What Your Computer Does While You Wait : Gustavo Duarte
Popularity Report
 |
|||
|
|||
|
|||
|
|||
|
|||
|
Rank
URL Tag Cloud
Bookmark History
Saved by 18 people (-5 private), first by anonymouse user on 2008-12-01
- Philashman on 2009-08-24 - Tags Computer , hardware
- Navneetk on 2009-06-15 - Tags Performance , Computer-Architecture , Computing , Hardware , Windows
- Keyist on 2008-12-06 - Tags hardware , cpu
- Netvolution on 2008-12-06 - Tags Computer , Hardware
- Jisanali on 2008-12-05 - Tags tutorial , computers
Public Sticky notes
This post takes a look at the speed - latency and throughput - of various subsystems in a modern commodity PC, an Intel Core 2 Duo at 3.0GHz. I hope to give a feel for the relative speed of each component and a cheatsheet for back-of-the-envelope performance calculations. I’ve tried to show real-world throughputs (the sources are posted as a comment) rather than theoretical maximums. Time units are nanoseconds (ns, 10-9 seconds), milliseconds (ms, 10-3 seconds), and seconds (s). Throughput units are in megabytes and gigabytes per second. Let’s start with CPU and memory, the north of the northbridge:
Highlighted by bonsaibuddha
Highlighted by isaacmao
The first thing that jumps out is how absurdly fast our processors are. Most simple instructions on the Core 2 take one clock cycle to execute, hence a third of a nanosecond at 3.0Ghz. For reference, light only travels ~4 inches (10 cm) in the time taken by a clock cycle. It’s worth keeping this in mind when you’re thinking of optimization - instructions are comically cheap to execute nowadays.
Highlighted by isaacmao
one clock cycle to execute, hence a third of a nanosecond at 3.0Ghz. For reference, light only travels ~4 inches (10 cm) in the time taken by a clock cycle.
Highlighted by navneetk
To put this into perspective, reading from L1 cache is like grabbing a piece of paper from your desk (3 seconds), L2 cache is picking up a book from a nearby shelf (14 seconds), and main system memory is taking a 4-minute walk down the hall to buy a Twix bar
Highlighted by navneetk
For a discussion of all things memory, see Ulrich Drepper’s What Every Programmer Should Know About Memory (pdf), a fine paper on the subject.
Highlighted by navneetk
Keeping with the office analogy, waiting for a hard drive seek is like leaving the building to roam the earth for one year and three months.
Highlighted by navneetk
Filesystem defragmentation aims to keep files in continuous chunks on the disk to minimize seeks and boost throughput.
Highlighted by navneetk
Public Comment