[H-GEN] Clock Time Loss When Copying Files

Christopher Biggs chris at stallion.oz.au
Tue Jun 6 22:33:02 EDT 2000


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Martin Pool <mbp at linuxcare.com.au> moved upon the face of the 'Net and spake thusly:

> On Wed, 7 Jun 2000, Frank Brand wrote:
> 
> > 
> > It seems that wheh he does this the clock on the box being copied loses time.
> 
> I wonder if the machine is masking out timer interrupts while doing IO,
> and so losing time.  (Is it a slow machine or hard drive?)  

...or a dumb network card like an NE2000?[1]

If the network card is one that requires Programmed IO transfers, the
time spent at high interrupt priority will be considerable.

Using a NIC with shared memory or DMA support will improve matters
greatly.

In the interim, using NTP to synchronize clocks will improve matters
somewhat.

(The rest of Martin's suggestions are wise, as usual).

cjb

[1] For the uninitiated, the ubiquitous NE2000 (or clones) places a high
    load on the CPU in comparison to other network interface cards.

-- 
| Christopher J. Biggs -|- R & D Software Engineer --  Stallion Technologies |
| chris at stallion.oz.au -|- If it isn't broken, I just haven't touched it yet |
\---------veni vidi nuclei deceiri --- I came, I saw, I dumped core----------/

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