Re: [platform-testers] [Grep-devel] new snapshot available: grep-2.25.101-be82

[Jim Meyering]

On Mon, Sep 26, 2016 at 8:48 PM, Bruce Dubbs <address@hidden> wrote:
...
>> regexps. First it times the use of a shorter one, then it times the
>> use of a regexp whose byte count is 10 times larger than the first
>> one. The test requires that the latter duration be no longer than 20x
>> the duration of the first run. In your case, it actually took 80ms
>> longer than the 400ms that would be 20x.
>>
>> As mentioned in its comments, that test is sensitive to load and
>> timing. Can you reproduce that failure consistently when running that
>> test in isolation? I.e., run this a few times:
>>
>>    check -C tests TESTS=long-pattern-perf RUN_EXPENSIVE_TESTS=yes
>>
>> I may end up changing it to run the quick one 5 times, and use the
>> minimum time to compare against the duration of the longer-running
>> command also being run 5 times (or until passing).
>
>
> Using the above, I ran it about 6 times and it only passed twice.  I do have
> several apps open but I have 'load average: 0.01, 0.06, 0.05'
>
> $ free
>               total    used    free      shared  buff/cache   available
> Mem:        8051948 1724040 5279176      414404     1048732     5834340
> Swap:       2097148  361760 1735388

Then maybe it's cache effects: much faster with all-in-cache smaller
search string.
Please see if this patch (quadrupling each regexp size) makes it pass
consistently:

grep-tests-long-pattern-perf-false-failure.diff
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