Re: priority

[Devendra Singh Mahra <devendra.sm@xxxxxxxxx>]

hi, as far as i know, it is the I/O bound processes which are given higher priority and higher time slice.

 this is to ensure better response time .  it seems that u r confused because u might have read that higher priority 
processes get longer time slice and the other statement that I/O bound processes dont need a longer timeslice 
seem to be contradictory.

  actually giving a longer time slice to I/o bound process doesn't mean that the process will consume whole time slice in
a single burst . the consumption of the time slice may be distributed
over a number of bursts . the I/o bound processes consume their time
slice spread over a number of bursts. the allocation of a longer time
slice to an i/o bound process doesnt affect responsiveness as the
process will itself leave the cpu and wait for some i/o even before the
expiry of the time slice.

   on the other hand the processor bound processes do need a
longer time slice but if a longer time slice is given to a cpu bound
process , it will hog up the cpu for a long time and thus hampering the
system response.

 you can read the scheduling chapter of linux kernel development
by robert love ( to get the idea clearly ) feel free for getting
further explanation ( i may not have been able to explain it clearly )

On 9/3/05, raja <vnagaraju@xxxxxxxxxxxx > wrote:

Hi,
    I am a bit confused of relation between priority and time slice.
In a book i have studied It is given that higher priority processes will
get longer time slice.
And I/O bounded process will get elevated priority.

and some where in the same book it is written that I/O Bounded processes
do not need larger time slices.
Will you please clear the doubt.Which needs the highest piority and time
slice


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