Re: [Valgrind-developers] AMD64 rounding support

[John R. <jr...@bi...>]

On 05/03/2013 07:26 AM, Sebastian Feld wrote:
> On Fri, May 3, 2013 at 10:52 AM, Julian Seward <js...@ac...> wrote:
>>
>>> keeps getting stalled.  I don't want to sound overly pushy, but it would
>>> help me a bit to at least know generally what is holding it up.  General
>>> disinterest?  Disappointment with a 4% slowdown in some cases?
>>
>> I think the fact that this is somewhat of a niche item, plus the potential
>> slowdown.
> 
> Which slowdown? Are you serious? Shouldn't valgrind first try to get
> things running *correct* before trying to optimize performance? 

Late answers are also incorrect answers, even for a correctness checker.
memcheck is almost too slow already.  There are more than a few cases
in which memcheck is not used because memcheck takes too long.

A 4% slowdown means that a memcheck run that used to take an entire day
(for a program that takes an hour at normal speed) would take a whole hour
longer.  That can be too slow.  The probabilistic risk of an unrevealed error
can be less than the guaranteed cost of memcheck.  This happens often enough
that it causes serious consideration of the trade-offs.

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