Re: [9fans] arm httpd

[Jeff Sickel <jas@corpus-callosum.com>]

> On Nov 9, 2014, at 2:21 PM, erik quanstrom <quanstro@quanstro.net> wrote:
> 
> On Sun Nov  9 14:51:37 EST 2014, jas@corpus-callosum.com wrote:
>> 
>>> On Nov 9, 2014, at 1:42 PM, erik quanstrom <quanstro@quanstro.net> wrote:
>>> 
>>> the aside leads me to believe that there is something wrong with the segment
>>> copy on fork.  since the semaphore in question is in the data segment,
>>> i'm going to guess that you're running the labs kernel, and you're hitting the
>>> page caching issue we've seen before.  does this happen on an atom kernel?
>> 
>> Only happens in the labs ARM kernel.  The labs mips and 386 kernels work fine
>> in this situation.
> 
> my thinking is that this isn't a defect in the arch-specific bits but rather a timing
> bug.  in that case, only manifesting on certain hardware is not diagnostic.
> 
> do you have any reason to believe this is not a timing bug?  it does fit the pattern
> rarely seen on x86 systems.  (actually (cf. the console appliance) there were ways
> to really make x86 systems suffer by forking fast enough on slow hardware.)

Well, sys/src/libc/9sys/time.c did change about the time I started seeing this bug
on my old dreamplug.

-jas