ITPEC FE Morning October 2022 Question 15
An information processing system consists of a database and web server with the specifications shown in the table below.
When the throughput of an entire processing system is determined by the throughput of the server with the lowest throughput, what is the throughput of the entire processing system in TPS (transactions per second)? Here, the throughput of a server is calculated by multiplying the number of transactions in a second with the upper limit of CPU utilization. A database and web server perform the processing independently, and there is one CPU in each server.
Explanation
160 TPS — compute each server's throughput, then take the lower one, the bottleneck.
The system runs at the rate of its slowest server: the smaller of 160 and 225 is 160 TPS.
Answer (a)
Why not others:
- •(b) 225 — the web server's throughput; it is the faster server, so it does not set the system rate
- •(c) 250 — the web server at 100% CPU, ignoring both the utilization limit and the slower database server
- •(d) 385 — 160 + 225, adding the servers as if each handled separate transactions, when every transaction needs both
Key rule: When every transaction passes through each server, the system's throughput is the minimum of the servers' throughputs, never their sum.
System Component · AI-written, may contain errors
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