On Tue, 2014-02-11 at 13:28 -0800, Eric Dumazet wrote: [...] > Incoming frames might be taken out of order-3 pages. > > With regular Ethernet frames, this is 21 frames per order-3 pages. > > ACTIVE_PFN_MAX_OVERLAP seems too small. > > Alternative would be to user order-0 only pages if CONFIG_DMA_API_DEBUG > is set. Not sure if it works if PAGE_SIZE=66536 ....
Indeed, you can get a lot of packet buffers into a 64K page... > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > index f589c9af8cbf..1b9995adfd29 100644 > --- a/include/linux/skbuff.h > +++ b/include/linux/skbuff.h > @@ -1924,7 +1924,11 @@ static inline void __skb_queue_purge(struct > sk_buff_head *list) > kfree_skb(skb); > } > > +#if defined(CONFIG_DMA_API_DEBUG) > +#define NETDEV_FRAG_PAGE_MAX_ORDER 0 > +#else > #define NETDEV_FRAG_PAGE_MAX_ORDER get_order(32768) > +#endif > #define NETDEV_FRAG_PAGE_MAX_SIZE (PAGE_SIZE << NETDEV_FRAG_PAGE_MAX_ORDER) > #define NETDEV_PAGECNT_MAX_BIAS NETDEV_FRAG_PAGE_MAX_SIZE > That may be useful for debugging this particular problem, but please don't make debugging options change behaviour like this. Ben. -- Ben Hutchings If more than one person is responsible for a bug, no one is at fault.
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