From 025be81e83043f20538dcced1e12c5f8d152fbdb Mon Sep 17 00:00:00 2001 From: Anton Blanchard Date: Fri, 31 Mar 2006 02:27:06 -0800 Subject: [NET]: Allow skb headroom to be overridden Previously we added NET_IP_ALIGN so an architecture can override the padding done to align headers. The next step is to allow the skb headroom to be overridden. We currently always reserve 16 bytes to grow into, meaning all DMAs start 16 bytes into a cacheline. On ppc64 we really want DMA writes to start on a cacheline boundary, so we increase that headroom to one cacheline. Signed-off-by: Anton Blanchard Signed-off-by: David S. Miller --- include/asm-powerpc/system.h | 5 ++++- 1 file changed, 4 insertions(+), 1 deletion(-) (limited to 'include/asm-powerpc') diff --git a/include/asm-powerpc/system.h b/include/asm-powerpc/system.h index 65f5a7b2646b..d075725bf444 100644 --- a/include/asm-powerpc/system.h +++ b/include/asm-powerpc/system.h @@ -365,8 +365,11 @@ __cmpxchg(volatile void *ptr, unsigned long old, unsigned long new, * powers of 2 writes until it reaches sufficient alignment). * * Based on this we disable the IP header alignment in network drivers. + * We also modify NET_SKB_PAD to be a cacheline in size, thus maintaining + * cacheline alignment of buffers. */ -#define NET_IP_ALIGN 0 +#define NET_IP_ALIGN 0 +#define NET_SKB_PAD L1_CACHE_BYTES #endif #define arch_align_stack(x) (x) -- cgit v1.2.3