Re: buildfarm animals and 'snapshot too old'

On 05/15/2014 03:57 PM, Tomas Vondra wrote:
>> How long does a CLOBBER_CACHE_RECURSIVELY run take? days or weeks seems
>> kinda nuts.
> I don't know. According to this comment from cache/inval.c, it's expected
> to be way slower (~100x) compared to CLOBBER_CACHE_ALWAYS.
>
> /*
>   * Test code to force cache flushes anytime a flush could happen.
>   *
>   * If used with CLOBBER_FREED_MEMORY, CLOBBER_CACHE_ALWAYS provides a
>   * fairly thorough test that the system contains no cache-flush hazards.
>   * However, it also makes the system unbelievably slow --- the regression
>   * tests take about 100 times longer than normal.
>   *
>   * If you're a glutton for punishment, try CLOBBER_CACHE_RECURSIVELY. This
>   * slows things by at least a factor of 10000, so I wouldn't suggest
>   * trying to run the entire regression tests that way.It's useful to try
>   * a few simple tests, to make sure that cache reload isn't subject to
>   * internal cache-flush hazards, but after you've done a few thousand
>   * recursive reloads it's unlikely you'll learn more.
>   */
>

Yes, I've seen that. Frankly, a test that takes something like 500 hours 
is a bit crazy.

If we really want to run this in the buildfarm we should probably try to 
create a massively cut down test schedule for use in this case.

Incidentally, should the CLOBBER_CACHE_ALWAYS machines also be defining 
CLOBBER_FREED_MEMORY?

cheers

andrew