Re: realloc() - frequency, conditions, or experiences about relocation?

On 19/06/2024 07:48, David Duffy wrote:

In sci.stat.math Anton Shepelev <anton.txt@g{oogle}mail.com> wrote:

[cross-posted to: ci.stat.math]
>
Malcolm McLean:
>

We have a continuously growing buffer, and we want the
best strategy for reallocations as the stream of
characters comes at us. So, given we now how many
characters have arrived, can we predict how many will
arrive,

>
Do you mean in the next bunch, or in total (till the end of
the buffer's lifetime)?
>

Isn't this a halting problem?  Aren't the more important data:
how much memory the user is allowed to allocate, the properties of
the current system's memory allocation algorithm, when your stream
will have to go to disc or other slow large volume storage, how
the stream can be compressed on the fly (the latter might well give
strong predictions for future storage requirements based on what
has been read to date).
 

No. We have to have some knowledge. And what we probaby know is that the input is a file stored on someone's personal computer. And someone has published on the statistical distribution of such files And they have a log-normal distribution with a mean and a median which he gives. So with that informaton, we can work out, given that a file is at least N characters, what is the prbablity that an allocation of any size will contain the whole file, and how many bytes, on average will be wasted.
Statistical analysis can't tell us what a allocation wil cost versus the cost of hoggng memory we don't need, however. It can;t tell us what to do. Just put us in the picture.
--
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http://malcolmmclean.github.io/babyxrc