On 9/14/05, Raghu Vadapalli <iprsvp@xxxxxxxxx> wrote: > On 9/14/05, Andre Luiz da Silva <andrack@xxxxxxxxx> wrote: > > Hello Friends! > > > > I'm studying the kernel memory management in the Linux Kernel, with the > > book: > > "Understanding the Linux Virtual Memory Manager", but I don't understading > > the > > "fundamental" direferences between NUMA and UMA memory architeture. > > > > I perform a serach at the Google and the Kernel Documentation > > (Documentation/vm/numa), > > but this make me very confused... > > > > Do Somebody has any explanation about the concepts of NUMA and UMA memory > > architeture? > > > > > > Thanks!!! > > > JUST FIXING MY TOP POSTING...BEFORE SOMEONE POINTS IT OUT. > AFAIU, > > UMA --- CPU to Memory bank access times are same. > > NUMA -- CPU to memory bank access times are different for different cpus. > > So you always want to allocate from the memory bank which is near to you. > > correct me if I am wrong. > Raghu > UMA has Uniform Memeory Access time, means memory is shared between several processors and NUMA is Non-Uniform Memory Access in which processors are assigned their own memory banks which are closer to it and have less access time !!!! Here I m attaching a gif to make it clear ........... Definations from google search for NUMA: NUMA (non-uniform memory access) is a method of configuring a cluster of microprocessor in a multiprocessing system so that they can share memory locally, improving performance and the ability of the system to be expanded. NUMA is used in a symmetric multiprocessing (SMP) system. An SMP system is a "tightly-coupled," "share everything" system in which multiple processors working under a single operating system access each other's memory over a common bus or "interconnect" path. Ordinarily, a limitation of SMP is that as microprocessors are added, the shared bus or data path get overloaded and becomes a performance bottleneck Non-Uniform Memory Architecture. Usually on an SMP system, all memory beyond the caches costs an equal amount to reach for each CPU. In NUMA systems, some memory can be accessed more quickly than other parts. Later kernels have some NUMA support for preferring to use memory "nearer" to the CPU, rather than higher-latency distant memory -- Fawad Lateef -- Kernelnewbies: Help each other learn about the Linux kernel. Archive: http://mail.nl.linux.org/kernelnewbies/ FAQ: http://kernelnewbies.org/faq/
