Re: Dumping /dev/zero to the console

Andrew E. Mileski (aem@nic.ott.hookup.net)
Mon, 22 Jul 1996 12:17:10 -0400 (EDT)


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>>> On linux console, even as a non-priv user, do a:
>>> % dd if=/dev/zero bs=1024k
>>
>> For what it's worth, this has absolutely no effect on my machine when
>> using a block size of 1024 (not 1024k). I let it run for quite a while
>> (forgot it was running), and stopped it after about 90Gb.
>
> Of course. That is why I said 1024k and not 1024. There is a big
> difference. Or do you consider a factor of approx 1000 insignificant?

I tried it with bs=1024k on the slowest machine I have access to
(a P5-100 with 256k PB cache and 8Mb FPM RAM) running kernel v1.2.1.

The results were worse, but not a lock-up. The system CPU time went to
nearly 100%, but switching VCs was not affected. Response was slower
than normal, but the system was still usable. Memory consumption
did not increase (no swapping).

I see your point - any user can eat all the CPU time with this.
This is "Not a good thing". I don't know if the driver needs to be
adjusted, or perhaps we have to wait for CPU quotas.

- --
Andrew E. Mileski
mailto:aem@ott.hookup.net http://www.redhat.com/~aem/
Linux Plug-and-Play Project Leader http://www.redhat.com/linux-info/pnp/
PGP Public Keys: mail with 'Subject: help' to pgp-public-keys@keys.pgp.net

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