[AceJohnny2]

> In other words: your system supports calling the time system call via the Linux kernel’s vDSO to avoid the cost of switching to the kernel. But, as soon as your program calls time, it calls localtime immediately after, which invokes a system call anyway.

This reminds me of an article by Ted Unangst[1], in which he flattens the various libraries and abstractions to show how xterm (to cite one of many culprits) in one place is effectively doing:

        if (poll() || poll())
        while (poll()) {
             /* ... */
        }

In other words, if you don't know what your library/abstraction is doing, you can end up accidentally duplicating its work.

Reminds me of some aphorism, "Those who do not learn from history..." ;)

[1] http://www.tedunangst.com/flak/post/accidentally-nonblocking

discussed https://news.ycombinator.com/item?id=11847529

[nsxwolf]

Those who quote George Santayana are condemned to repeat him.

[andrewbinstock]

Those who don't know George Santayana are condemned to repeat him. FTFY.

[koverstreet]

You seem to have missed the joke...

[btown]

You seem to have missed the joke... wait a second...

[andrewbinstock]

Totally got it. It's a refinement of the line. As the person below understands.

[barrystaes]

Apparently, i under stand.

[segmondy]

With the layering of clusters, containers, micro services, bet you probably have 10x worse than that. There is always a cost to abstraction. On the surface it might make things simpler but if you were to peel it apart, you would reveal a hidden layer of complexity. Hopefully, it's done well right enough that there will never be a need to peel it apart.

[nomel]

> On the surface it might make things simpler but if you were to peel it apart, you would reveal a hidden layer of complexity.

Well yes, This is the very definition and goal of abstraction.

[jwhitlark]

This is why I always liked the idea of Unikernels, they let us reset our abstractions without giving up all we've learned in the last couple decades.

[JdeBP]

Xe just did mplayer as well. It calls non-blocking select(), then non-blocking poll(), then nanosleep(), in a loop.

* http://www.tedunangst.com/flak/post/mplayer-ktracing