UGC NET CSE | December 2023 | Part 2 | Question: 51

Question

Which of the following statements is/are NOT CORRECT about NUMA ?

1. $\textrm{LOAD}$ and $\textrm{STORE}$ instructions are used to access remote memory.
2. There is a single address space visible to all CPU.
3. Access to local memory is slower than access to remote memory.
4. When the access time to remote memory is hidden, the system is called $\textrm{NC - NUMA}$.
5. In $\textrm{CC - NUMA}$, Coherent caches are present.

Choose the correct answer from the options given below :

• A. $\text{(I)}$ and $\text{(III)}$ Only
• B. $\text{(II)}$ and $\text{(IV)}$ Only
• C. $\text{(I)}$ and $\text{(V)}$ Only
• D. $\text{(III)}$ and $\text{(IV)}$ Only

Answer 1

OPTION - 4  

(A) LOAD and STORE instructions are used to access remote memory.

✅ CORRECT

Proof:
NUMA me single global address space hota hai.
Isliye chahe memory local ho ya remote, CPU usko normal LOAD/STORE instructions se hi access karta hai.
➡️ Ye DISTINCTIVE feature hai NUMA ka.

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(B) There is a single address space visible to all CPU.

✅ CORRECT

Proof:
NUMA = Non-Uniform Memory Access architecture
Par address space unified hota hai (distributed physical memory but logically shared)
➡️ Sab CPUs ek hi memory address space dekhte hain.

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(C) Access to local memory is slower than access to remote memory.

❌ INCORRECT

Proof:
NUMA ka core principle hi yeh hai:

Local Memory Access Time < Remote Memory Access Time\textbf{Local Memory Access Time < Remote Memory Access Time}Local Memory Access Time < Remote Memory Access Time

• Local memory = faster

• Remote memory = slower

Statement ne ulta likh diya, isliye (C) NOT CORRECT ✅

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(D) When the access time to remote memory is hidden, the system is called NC-NUMA.

❌ INCORRECT

Proof:
NC-NUMA ka full form hota hai:

Non-Cache Coherent NUMA\textbf{Non-Cache Coherent NUMA}Non-Cache Coherent NUMA

Iska latency hiding se koi lena-dena nahi hai.
NC-NUMA ka matlab hota hai:

• Caches coherent nahi hoti

Latency hiding = software/hardware optimization, NUMA type ka naam nahi.

Isliye (D) bhi NOT CORRECT ✅

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(E) In CC-NUMA, Coherent caches are present.

✅ CORRECT

Proof:
CC-NUMA = Cache Coherent NUMA
Iska matlab hi hota hai:

• Sab processors ki caches automatically coherent hoti hain