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Date: Wed, 27 Aug 2008 09:17:06 -0700 From: Stephen Hemminger <shemminger@...tta.com> To: Andi Kleen <andi@...stfloor.org> Cc: Evgeniy Polyakov <johnpol@....mipt.ru>, Eric Dumazet <dada1@...mosbay.com>, Denys Fedoryshchenko <denys@...p.net.lb>, netdev@...r.kernel.org, linux-kernel@...r.kernel.org Subject: Re: loaded router, excessive getnstimeofday in oprofile On Wed, 27 Aug 2008 14:54:12 +0200 Andi Kleen <andi@...stfloor.org> wrote: > Evgeniy Polyakov <johnpol@....mipt.ru> writes: > > > > Yup, this innocent toys can end up with this such behaviour on modern > > highly loaded machines. > > I and also other people had some patches to move the time stamp > measuring into the socket. This way the time stamping didn't need to > be enabled on all packets, only on those that actually end up at a > socket that requires the time stamp. > > Unfortunately DaveM didn't like it because some bank wanted > different semantics, see the discussion in > http://thread.gmane.org/gmane.linux.network/91679 > > Perhaps you can find out which bank it was and send them a bill for > your CPU time ;-) > > -Andi > Look at /proc/net/ptype to see if any AF_PACKET sockets are open. There are several causes of this: * Applications like DHCP use AF_PACKET when they could use something else * AF_PACKET API was poorly designed and always has timestamps * The choice was made to get more accurate timestamps by stamping early in receive code. A better alternative would be to do it in protocol handler after the socket filter. Sorry, Andi socket layer is too late. * No driver is using hardware mechanisms to get accurate/free timestamps. I was working on sky2, but never was stable/complete. Easist advice now is to fix userspace. -- To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
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