| English | 의미 |
|---|---|
| sequential computing/siːˈkwenʃl kəmˈpjuːtɪŋ/ | 순차 계산 |
| Parallel computing/ˈpærəlel kəmˈpjuːtɪŋ/ | 병렬 계산 |
| processors/ˈprəʊsesəz/ | 프로세서 |
| Distributed computing/ˈdɪstrɪbjuːtɪd kəmˈpjuːtɪŋ/ | 분산 계산 |
| speedup/ˈspiːdʌp/ | 가속비 |
One step at a time
- Traditionally a computer runs steps one at a time.
- This is sequential computing 顺序计算: each step must finish before the next begins.
- It is simple, but it can be slow for big jobs.
- To go faster, we can do several steps at once.
In sequential computing:
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
One step at a time, in order.
Parallel and distributed
- Parallel computing 并行计算 uses several processors 处理器 in one machine to run parts of a task at the same time.
- Distributed computing 分布式计算 spreads a task across many separate computers, often in different places, connected by a network.
- Parallel = many processors, one machine. Distributed = many machines.
- Both aim to finish a large task faster.
Sequential, parallel, or distributed?
Sequential runs one step at a time; parallel uses several processors in one machine at once; distributed spreads a task across many separate computers.
Match each term to its meaning.
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
Parallel is one machine; distributed is many machines.
Speedup and its limit
- The benefit of parallel computing is measured by speedup 加速比:
- $\text{speedup} = \dfrac{\text{time using one processor}}{\text{time using several processors}}$.
- But any part that must run sequentially cannot be sped up by adding processors.
- So the sequential portion sets a floor — a hard cap on the total speedup.
A task takes 100 s on one processor and 40 s on several. What is the speedup?
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
speedup = 100 / 40 = 2.5×.
If 20 s of a 100 s task must run sequentially, what is the maximum possible speedup?
난이도 2/5 · 140 코인 + 오늘 첫 완료 시 소액 보너스
Even with infinite processors, 20 s remains: 100 / 20 = 5×.
Why can adding more processors never remove the speedup cap?
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
The sequential portion sets a floor on the total time.
Distributed computing suits huge jobs too big for one machine, like indexing the whole web.
난이도 1/5 · 100 코인 + 오늘 첫 완료 시 소액 보너스
The work splits naturally across thousands of computers.
When distributed shines
- Distributed solutions shine on huge jobs — enormous data sets, or a search engine indexing the whole web.
- The work is too big for one machine and splits naturally across thousands.
Speedup with a cap. A 100-second task has 80 s parallel and 20 s sequential. On 4 processors the parallel part is $80 / 4 = 20$ s, plus 20 s sequential = 40 s. Speedup $= 100 / 40 = 2.5\times$. Even with a million processors, the 20 s sequential remains, so speedup can never beat $100 / 20 = 5$.
Sequential computing runs one step at a time. Parallel computing uses several processors in one machine at once; distributed computing spreads work across many machines. Parallel gain is measured as speedup (one-processor time ÷ many-processor time), but the sequential part caps it (here, 5×).