Cycle Stealing DMA Doubt

Question

Consider x = CPU time or data preparation time = 1 microsecond 

and y = data transfer time from DISK to DMA = 21 microseconds.

% of memory cycles stolen =  1/(21) * 100  = 4.76%

Doubt - For each 21 memory cycle, 1 memory cycle will be taken to transfer data. CPU can do its own work for 20 memory cycles and 1 memory cycle it will remain idle.

What does this CPU cycle stealing means ?

Comments

@iarnav  @Mk Utkarsh   @neeraj33negi   @HeadShot   @Ajit J  @prashant jha 1

I would request all of you to please check these links

1)https://gateoverflow.in/116524/coa-dma-doubt?show

2)https://gateoverflow.in/?qa=blob&qa_blobid=18388358629298189207

I was kind of under wrong impression about this topic so some things which I said was not right. Please accept my apology _/\_ :(

 

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@MiNiPanda 

Please kindly edit the points in your answer where you feel you were wrong coz rest is beautifully written.

Ping after done . Thanks for the correction. :)

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@HeadShot

I found these links today morning and realized I have to revise this part again..There is a lot of confusion and sums related to this concept are often difficult for me to solve..I can't edit my previous comment because I am not sure what I'll write now might be found wrong some other day :P

Instead I am adding a note there so that other users don't get misled in future..