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SubjectRe: Linux version 2.1.113
On 3 Aug 1998, James H. Cloos Jr. wrote:

> Looking further in my archives, it was in 2.1.109 that WCHAN died.
>
> The change in fs/proc/array.c in 109 is irrelevant to wchan on i386.
> The changes to arch/i386/kernel/process.c and include/asm-i386/
> processor.h, however, seem more significant.
>
> -JimC
> --
> James H. Cloos, Jr.
> <cloos@jhcloos.com>
>

Yes. There are comments in the sources about adding a new wchan member
to the tss structure. This was done for the power-pc. At the time a
context-switch occurs, one could get the return address off the stack
and write it to the wchan member. The problem is that this would occur
at every context-switch which would add some overhead. The time to add
overhead, in my opinion, is the time at which one actually needs this
information.

Adding a new member would make this function much cleaner, but I
don't think others would appreciate the increased overhead. So,
I will wait and see. Presently, a simple hack results in the
address of the scheduler, which is not what we want.


Cheers,
Dick Johnson
***** FILE SYSTEM MODIFIED *****
Penguin : Linux version 2.1.113 on an i586 machine (66.15 BogoMips).
Warning : It's hard to remain at the trailing edge of technology.


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