Number of CPUs supported

[Bruce Owen Lee]

I am trying to find a definitive source on the number of CPUs supported in Linux, especially on the Integrity platform. I have a need to go beyond 16 CPUs but am hearing conflicting info on whether or not it is supported. Also, is there not a demishing return after a certain number CPUs?

[David Claypool]

"Building on eight-way Linux support it introduced in August 2004, HP is the first major vendor to scale Linux to 64-way on a standard Linux kernel through a project code-named "Big Tux." This will help eliminate the risks associated with custom kernel implementations, such as those offered by competing firms.

With five years of expertise in scaling out data center platforms, HP is responding to customer demand by supporting higher levels of scalability for Linux by offering more viable options between low and high-end standards-based HP servers."

http://www.hp.com/hpinfo/newsroom/press/2005/050215a.html

[Ivan Krastev]

See "Maximum Processors/Cores per nPar" table at page 5 here - http://h18000.www1.hp.com/products/quickspecs/12650_div/12650_div.PDF


regards,
ivan

[rick jones]

Diminishing return after a certain number of CPUs is a _classic_ "It Depends" situation. The best way to go about it short of just trying it yourself would be to arrange some time in one of the Solutions Centers (aka Capacity Planning Centers) and try your workload there.

If you are going beyond 16 CPUs that suggests you have an HP Sales contact engaged or at least a reseller, either of whom should be able to assist you with getting time in one of the Solution Centers. It is often possible to arrange to have the access be remote if you do not wish to travel to the Solution Center nearest you.

[Matti_Kurkela]

Ivan's document gives good details:
for example, RedHat Enterprise Linux 4 supports up to 64 CPU cores with a default installation. Apparently the system works even if you have more CPU cores, but it just doesn't use the extra cores.

If you install a "largesmp" version of the RedHat kernel package, you can go to 128 cores (64 physical dual-core CPUs).