Re: probably cause (and fix) for floating-point assist faults on itanium

From: Claudio Freire <klaussfreire(at)gmail(dot)com>
To: Greg Matthews <gregory(dot)a(dot)matthews(at)nasa(dot)gov>
Cc: pgsql-performance(at)postgresql(dot)org
Subject: Re: probably cause (and fix) for floating-point assist faults on itanium
Date: 2011-11-18 14:21:52
Message-ID: CAGTBQpYjs8GHBk1mf__dYVH=4g7ZK2jHrN7ubNYJtYX+47OzNg@mail.gmail.com
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On Thu, Nov 17, 2011 at 10:07 PM, Greg Matthews
<gregory(dot)a(dot)matthews(at)nasa(dot)gov> wrote:
>        if (smoothed_alloc <= (float) recent_alloc)
>                smoothed_alloc = recent_alloc;
>        else if (smoothed_alloc >= 0.00001)
>                smoothed_alloc += ((float) recent_alloc - smoothed_alloc) /
>                        smoothing_samples;
>

I don't think that logic is sound.

Rather,

if (smoothed_alloc <= (float) recent_alloc) {
smoothed_alloc = recent_alloc;
} else {
if (smoothed_alloc < 0.000001)
smoothed_alloc = 0;
smoothed_alloc += ((float) recent_alloc - smoothed_alloc) /
smoothing_samples;
}

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