gro: New frags interface to avoid copying shinfo

It turns out that copying a 16-byte area at ~800k times a second
can be really expensive :) This patch redesigns the frags GRO
interface to avoid copying that area twice.

The two disciples of the frags interface have been converted.

Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/drivers/net/cxgb3/adapter.h b/drivers/net/cxgb3/adapter.h
index 714df2b..322434a 100644 (file)
--- a/drivers/net/cxgb3/adapter.h
+++ b/drivers/net/cxgb3/adapter.h
@@ -195,7 +195,7 @@ struct sge_qset {           /* an SGE queue set */
        struct sge_rspq rspq;
        struct sge_fl fl[SGE_RXQ_PER_SET];
        struct sge_txq txq[SGE_TXQ_PER_SET];
-       struct napi_gro_fraginfo lro_frag_tbl;
+       int nomem;
        int lro_enabled;
        void *lro_va;
        struct net_device *netdev;

diff --git a/drivers/net/cxgb3/sge.c b/drivers/net/cxgb3/sge.c
index 26d3587..73d569e 100644 (file)
--- a/drivers/net/cxgb3/sge.c
+++ b/drivers/net/cxgb3/sge.c
@@ -654,7 +654,8 @@ static void t3_reset_qset(struct sge_qset *q)
        q->txq_stopped = 0;
        q->tx_reclaim_timer.function = NULL; /* for t3_stop_sge_timers() */
        q->rx_reclaim_timer.function = NULL;
-       q->lro_frag_tbl.nr_frags = q->lro_frag_tbl.len = 0;
+       q->nomem = 0;
+       napi_free_frags(&q->napi);
 }
 
 
@@ -2074,20 +2075,19 @@ static void lro_add_page(struct adapter *adap, struct sge_qset *qs,
                         struct sge_fl *fl, int len, int complete)
 {
        struct rx_sw_desc *sd = &fl->sdesc[fl->cidx];
+       struct sk_buff *skb = NULL;
        struct cpl_rx_pkt *cpl;
-       struct skb_frag_struct *rx_frag = qs->lro_frag_tbl.frags;
-       int nr_frags = qs->lro_frag_tbl.nr_frags;
-       int frag_len = qs->lro_frag_tbl.len;
+       struct skb_frag_struct *rx_frag;
+       int nr_frags;
        int offset = 0;
 
-       if (!nr_frags) {
-               offset = 2 + sizeof(struct cpl_rx_pkt);
-               qs->lro_va = cpl = sd->pg_chunk.va + 2;
+       if (!qs->nomem) {
+               skb = napi_get_frags(&qs->napi);
+               qs->nomem = !skb;
        }
 
        fl->credits--;
 
-       len -= offset;
        pci_dma_sync_single_for_cpu(adap->pdev,
                                    pci_unmap_addr(sd, dma_addr),
                                    fl->buf_size - SGE_PG_RSVD,
@@ -2100,21 +2100,38 @@ static void lro_add_page(struct adapter *adap, struct sge_qset *qs,
                               fl->alloc_size,
                               PCI_DMA_FROMDEVICE);
 
+       if (!skb) {
+               put_page(sd->pg_chunk.page);
+               if (complete)
+                       qs->nomem = 0;
+               return;
+       }
+
+       rx_frag = skb_shinfo(skb)->frags;
+       nr_frags = skb_shinfo(skb)->nr_frags;
+
+       if (!nr_frags) {
+               offset = 2 + sizeof(struct cpl_rx_pkt);
+               qs->lro_va = sd->pg_chunk.va + 2;
+       }
+       len -= offset;
+
        prefetch(qs->lro_va);
 
        rx_frag += nr_frags;
        rx_frag->page = sd->pg_chunk.page;
        rx_frag->page_offset = sd->pg_chunk.offset + offset;
        rx_frag->size = len;
-       frag_len += len;
-       qs->lro_frag_tbl.nr_frags++;
-       qs->lro_frag_tbl.len = frag_len;
 
+       skb->len += len;
+       skb->data_len += len;
+       skb->truesize += len;
+       skb_shinfo(skb)->nr_frags++;
 
        if (!complete)
                return;
 
-       qs->lro_frag_tbl.ip_summed = CHECKSUM_UNNECESSARY;
+       skb->ip_summed = CHECKSUM_UNNECESSARY;
        cpl = qs->lro_va;
 
        if (unlikely(cpl->vlan_valid)) {
@@ -2123,15 +2140,11 @@ static void lro_add_page(struct adapter *adap, struct sge_qset *qs,
                struct vlan_group *grp = pi->vlan_grp;
 
                if (likely(grp != NULL)) {
-                       vlan_gro_frags(&qs->napi, grp, ntohs(cpl->vlan),
-                                      &qs->lro_frag_tbl);
-                       goto out;
+                       vlan_gro_frags(&qs->napi, grp, ntohs(cpl->vlan));
+                       return;
                }
        }
-       napi_gro_frags(&qs->napi, &qs->lro_frag_tbl);
-
-out:
-       qs->lro_frag_tbl.nr_frags = qs->lro_frag_tbl.len = 0;
+       napi_gro_frags(&qs->napi);
 }
 
 /**
@@ -2300,8 +2313,6 @@ no_mem:
                        if (fl->use_pages) {
                                void *addr = fl->sdesc[fl->cidx].pg_chunk.va;
 
-                               prefetch(&qs->lro_frag_tbl);
-
                                prefetch(addr);
 #if L1_CACHE_BYTES < 128
                                prefetch(addr + L1_CACHE_BYTES);

diff --git a/drivers/net/sfc/rx.c b/drivers/net/sfc/rx.c
index 66d7fe3..01f9432 100644 (file)
--- a/drivers/net/sfc/rx.c
+++ b/drivers/net/sfc/rx.c
@@ -450,17 +450,27 @@ static void efx_rx_packet_lro(struct efx_channel *channel,
 
        /* Pass the skb/page into the LRO engine */
        if (rx_buf->page) {
-               struct napi_gro_fraginfo info;
+               struct sk_buff *skb = napi_get_frags(napi);
 
-               info.frags[0].page = rx_buf->page;
-               info.frags[0].page_offset = efx_rx_buf_offset(rx_buf);
-               info.frags[0].size = rx_buf->len;
-               info.nr_frags = 1;
-               info.ip_summed = CHECKSUM_UNNECESSARY;
-               info.len = rx_buf->len;
+               if (!skb) {
+                       put_page(rx_buf->page);
+                       goto out;
+               }
+
+               skb_shinfo(skb)->frags[0].page = rx_buf->page;
+               skb_shinfo(skb)->frags[0].page_offset =
+                       efx_rx_buf_offset(rx_buf);
+               skb_shinfo(skb)->frags[0].size = rx_buf->len;
+               skb_shinfo(skb)->nr_frags = 1;
+
+               skb->len = rx_buf->len;
+               skb->data_len = rx_buf->len;
+               skb->truesize += rx_buf->len;
+               skb->ip_summed = CHECKSUM_UNNECESSARY;
 
-               napi_gro_frags(napi, &info);
+               napi_gro_frags(napi);
 
+out:
                EFX_BUG_ON_PARANOID(rx_buf->skb);
                rx_buf->page = NULL;
        } else {

diff --git a/include/linux/if_vlan.h b/include/linux/if_vlan.h
index e1ff5b1..7ff9af1 100644 (file)
--- a/include/linux/if_vlan.h
+++ b/include/linux/if_vlan.h
@@ -118,8 +118,7 @@ extern int vlan_hwaccel_do_receive(struct sk_buff *skb);
 extern int vlan_gro_receive(struct napi_struct *napi, struct vlan_group *grp,
                            unsigned int vlan_tci, struct sk_buff *skb);
 extern int vlan_gro_frags(struct napi_struct *napi, struct vlan_group *grp,
-                         unsigned int vlan_tci,
-                         struct napi_gro_fraginfo *info);
+                         unsigned int vlan_tci);
 
 #else
 static inline struct net_device *vlan_dev_real_dev(const struct net_device *dev)
@@ -154,8 +153,7 @@ static inline int vlan_gro_receive(struct napi_struct *napi,
 }
 
 static inline int vlan_gro_frags(struct napi_struct *napi,
-                                struct vlan_group *grp, unsigned int vlan_tci,
-                                struct napi_gro_fraginfo *info)
+                                struct vlan_group *grp, unsigned int vlan_tci)
 {
        return NET_RX_DROP;
 }

diff --git a/include/linux/netdevice.h b/include/linux/netdevice.h
index 2e7783f..54db3eb 100644 (file)
--- a/include/linux/netdevice.h
+++ b/include/linux/netdevice.h
@@ -1047,14 +1047,6 @@ struct packet_type {
        struct list_head        list;
 };
 
-struct napi_gro_fraginfo {
-       skb_frag_t frags[MAX_SKB_FRAGS];
-       unsigned int nr_frags;
-       unsigned int ip_summed;
-       unsigned int len;
-       __wsum csum;
-};
-
 #include <linux/interrupt.h>
 #include <linux/notifier.h>
 
@@ -1442,12 +1434,18 @@ extern int              napi_gro_receive(struct napi_struct *napi,
                                         struct sk_buff *skb);
 extern void            napi_reuse_skb(struct napi_struct *napi,
                                       struct sk_buff *skb);
-extern struct sk_buff *        napi_fraginfo_skb(struct napi_struct *napi,
-                                         struct napi_gro_fraginfo *info);
+extern struct sk_buff *        napi_get_frags(struct napi_struct *napi);
 extern int             napi_frags_finish(struct napi_struct *napi,
                                          struct sk_buff *skb, int ret);
-extern int             napi_gro_frags(struct napi_struct *napi,
-                                      struct napi_gro_fraginfo *info);
+extern struct sk_buff *        napi_frags_skb(struct napi_struct *napi);
+extern int             napi_gro_frags(struct napi_struct *napi);
+
+static inline void napi_free_frags(struct napi_struct *napi)
+{
+       kfree_skb(napi->skb);
+       napi->skb = NULL;
+}
+
 extern void            netif_nit_deliver(struct sk_buff *skb);
 extern int             dev_valid_name(const char *name);
 extern int             dev_ioctl(struct net *net, unsigned int cmd, void __user *);

diff --git a/net/8021q/vlan_core.c b/net/8021q/vlan_core.c
index 654e45f..c1f51e4 100644 (file)
--- a/net/8021q/vlan_core.c
+++ b/net/8021q/vlan_core.c
@@ -114,9 +114,9 @@ int vlan_gro_receive(struct napi_struct *napi, struct vlan_group *grp,
 EXPORT_SYMBOL(vlan_gro_receive);
 
 int vlan_gro_frags(struct napi_struct *napi, struct vlan_group *grp,
-                  unsigned int vlan_tci, struct napi_gro_fraginfo *info)
+                  unsigned int vlan_tci)
 {
-       struct sk_buff *skb = napi_fraginfo_skb(napi, info);
+       struct sk_buff *skb = napi_frags_skb(napi);
 
        if (!skb)
                return NET_RX_DROP;

diff --git a/net/core/dev.c b/net/core/dev.c
index 91d792d..619fa14 100644 (file)
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -2519,16 +2519,10 @@ void napi_reuse_skb(struct napi_struct *napi, struct sk_buff *skb)
 }
 EXPORT_SYMBOL(napi_reuse_skb);
 
-struct sk_buff *napi_fraginfo_skb(struct napi_struct *napi,
-                                 struct napi_gro_fraginfo *info)
+struct sk_buff *napi_get_frags(struct napi_struct *napi)
 {
        struct net_device *dev = napi->dev;
        struct sk_buff *skb = napi->skb;
-       struct ethhdr *eth;
-       skb_frag_t *frag;
-       int i;
-
-       napi->skb = NULL;
 
        if (!skb) {
                skb = netdev_alloc_skb(dev, GRO_MAX_HEAD + NET_IP_ALIGN);
@@ -2536,47 +2530,14 @@ struct sk_buff *napi_fraginfo_skb(struct napi_struct *napi,
                        goto out;
 
                skb_reserve(skb, NET_IP_ALIGN);
-       }
-
-       BUG_ON(info->nr_frags > MAX_SKB_FRAGS);
-       frag = &info->frags[info->nr_frags - 1];
 
-       for (i = skb_shinfo(skb)->nr_frags; i < info->nr_frags; i++) {
-               skb_fill_page_desc(skb, i, frag->page, frag->page_offset,
-                                  frag->size);
-               frag++;
+               napi->skb = skb;
        }
-       skb_shinfo(skb)->nr_frags = info->nr_frags;
-
-       skb->data_len = info->len;
-       skb->len += info->len;
-       skb->truesize += info->len;
-
-       skb_reset_mac_header(skb);
-       skb_gro_reset_offset(skb);
-
-       eth = skb_gro_header(skb, sizeof(*eth));
-       if (!eth) {
-               napi_reuse_skb(napi, skb);
-               skb = NULL;
-               goto out;
-       }
-
-       skb_gro_pull(skb, sizeof(*eth));
-
-       /*
-        * This works because the only protocols we care about don't require
-        * special handling.  We'll fix it up properly at the end.
-        */
-       skb->protocol = eth->h_proto;
-
-       skb->ip_summed = info->ip_summed;
-       skb->csum = info->csum;
 
 out:
        return skb;
 }
-EXPORT_SYMBOL(napi_fraginfo_skb);
+EXPORT_SYMBOL(napi_get_frags);
 
 int napi_frags_finish(struct napi_struct *napi, struct sk_buff *skb, int ret)
 {
@@ -2606,9 +2567,39 @@ int napi_frags_finish(struct napi_struct *napi, struct sk_buff *skb, int ret)
 }
 EXPORT_SYMBOL(napi_frags_finish);
 
-int napi_gro_frags(struct napi_struct *napi, struct napi_gro_fraginfo *info)
+struct sk_buff *napi_frags_skb(struct napi_struct *napi)
+{
+       struct sk_buff *skb = napi->skb;
+       struct ethhdr *eth;
+
+       napi->skb = NULL;
+
+       skb_reset_mac_header(skb);
+       skb_gro_reset_offset(skb);
+
+       eth = skb_gro_header(skb, sizeof(*eth));
+       if (!eth) {
+               napi_reuse_skb(napi, skb);
+               skb = NULL;
+               goto out;
+       }
+
+       skb_gro_pull(skb, sizeof(*eth));
+
+       /*
+        * This works because the only protocols we care about don't require
+        * special handling.  We'll fix it up properly at the end.
+        */
+       skb->protocol = eth->h_proto;
+
+out:
+       return skb;
+}
+EXPORT_SYMBOL(napi_frags_skb);
+
+int napi_gro_frags(struct napi_struct *napi)
 {
-       struct sk_buff *skb = napi_fraginfo_skb(napi, info);
+       struct sk_buff *skb = napi_frags_skb(napi);
 
        if (!skb)
                return NET_RX_DROP;
@@ -2712,7 +2703,7 @@ void netif_napi_del(struct napi_struct *napi)
        struct sk_buff *skb, *next;
 
        list_del_init(&napi->dev_list);
-       kfree_skb(napi->skb);
+       napi_free_frags(napi);
 
        for (skb = napi->gro_list; skb; skb = next) {
                next = skb->next;