4 ms·

Did you read the posted article? It spends a lot of time trying to figure out how to measure context switches. Which I carefully wrote up around 1995 and stil

Did you read the posted article? It spends a lot of time trying to figure out how to measure context switches. Which I carefully wrote up around 1995 and still works to this day. That's independent of the hardware and was sort of my point. This is a solved problem. And if you look at Table 10, the time for a context switch is remarkably similar to what it was 20 years ago (which means the OS is fatter, not surprising, it's scales up on SMPs now).

marcosdumay 10y ago
I got the impression you were talking about the numbers. In that I agree. You've got basically the same procedure written there for anybody to learn. And a nice tool that runs it.
- luckydude 10y ago
  The numbers are just a snapshot into history but what I measured and how it was measured is far more interesting. For example your comment "you've got basically the same procedure" isn'tquite right. If you read the paper, much effort was spent explaining to people that the baseline context switch is just a floor, what you will see in real life will be bigger since in real life a context switch is more that just a register file save/restore. Very few benchmark writers get that point but that's sort of the main point. Not getting it means you are doomed to be mislead.
  - luckydude 10y ago
    Replying to my own reply, I reread what they were doing and yeah, you are right, they do have basically the same procedure. My bad. Good on them for getting it (though I'll grumble that this was a solved problem, you can apt-get install it). But you were right, looks the same. Sorry about that.
    - marcosdumay 10y ago
      No problems. Overall, I'm glad you shared your paper, lmbench seems very nice.
      - luckydude 10y ago
        Cool, glad you aren't pissed. And this whole thread has made me want to do a lmbench follow on paper, just get a new set of results for 2017 for *BSD, Linux, MacOS and maybe Solaris (does anyone care about anything other than Linux, MacOS, Windows these days?).

marcosdumay 10y ago

I got the impression you were talking about the numbers. In that I agree. You've got basically the same procedure written there for anybody to learn. And a nice tool that runs it.

luckydude 10y ago
The numbers are just a snapshot into history but what I measured and how it was measured is far more interesting. For example your comment "you've got basically the same procedure" isn'tquite right. If you read the paper, much effort was spent explaining to people that the baseline context switch is just a floor, what you will see in real life will be bigger since in real life a context switch is more that just a register file save/restore. Very few benchmark writers get that point but that's sort of the main point. Not getting it means you are doomed to be mislead.
- luckydude 10y ago
  Replying to my own reply, I reread what they were doing and yeah, you are right, they do have basically the same procedure. My bad. Good on them for getting it (though I'll grumble that this was a solved problem, you can apt-get install it). But you were right, looks the same. Sorry about that.
  - marcosdumay 10y ago
    No problems. Overall, I'm glad you shared your paper, lmbench seems very nice.
    - luckydude 10y ago
      Cool, glad you aren't pissed. And this whole thread has made me want to do a lmbench follow on paper, just get a new set of results for 2017 for *BSD, Linux, MacOS and maybe Solaris (does anyone care about anything other than Linux, MacOS, Windows these days?).