Prev: FAQ 7.8 How do I declare/create a structure?
Next: check for file in $PATH
From: Oliver 'ojo' Bedford on 15 Mar 2010 05:22
Hi!

For testing purposes I would like to fill chunks of memory (say 20M) with
arbitrary data (say bytes with values 1,2,...255,1,...).

What would be the fastest method?

Oliver

From: J�rgen Exner on 15 Mar 2010 10:14
Oliver 'ojo' Bedford <newsojo(a)web.de> wrote:
>For testing purposes I would like to fill chunks of memory (say 20M) with
>arbitrary data (say bytes with values 1,2,...255,1,...).
>
>What would be the fastest method?

The easiest method would probably be to define a string with say 256
bytes and then use the x operator to repeat it.
I would guess it would also be quite fast because it uses perl interna
only and doesn't involve a user-level loop.

jue
From: bugbear on 15 Mar 2010 12:00
J�rgen Exner wrote:
> Oliver 'ojo' Bedford <newsojo(a)web.de> wrote:
>> For testing purposes I would like to fill chunks of memory (say 20M) with
>> arbitrary data (say bytes with values 1,2,...255,1,...).
>>
>> What would be the fastest method?
>
> The easiest method would probably be to define a string with say 256
> bytes and then use the x operator to repeat it.
> I would guess it would also be quite fast because it uses perl interna
> only and doesn't involve a user-level loop.

If speed is really important (it often isn't) you may be able
to repeatedly "double up" by copying the head of the 20Meg space to itself.

BugBear
From: Xho Jingleheimerschmidt on 15 Mar 2010 22:10
Oliver 'ojo' Bedford wrote:
> Hi!
>
> For testing purposes I would like to fill chunks of memory (say 20M) with
> arbitrary data (say bytes with values 1,2,...255,1,...).
>
> What would be the fastest method?
>
> Oliver

Why do you need the fastest way to do it? What would happen if you used
a method that was merely fast enough?

You should probably fill the memory in a way that is similar to the way
it would be filled in the situation you are constructing the test to
test. For example, by repeated linear .=, or by repeated exponential
..=, or by x operator.


Xho
From: Oliver 'ojo' Bedford on 17 Mar 2010 06:00
Am Mon, 15 Mar 2010 16:00:42 +0000 schrieb bugbear:

> Jürgen Exner wrote:
>> Oliver 'ojo' Bedford <newsojo(a)web.de> wrote:
>>> For testing purposes I would like to fill chunks of memory (say 20M)
>>> with arbitrary data (say bytes with values 1,2,...255,1,...).
>>>
>>> What would be the fastest method?
>>
>> The easiest method would probably be to define a string with say 256
>> bytes and then use the x operator to repeat it. I would guess it would
>> also be quite fast because it uses perl interna only and doesn't
>> involve a user-level loop.
>
> If speed is really important (it often isn't) you may be able to
> repeatedly "double up" by copying the head of the 20Meg space to itself.

Thanks for the help. I'll try both methods.

Speed is not important in my case - it's just a matter of convenience
(and impatience on my side).

Oliver

 |  Next  |  Last
Pages: 1 2
Prev: FAQ 7.8 How do I declare/create a structure?
Next: check for file in $PATH