On Sat, Oct 30, 2010 at 11:32:12AM +0900, Simon Horman wrote: > On Fri, Oct 29, 2010 at 02:57:57PM -0400, Howard M. Kash (Civ, ARL/CISD) > wrote: > > > > After upgrading from 2.6.35.4 (with OPS patch) to 2.6.36, ksoftirqd > > process (eight of them) went from using 5-15% CPU each to using 15-40% > > CPU each. Load average went from around 0.6 to around 2. The server is > > round-robin load balancing about 19,000 UDP and 90 TCP DNS connection per > > second. UDP uses OPS. Broadcom NIC cards are using MSI. With MSI > > disabled, load average is 0.11 and only one or two ksoftirqd process use > > <5% CPU. > > > > Could the nf_conntrack changes have caused this? There were also many > > MSI and bnx2 updates in 2.6.36, so not sure if it's LVS or not. > > Hi Howard, > > Yes, it is very likely that the problem you are seeing > is a regression caused by the introduction of full-NAT. > > There is a fix for this, which will be included in 2.6.37-rc1 > but unfortunately it was to invasive to include in 2.6.36 as > the problem was noticed fairly late in the release cycle. > > As I understand it, the fix that was made by the three patches > listed below. > > These patches appear to apply cleanly on top of 2.6.36. > The v2.6.36-nfct branch of > git://git.kernel.org/pub/scm/linux/kernel/git/horms/lvs-test-2.6.git > is 2.6.36 plus these three patches. > > I believe that even with these patches in order to avoid the performance > penalty you need to set /proc/sys/net/ipv4/vs/snat_reroute to 0. > > > > commit 8a8030407f55a6aaedb51167c1a2383311fcd707 > Author: Julian Anastasov <[email protected]> > Date: Tue Sep 21 17:38:57 2010 +0200 > > ipvs: make rerouting optional with snat_reroute > > Add new sysctl flag "snat_reroute". Recent kernels use > ip_route_me_harder() to route LVS-NAT responses properly by > VIP when there are multiple paths to client. But setups > that do not have alternative default routes can skip this > routing lookup by using snat_reroute=0. > > Signed-off-by: Julian Anastasov <[email protected]> > Signed-off-by: Patrick McHardy <[email protected]>
Julian, do you think that it would be possible to add some auto-detection that turns snat_reroute on and off as necessary? _______________________________________________ Please read the documentation before posting - it's available at: http://www.linuxvirtualserver.org/ LinuxVirtualServer.org mailing list - [email protected] Send requests to [email protected] or go to http://lists.graemef.net/mailman/listinfo/lvs-users
