Difference between Uniform Memory Access (UMA) and Non-uniform Memory Access (NUMA)
Multiprocessors can be categorized into three shared-memory model which are:
- Uniform Memory Access (UMA)
- Non-uniform Memory Access (NUMA)
- Cache-only Memory Access (COMA)
Uniform Memory Access (UMA):
In UMA, where Single memory controller is used. Uniform Memory Access is slower than non-uniform Memory Access. In Uniform Memory Access, bandwidth is restricted or limited rather than non-uniform memory access. There are 3 types of buses used in uniform Memory Access which are: Single, Multiple and Crossbar. It is applicable for general purpose applications and time-sharing applications.

Non-uniform Memory Access (NUMA):
In NUMA, where different memory controller is used. Non-uniform Memory Access is faster than uniform Memory Access. Non-uniform Memory Access is applicable for real-time applications and time-critical applications.

Let’s see the difference between UMA and NUMA:
| S.NO | UMA | NUMA |
|---|---|---|
| 1. | UMA stands for Uniform Memory Access. | NUMA stands for Non-uniform Memory Access. |
| 2. | In Uniform Memory Access, Single memory controller is used. | In Non-uniform Memory Access, Different memory controller is used. |
| 3. | Uniform Memory Access is slower than non-uniform Memory Access. | Non-uniform Memory Access is faster than uniform Memory Access. |
| 4. | Uniform Memory Access has limited bandwidth. | Non-uniform Memory Access has more bandwidth than uniform Memory Access. |
| 5. | Uniform Memory Access is applicable for general purpose applications and time-sharing applications. | Non-uniform Memory Access is applicable for real-time applications and time-critical applications. |
| 6. | In uniform Memory Access, memory access time is balanced or equal. | In non-uniform Memory Access, memory access time is not equal. |
| 7. | There are 3 types of buses used in uniform Memory Access which are: Single, Multiple and Crossbar. | While in non-uniform Memory Access, There are 2 types of buses used which are: Tree and hierarchical. |
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