struct aoedev *d)
        }
 
 loop:
-       f = getframe(d, FREETAG);
+       f = freeframe(d);
        if (f == NULL)
                return;
        if (d->inprocess == NULL) {
@@ -282,20 +307,25 @@ rexmit(struct aoedev *d, struct frame *f)
        n = DEFAULTBCNT / 512;
        if (ah->scnt > n) {
                ah->scnt = n;
-               if (ah->aflags & AOEAFL_WRITE)
+               if (ah->aflags & AOEAFL_WRITE) {
                        skb_fill_page_desc(skb, 0, virt_to_page(f->bufaddr),
                                offset_in_page(f->bufaddr), DEFAULTBCNT);
+                       skb->len = sizeof *h + sizeof *ah + DEFAULTBCNT;
+                       skb->data_len = DEFAULTBCNT;
+               }
                if (++d->lostjumbo > (d->nframes << 1))
                if (d->maxbcnt != DEFAULTBCNT) {
-                       iprintk("too many lost jumbo - using 1KB frames.\n");
+                       iprintk("e%ld.%ld: too many lost jumbo on %s - using 1KB frames.\n",
+                               d->aoemajor, d->aoeminor, d->ifp->name);
                        d->maxbcnt = DEFAULTBCNT;
                        d->flags |= DEVFL_MAXBCNT;
                }
        }
 
        skb->dev = d->ifp;
-       skb_get(skb);
-       skb->next = NULL;
+       skb = skb_clone(skb, GFP_ATOMIC);
+       if (skb == NULL)
+               return;
        if (d->sendq_hd)
                d->sendq_tl->next = skb;
        else
@@ -350,6 +380,10 @@ rexmit_timer(ulong vp)
                        rexmit(d, f);
                }
        }
+       if (d->flags & DEVFL_KICKME) {
+               d->flags &= ~DEVFL_KICKME;
+               aoecmd_work(d);
+       }
 
        sl = d->sendq_hd;
        d->sendq_hd = d->sendq_tl = NULL;
@@ -552,23 +586,27 @@ aoecmd_ata_rsp(struct sk_buff *skb)
                case WIN_WRITE:
                case WIN_WRITE_EXT:
                        if (f->bcnt -= n) {
+                               skb = f->skb;
                                f->bufaddr += n;
                                put_lba(ahout, f->lba += ahout->scnt);
                                n = f->bcnt;
                                if (n > DEFAULTBCNT)
                                        n = DEFAULTBCNT;
                                ahout->scnt = n >> 9;
-                               if (ahout->aflags & AOEAFL_WRITE)
-                                       skb_fill_page_desc(f->skb, 0,
+                               if (ahout->aflags & AOEAFL_WRITE) {
+                                       skb_fill_page_desc(skb, 0,
                                                virt_to_page(f->bufaddr),
                                                offset_in_page(f->bufaddr), n);
+                                       skb->len = sizeof *hout + sizeof *ahout + n;
+                                       skb->data_len = n;
+                               }
                                f->tag = newtag(d);
                                hout->tag = cpu_to_be32(f->tag);
                                skb->dev = d->ifp;
-                               skb_get(f->skb);
-                               f->skb->next = NULL;
+                               skb = skb_clone(skb, GFP_ATOMIC);
                                spin_unlock_irqrestore(&d->lock, flags);
-                               aoenet_xmit(f->skb);
+                               if (skb)
+                                       aoenet_xmit(skb);
                                return;
                        }
                        if (n > DEFAULTBCNT)
@@ -642,7 +680,7 @@ aoecmd_ata_id(struct aoedev *d)
        struct frame *f;
        struct sk_buff *skb;
 
-       f = getframe(d, FREETAG);
+       f = freeframe(d);
        if (f == NULL) {
                eprintk("can't get a frame. This shouldn't happen.\n");
                return NULL;
@@ -652,8 +690,8 @@ aoecmd_ata_id(struct aoedev *d)
        skb = f->skb;
        h = (struct aoe_hdr *) skb->mac.raw;
        ah = (struct aoe_atahdr *) (h+1);
-       skb->len = sizeof *h + sizeof *ah;
-       memset(h, 0, skb->len);
+       skb->len = ETH_ZLEN;
+       memset(h, 0, ETH_ZLEN);
        f->tag = aoehdr_atainit(d, h);
        f->waited = 0;
 
@@ -663,12 +701,11 @@ aoecmd_ata_id(struct aoedev *d)
        ah->lba3 = 0xa0;
 
        skb->dev = d->ifp;
-       skb_get(skb);
 
        d->rttavg = MAXTIMER;
        d->timer.function = rexmit_timer;
 
-       return skb;
+       return skb_clone(skb, GFP_ATOMIC);
 }
  
 void
@@ -724,7 +761,12 @@ aoecmd_cfg_rsp(struct sk_buff *skb)
                n /= 512;
                if (n > ch->scnt)
                        n = ch->scnt;
-               d->maxbcnt = n ? n * 512 : DEFAULTBCNT;
+               n = n ? n * 512 : DEFAULTBCNT;
+               if (n != d->maxbcnt) {
+                       iprintk("e%ld.%ld: setting %d byte data frames on %s\n",
+                               d->aoemajor, d->aoeminor, n, d->ifp->name);
+                       d->maxbcnt = n;
+               }
        }
 
        /* don't change users' perspective */
index f51d87b..7fd63d4 100644 (file)
@@ -121,6 +121,7 @@ aoedev_downdev(struct aoedev *d)
                        mempool_free(buf, d->bufpool);
                        bio_endio(bio, bio->bi_size, -EIO);
                }
+               skb_shinfo(f->skb)->nr_frags = f->skb->data_len = 0;
        }
        d->inprocess = NULL;