[hurd] 08/26: commit 042a53a9e437feaf2230dd2cadcecfae9c7bfe05

[Samuel Thibault]

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sthibault pushed a commit to branch dde
in repository hurd.

commit a4f0e9af03f163f2dd59e80c33de8aa3ea8511fd
Author: Eric Dumazet <address@hidden>
Date:   Fri Jun 5 04:04:16 2009 +0000

    commit 042a53a9e437feaf2230dd2cadcecfae9c7bfe05
    
        net: skb_shared_info optimization
    
        skb_dma_unmap() is quite expensive for small packets,
        because we use two different cache lines from skb_shared_info.
    
        One to access nr_frags, one to access dma_maps[0]
    
        Instead of dma_maps being an array of MAX_SKB_FRAGS + 1 elements,
        let dma_head alone in a new dma_head field, close to nr_frags,
        to reduce cache lines misses.
    
        Tested on my dev machine (bnx2 & tg3 adapters), nice speedup !
    
        Signed-off-by: Eric Dumazet <address@hidden>
        Signed-off-by: David S. Miller <address@hidden>
---
 libdde_linux26/contrib/include/linux/skbuff.h |  5 ++++-
 libdde_linux26/contrib/net/core/skb_dma_map.c | 12 ++++++------
 2 files changed, 10 insertions(+), 7 deletions(-)

diff --git a/libdde_linux26/contrib/include/linux/skbuff.h 
b/libdde_linux26/contrib/include/linux/skbuff.h
index a9e9534..6e8450c 100644
--- a/libdde_linux26/contrib/include/linux/skbuff.h
+++ b/libdde_linux26/contrib/include/linux/skbuff.h
@@ -142,6 +142,9 @@ struct skb_shared_info {
        atomic_t        dataref;
        unsigned short  nr_frags;
        unsigned short  gso_size;
+#ifdef CONFIG_HAS_DMA
+       dma_addr_t      dma_head;
+#endif
        /* Warning: this field is not always filled in (UFO)! */
        unsigned short  gso_segs;
        unsigned short  gso_type;
@@ -152,7 +155,7 @@ struct skb_shared_info {
        struct sk_buff  *frag_list;
        skb_frag_t      frags[MAX_SKB_FRAGS];
 #ifdef CONFIG_HAS_DMA
-       dma_addr_t      dma_maps[MAX_SKB_FRAGS + 1];
+       dma_addr_t      dma_maps[MAX_SKB_FRAGS];
 #endif
 };
 
diff --git a/libdde_linux26/contrib/net/core/skb_dma_map.c 
b/libdde_linux26/contrib/net/core/skb_dma_map.c
index 8623492..07d4ac5 100644
--- a/libdde_linux26/contrib/net/core/skb_dma_map.c
+++ b/libdde_linux26/contrib/net/core/skb_dma_map.c
@@ -20,7 +20,7 @@ int skb_dma_map(struct device *dev, struct sk_buff *skb,
        if (dma_mapping_error(dev, map))
                goto out_err;
 
-       sp->dma_maps[0] = map;
+       sp->dma_head = map;
        for (i = 0; i < sp->nr_frags; i++) {
                skb_frag_t *fp = &sp->frags[i];
 
@@ -28,7 +28,7 @@ int skb_dma_map(struct device *dev, struct sk_buff *skb,
                                   fp->size, dir);
                if (dma_mapping_error(dev, map))
                        goto unwind;
-               sp->dma_maps[i + 1] = map;
+               sp->dma_maps[i] = map;
        }
        sp->num_dma_maps = i + 1;
 
@@ -38,10 +38,10 @@ unwind:
        while (--i >= 0) {
                skb_frag_t *fp = &sp->frags[i];
 
-               dma_unmap_page(dev, sp->dma_maps[i + 1],
+               dma_unmap_page(dev, sp->dma_maps[i],
                               fp->size, dir);
        }
-       dma_unmap_single(dev, sp->dma_maps[0],
+       dma_unmap_single(dev, sp->dma_head,
                         skb_headlen(skb), dir);
 out_err:
        return -ENOMEM;
@@ -54,12 +54,12 @@ void skb_dma_unmap(struct device *dev, struct sk_buff *skb,
        struct skb_shared_info *sp = skb_shinfo(skb);
        int i;
 
-       dma_unmap_single(dev, sp->dma_maps[0],
+       dma_unmap_single(dev, sp->dma_head,
                         skb_headlen(skb), dir);
        for (i = 0; i < sp->nr_frags; i++) {
                skb_frag_t *fp = &sp->frags[i];
 
-               dma_unmap_page(dev, sp->dma_maps[i + 1],
+               dma_unmap_page(dev, sp->dma_maps[i],
                               fp->size, dir);
        }
 }

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