On Wed, 28 Dec 2005 22:35:50 -0500 Bill Fink <[EMAIL PROTECTED]> wrote:
> On Thu, 15 Dec 2005, Stephen Hemminger wrote: > > > On Fri, 16 Dec 2005 03:26:31 +0100 > > Andi Kleen <[EMAIL PROTECTED]> wrote: > > > > > On Thu, Dec 15, 2005 at 08:35:32PM -0500, Bill Fink wrote: > > > > On Fri, 16 Dec 2005, Andi Kleen wrote: > > > > > > > > > > It appears that it is getting CPU starved for some reason (note the > > > > > > 43%/40% transmitter CPU usage versus the 99%/99% CPU usage for the > > > > > > 2.6.12.6 case). > > > > > > > > > > What happens when you turn off tso in ethtool? > > > > > > > > Thanks!!! That did the trick. > > > > > > TSO is still a bit of work in progress. The old 2.6.12 TSO code > > > actually ignored the congestion window and was illegal in benchmarks etc > > > (and might have even been dangerous to the internet). That was fixed, > > > but performance still didn't fully recover. It's a tricky problem. > > > > And it wasn't till 2.6.15 that we got the fix in to correctly > > increase cwnd with TSO. > > Update: > > I just now tested with 2.6.15-rc7 and it seems to work fine with > TSO enabled. > > chance% cat /proc/version > Linux version 2.6.15-rc7-bf-smp ([EMAIL PROTECTED]) (gcc version 3.2 20020903 > (Red Hat Linux 8.0 3.2-7)) #1 SMP Wed Dec 28 19:35:55 EST 2005 > > [EMAIL PROTECTED] ethtool -k eth0 > Offload parameters for eth0: > rx-checksumming: on > tx-checksumming: on > scatter-gather: on > tcp segmentation offload: on > > chance% nuttcp -w2m 192.168.88.8 > 6054.1250 MB / 10.01 sec = 5073.1546 Mbps 100 %TX 72 %RX > chance% nuttcp -r -w2m 192.168.88.8 > 6090.4375 MB / 10.01 sec = 5103.6174 Mbps 100 %TX 70 %RX > > That's expected TCP performance levels of slightly over 5 Gbps, > although I thought I might get some CPU back with TSO enabled > (note the transmitter is still pegged at 100%). > > Would the following patch be at all useful for the 2.6.14.x stable > series, since enabling TSO there causes a 40% or greater TCP performance > penalty, or is 2.6.15 final so imminenent that it wouldn't be > considered useful? > > Signed-off-by: Bill Fink <[EMAIL PROTECTED]> > > --- linux-2.6.14.3.orig/drivers/net/ixgb/ixgb_main.c 2005-11-24 > 17:10:21.000000000 -0500 > +++ linux-2.6.14.3/drivers/net/ixgb/ixgb_main.c 2005-12-28 > 01:06:05.000000000 -0500 > @@ -445,7 +445,8 @@ > NETIF_F_HW_VLAN_RX | > NETIF_F_HW_VLAN_FILTER; > #ifdef NETIF_F_TSO > - netdev->features |= NETIF_F_TSO; > + /* TSO not performant at present - disable by default */ > + netdev->features &= ~NETIF_F_TSO; > #endif > > if(pci_using_dac) doesn't make sense to patch just one driver. It would make more sense to backport the TSO cwnd patch from 2.6.15 -- Stephen Hemminger <[EMAIL PROTECTED]> OSDL http://developer.osdl.org/~shemminger - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
