It's worth making the point that this is only when dumping the stats.
Stats collection hasn't changed.  If performance of the dump is really
a concern, I'm sure I can offer some suggestions to improve things.

On Wed, Jan 23, 2013 at 9:22 AM, Andreas Hansson
<[email protected]> wrote:
> Hi Steve,
>
> I occurs when only using the SQL output, i.e. old text only replaced with
> new SQL only. Adding text output to the latter unfortunately slows things
> down even more due to the additional formatting/formula evaluation etc.
>
> In a typical use-case the text formatting could be done after the
> simulation is done, so it would hopefully not be a problem. Dumping with
> high frequency with SQL and text would cause issues with performance.
>
> It's not perfect at this point, but by having a broader audience we can
> hopefully fix these issues much faster.
>
> Andreas
>
> On 23/01/2013 16:15, "Steve Reinhardt" <[email protected]> wrote:
>
>>Hi Andreas,
>>
>>Sorry I have not had time to look at your patches, but I fully support
>>what
>>you're doing in principle.
>>
>>One clarification about the slowdown: does this occur even when you use
>>text output, or does it occur only when you use SQL?  That is, will users
>>who stick with text output be affected, or are you merely lamenting that
>>SQL is slower than text output when that shouldn't necessarily be the
>>case?
>> If it's the latter, I'm absolutely fine with it; if it's the former, then
>>I'm a bit more concerned.
>>
>>Thanks,
>>
>>Steve
>>
>>
>>On Wed, Jan 23, 2013 at 7:10 AM, Andreas Hansson
>><[email protected]>wrote:
>>
>>> Hi all,
>>>
>>> The short version:
>>>
>>> A week ago I posted a number of review requests that build on top of
>>> Nate's initial work to move the stats from C++ to Python. The reviews,
>>> request 1636 to 1647, has not gotten any comments so far, and I would
>>>like
>>> to know if people are generally happy with these patches being pushed.
>>>Are
>>> you happy to move to a Python-based stats system with SQL output even
>>> though it currently involves a performance hit?
>>>
>>> The longer version:
>>>
>>> The main benefit of the new stats system is the flexibility in the stats
>>> processing, with the SQL output being the first example of this. The old
>>> text output is still available as an option, but for any post processing
>>> the SQL output removes the need to create complex regular expressions
>>>and
>>> parse strings back into numbers/vectors/distributions etc.
>>>
>>> There is already an API available for querying the database, and our
>>>hope
>>> is that this will be expanded upon by the users going forward. There is
>>> also a possibility to add functionality that would allow dumping stats
>>>for
>>> only certain components etc.
>>>
>>> Lots of exciting new features and possibilities in other words, but
>>>also a
>>> slight hit in performance. Although it has already been optimised
>>>compared
>>> to the initial implementation, it is still more costly than the old text
>>> output. For a detailed simulation, with dumps every 100k instructions,
>>>the
>>> simulation time goes from 11 s to 19 s. Our hope is to get this pushed
>>>out
>>> to get a  broader audience helping to improve both the speed and the
>>> functionality.
>>>
>>> Thanks,
>>>
>>> Andreas
>>>
>>>
>>>
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