On Mon, Dec 23, 2013 at 09:27:07AM -0800, Eric Dumazet wrote: > On Mon, 2013-12-23 at 16:12 +0800, Jason Wang wrote: > > On 12/17/2013 08:16 AM, Michael Dalton wrote: > > > The virtio-net driver currently uses netdev_alloc_frag() for GFP_ATOMIC > > > mergeable rx buffer allocations. This commit migrates virtio-net to use > > > per-receive queue page frags for GFP_ATOMIC allocation. This change > > > unifies > > > mergeable rx buffer memory allocation, which now will use > > > skb_refill_frag() > > > for both atomic and GFP-WAIT buffer allocations. > > > > > > To address fragmentation concerns, if after buffer allocation there > > > is too little space left in the page frag to allocate a subsequent > > > buffer, the remaining space is added to the current allocated buffer > > > so that the remaining space can be used to store packet data. > > > > > > Signed-off-by: Michael Dalton <[email protected]> > > > --- > > > drivers/net/virtio_net.c | 69 > > > ++++++++++++++++++++++++++---------------------- > > > 1 file changed, 38 insertions(+), 31 deletions(-) > > > > > > diff --git a/drivers/net/virtio_net.c b/drivers/net/virtio_net.c > > > index c51a988..d38d130 100644 > > > --- a/drivers/net/virtio_net.c > > > +++ b/drivers/net/virtio_net.c > > > @@ -78,6 +78,9 @@ struct receive_queue { > > > /* Chain pages by the private ptr. */ > > > struct page *pages; > > > > > > + /* Page frag for GFP_ATOMIC packet buffer allocation. */ > > > + struct page_frag atomic_frag; > > > + > > > /* RX: fragments + linear part + virtio header */ > > > struct scatterlist sg[MAX_SKB_FRAGS + 2]; > > > > > > @@ -127,9 +130,9 @@ struct virtnet_info { > > > struct mutex config_lock; > > > > > > /* Page_frag for GFP_KERNEL packet buffer allocation when we run > > > - * low on memory. > > > + * low on memory. May sleep. > > > */ > > > - struct page_frag alloc_frag; > > > + struct page_frag sleep_frag; > > > > Any reason to use two different page_frag consider only > > skb_page_frag_refill() is used? > > One is used under process context, where preemption and GFP_KERNEL are > allowed.
Yes but it is always used with napi disabled. > One is used from softirq context and GFP_ATOMIC. This one is used only under napi. > You cant share a common > page_frag. So there isn't a conflict with respect to locking. Is it problematic to use same page_frag with both GFP_ATOMIC and with GFP_KERNEL? If yes why? > Acked-by: Eric Dumazet <[email protected]> > > _______________________________________________ Virtualization mailing list [email protected] https://lists.linuxfoundation.org/mailman/listinfo/virtualization
