On Mon, 2006-12-18 at 00:37 +0200, Matti Aarnio wrote: > On Sun, Dec 17, 2006 at 10:23:54AM -0800, Randy Dunlap wrote: > > J.H. wrote: > ... > > >The root cause boils down to with git, gitweb and the normal mirroring > > >on the frontend machines our basic working set no longer stays resident > > >in memory, which is forcing more and more to actively go to disk causing > > >a much higher I/O load. You have the added problem that one of the > > >frontend machines is getting hit harder than the other due to several > > >factors: various DNS servers not round robining, people explicitly > > >hitting [git|mirrors|www|etc]1 instead of 2 for whatever reason and > > >probably several other factors we aren't aware of. This has caused the > > >average load on that machine to hover around 150-200 and if for whatever > > >reason we have to take one of the machines down the load on the > > >remaining machine will skyrocket to 2000+. > > Relaying on DNS and clients doing round-robin load-balancing is doomed. > > You really, REALLY, need external L4 load-balancer switches. > (And installation help from somebody who really knows how to do this > kind of services on a cluster.)
While this is a really good idea when you have systems that are all in a single location, with a single uplink and what not - this isn't the case with kernel.org. Our machines are currently in three separate facilities in the US (spanning two different states), with us working on a fourth in Europe. > > >Since it's apparent not everyone is aware of what we are doing, I'll > > >mention briefly some of the bigger points. > ... > > >- We've cut back on the number of ftp and rsync users to the machines. > > >Basically we are cutting back where we can in an attempt to keep the > > >load from spiraling out of control, this helped a bit when we recently > > >had to take one of the machines down and instead of loads spiking into > > >the 2000+ range we peaked at about 500-600 I believe. > > How about having filesystems mounted with "noatime" ? > Or do you already do that ? We've been doing that for over a year. - John - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
