> If true, I'd like to see some performance numbers please. The numbers have been obtained by running iperf between 2 QEMU Win2012 VMs, 4 vCPU/ 4GB RAM each. iperf parameters: -w 256K -l 256K -t 300 Original kernel 3.15.0-rc5: 34.4 Gbytes transferred, 984 Mbits/sec bandwidth. Kernel 3.15.0-rc5 with our patch: 42.5 Gbytes transferred, 1.22 Gbits/sec bandwidth.
Overall improvement is about 24%. Below are raw iperf outputs. kernel 3.15.0-rc5: C:\iperf>iperf -c 192.168.11.2 -w 256K -l 256K -t 300 ------------------------------------------------------------ Client connecting to 192.168.11.2, TCP port 5001 TCP window size: 256 KByte ------------------------------------------------------------ [ 3] local 192.168.11.1 port 49167 connected with 192.168.11.2 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-300.7 sec 34.4 GBytes 984 Mbits/sec kernel 3.15.0-rc5-patched: C:\iperf>iperf -c 192.168.11.2 -w 256K -l 256K -t 300 ------------------------------------------------------------ Client connecting to 192.168.11.2, TCP port 5001 TCP window size: 256 KByte ------------------------------------------------------------ [ 3] local 192.168.11.1 port 49167 connected with 192.168.11.2 port 5001 [ ID] Interval Transfer Bandwidth [ 3] 0.0-300.7 sec 42.5 GBytes 1.22 Gbits/sec On Tue, May 20, 2014 at 2:50 PM, Michael S. Tsirkin <[email protected]> wrote: > > On Tue, May 20, 2014 at 02:24:21PM +0300, Igor Royzis wrote: > > Fix accessing GSO fragments memory (and a possible corruption therefore) > > after > > reporting completion in a zero copy callback. The previous fix in the > > commit 1fd819ec > > orphaned frags which eliminates zero copy advantages. The fix makes the > > completion > > called after all the fragments were processed avoiding unnecessary > > orphaning/copying > > from userspace. > > > > The GSO fragments corruption issue was observed in a typical QEMU/KVM VM > > setup that > > hosts a Windows guest (since QEMU virtio-net Windows driver doesn't support > > GRO). > > The fix has been verified by running the HCK OffloadLSO test. > > > > Signed-off-by: Igor Royzis <[email protected]> > > Signed-off-by: Anton Nayshtut <[email protected]> > > OK but with 1fd819ec there's no corruption, correct? > So this patch is in fact an optimization? > If true, I'd like to see some performance numbers please. > > Thanks! > > > --- > > include/linux/skbuff.h | 1 + > > net/core/skbuff.c | 18 +++++++++++++----- > > 2 files changed, 14 insertions(+), 5 deletions(-) > > > > diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h > > index 08074a8..8c49edc 100644 > > --- a/include/linux/skbuff.h > > +++ b/include/linux/skbuff.h > > @@ -287,6 +287,7 @@ struct skb_shared_info { > > struct sk_buff *frag_list; > > struct skb_shared_hwtstamps hwtstamps; > > __be32 ip6_frag_id; > > + struct sk_buff *zcopy_src; > > > > /* > > * Warning : all fields before dataref are cleared in __alloc_skb() > > diff --git a/net/core/skbuff.c b/net/core/skbuff.c > > index 1b62343..6fa6342 100644 > > --- a/net/core/skbuff.c > > +++ b/net/core/skbuff.c > > @@ -610,14 +610,18 @@ EXPORT_SYMBOL(__kfree_skb); > > */ > > void kfree_skb(struct sk_buff *skb) > > { > > + struct sk_buff *zcopy_src; > > if (unlikely(!skb)) > > return; > > if (likely(atomic_read(&skb->users) == 1)) > > smp_rmb(); > > else if (likely(!atomic_dec_and_test(&skb->users))) > > return; > > + zcopy_src = skb_shinfo(skb)->zcopy_src; > > trace_kfree_skb(skb, __builtin_return_address(0)); > > __kfree_skb(skb); > > + if (unlikely(zcopy_src)) > > + kfree_skb(zcopy_src); > > } > > EXPORT_SYMBOL(kfree_skb); > > > > @@ -662,14 +666,18 @@ EXPORT_SYMBOL(skb_tx_error); > > */ > > void consume_skb(struct sk_buff *skb) > > { > > + struct sk_buff *zcopy_src; > > if (unlikely(!skb)) > > return; > > if (likely(atomic_read(&skb->users) == 1)) > > smp_rmb(); > > else if (likely(!atomic_dec_and_test(&skb->users))) > > return; > > + zcopy_src = skb_shinfo(skb)->zcopy_src; > > trace_consume_skb(skb); > > __kfree_skb(skb); > > + if (unlikely(zcopy_src)) > > + consume_skb(zcopy_src); > > } > > EXPORT_SYMBOL(consume_skb); > > > > @@ -2867,7 +2875,6 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, > > skb_frag_t *frag = skb_shinfo(head_skb)->frags; > > unsigned int mss = skb_shinfo(head_skb)->gso_size; > > unsigned int doffset = head_skb->data - skb_mac_header(head_skb); > > - struct sk_buff *frag_skb = head_skb; > > unsigned int offset = doffset; > > unsigned int tnl_hlen = skb_tnl_header_len(head_skb); > > unsigned int headroom; > > @@ -2913,7 +2920,6 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, > > i = 0; > > nfrags = skb_shinfo(list_skb)->nr_frags; > > frag = skb_shinfo(list_skb)->frags; > > - frag_skb = list_skb; > > pos += skb_headlen(list_skb); > > > > while (pos < offset + len) { > > @@ -2975,6 +2981,11 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, > > nskb->data - tnl_hlen, > > doffset + tnl_hlen); > > > > + if (skb_shinfo(head_skb)->tx_flags & SKBTX_DEV_ZEROCOPY) { > > + skb_shinfo(nskb)->zcopy_src = head_skb; > > + atomic_inc(&head_skb->users); > > + } > > + > > if (nskb->len == len + doffset) > > goto perform_csum_check; > > > > @@ -3001,7 +3012,6 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, > > i = 0; > > nfrags = skb_shinfo(list_skb)->nr_frags; > > frag = skb_shinfo(list_skb)->frags; > > - frag_skb = list_skb; > > > > BUG_ON(!nfrags); > > > > @@ -3016,8 +3026,6 @@ struct sk_buff *skb_segment(struct sk_buff *head_skb, > > goto err; > > } > > > > - if (unlikely(skb_orphan_frags(frag_skb, GFP_ATOMIC))) > > - goto err; > > > > *nskb_frag = *frag; > > __skb_frag_ref(nskb_frag); > > -- > > 1.7.9.5 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
