CPU cache? Cx states? powerd?
On Tue, Apr 10, 2012 at 03:40:27PM -0700, Julian Elischer wrote: > On 4/10/12 3:52 PM, Luigi Rizzo wrote: > > I noticed this first on a 10G interface, but now there seems > > to be a similar issue on the loopback. > > > > Apparently a ping -f has a much lower RTT than one with non-zero > > delay between transmissions. Part of the story could be that > > the flood version invokes a non-blocking select. > > On the other hand, pinging on the loopback should make > > the response available right away, so what could be the reason > > for the additional 3..10us in the ping response time ? > > > > The following are numbers on an i7-2600k at 3400 MHz + turboboost, > > running stable/9 amd64. Note how the min ping time significantly > > increases moving from flood to 10ms to 1s. > > On an Intel 10G interface i am seeing a min of 14-16us with > > a ping flood, and up to 33-35us with the standard 1s interval > > (using -q probably trims another 2..5us) > > I'd suggest some ktr points around the loopback path.. _______________________________________________ freebsd-current@freebsd.org mailing list http://lists.freebsd.org/mailman/listinfo/freebsd-current To unsubscribe, send any mail to "freebsd-current-unsubscr...@freebsd.org"
