On Tue, Feb 11, 2014 at 07:24:04AM -0800, Eric Dumazet wrote: > On Tue, 2014-02-11 at 22:25 +0800, Qin Chuanyu wrote: > > we could xmit directly instead of going through softirq to gain > > throughput and lantency improved. > > test model: VM-Host-Host just do transmit. with vhost thread and nic > > interrupt bind cpu1. netperf do throuhput test and qperf do lantency test. > > Host OS: suse11sp3, Guest OS: suse11sp3 > > > > latency result(us): > > packet_len 64 256 512 1460 > > old(UDP) 44 47 48 66 > > new(UDP) 38 41 42 66 > > > > old(TCP) 52 55 70 117 > > new(TCP) 45 48 61 114 > > > > throughput result(Gbit/s): > > packet_len 64 512 1024 1460 > > old(UDP) 0.42 2.02 3.75 4.68 > > new(UDP) 0.45 2.14 3.77 5.06 > > > > TCP due to the latency, client couldn't send packet big enough > > to get benefit from TSO of nic, so the result show it will send > > more packet per sencond but get lower throughput. > > > > Eric mentioned that it would has problem with cgroup, but the patch > > had been sent by Herbert Xu. > > patch_id f845172531fb7410c7fb7780b1a6e51ee6df7d52 > > > > Signed-off-by: Chuanyu Qin <qinchuanyu@xxxxxxxxxx> > > --- > > drivers/net/tun.c | 4 +++- > > 1 files changed, 3 insertions(+), 1 deletions(-) > > > > diff --git a/drivers/net/tun.c b/drivers/net/tun.c > > index 44c4db8..90b4e58 100644 > > --- a/drivers/net/tun.c > > +++ b/drivers/net/tun.c > > @@ -1184,7 +1184,9 @@ static ssize_t tun_get_user(struct tun_struct > > *tun, struct tun_file *tfile, > > skb_probe_transport_header(skb, 0); > > > > rxhash = skb_get_hash(skb); > > - netif_rx_ni(skb); > > + rcu_read_lock_bh(); > > + netif_receive_skb(skb); > > + rcu_read_unlock_bh(); > > > > tun->dev->stats.rx_packets++; > > tun->dev->stats.rx_bytes += len; > > I already said this patch is not good : > > rcu_read_lock_bh() makes no sense here. > > What is really needed is local_bh_disable(); > > Herbert patch ( http://patchwork.ozlabs.org/patch/52963/ ) had a much > cleaner form. > > Just use it, CC him, credit him, please ? > But not before making sure (testing) that patch does not break the cgroups classifier please. -- MST -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
