On Thursday, 30 September 2010 at 6:50:29 -0700, Larry McVoy wrote:
> If you don't get the question you are not an
OS person,
> if you are, of course you get it.
Hmm. Am I expected to understand this? Seriously, I don't know how
many people really wrote anything like swtch ().
You'd be amazed at how many people did their own user level threads.
Gotta write swtch() for that.
I think you're missing the joke. But swtch () is a specific kernel
function in UNIX, though in this thread (excuse the pun) people seem
to be using it as a synonym for a scheduler. And not many people need
to write their threading library by hand any more.
And it's not swtch() so much as do you understand
the stack frames?
That's a different issue. Any programmer worth his salt needs to
understand the underlying hardware, including stack frames. For my
personal understanding of them, see
http://www.lemis.com/grog/Documentation/PUS/porting_unix_software/obj.pdf
towards the end, or
http://www.lemis.com/grog/Papers/Debug-tutorial/
for the kernel context, page 17 on.
If you could look at the stack frames and give me a
stack trace
that's more or less the same thing.
(gdb) bt
The real question is not to get a stack trace, but to analyse it.
Greg
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