$//$Example $7\mathrm{.}3$

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#include #include

$$

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struct char$\_$print

$\{$

char character; int count;

$\}$;

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void $*$print $($void $*$parameters$)$

$\{$

struct char$\_$print $*$p;

p $=($struct char$\_$print $*)$ parameters; int i;

for $($i$=0$; i$<$ p$->$count ; $++$i$)$ fputc$($p$->$character, stderr$)$;

pthread$\_$exit$($NULL$)$;

$\}$

int main$()$

$\{$

pthread$\_$t t$1\_$id; pthread$\_$t t$2\_$id;

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struct char$\_$print t$1\_$args; struct char$\_$print t$2\_$args;

$$

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t$1\_$args.character$=\text{'}1\text{'}$; t$1\_$args.count $=60$;

pthread$\_$create$($&t$1\_$id$,$ NULL, print, $($void $*)$ &t$1\_$args$)$;

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t$2\_$args.character$=\text{'}0\text{'}$; t$2\_$args.count $=100$;

pthread$\_$create$($&t$2\_$id$,$ NULL, print, $($void $*)$ &t$2\_$args$)$;

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pthread$\_$join$($t$1\_$id$,$NULL$)$; pthread$\_$join$($t$2\_$id$,$NULL$)$;

$\}$

$1-(1$ marks$)$ Compile and run Example $7\mathrm{.}3$ above and provide a sample output of the program.

$2-(1$ marks$)$ Remove the two pthread$\_$join$()$ function calls from Example $7\mathrm{.}3,$ re$-$compile as follows:

$ gcc $-$o example$73$ example$73.$c $-$l pthread then, run the program as follows:

$ $./$example$73$

What is the output of the program.

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$3-(1$ marks$)$ In question $2,$ explain why are you getting such an output and how to fix it$.$

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$4-(7$ marks$)$ Write a program that reports the scheduling behaviour of threads on a multi$-$CPU system. Use the following function to report on the CPU on which a thread is scheduled:

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#include #define $\_$GNU$\_$SOURCE int sched$\_$getcpu$()$

Your program must create three threads. Each thread will start in a separate function than the other threads. The general structure of the thread$-$startup function is that it will be in an infinite loop executing two statements:

$1-$ Report the thread number $($first$,$ second, third$),$ along with the CPU it was scheduled on

$2-$ Sleeps for $2$ seconds $($sleep$(2))$

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Note: To get an output that includes scheduling threads on multiple CPUs, the virtual machine running Ubuntu Linux has to be reconfigured.

If you're using VMWare Player, You can increase the number of CPUs available to the virtual machine by going to: Edit Virtual Machine Settings $->$ Hardware Tab $->$ Processors

and select the number of CPUs from the drop$-$box.

If you're using Virtual Box, go to: Machine $->$ Settings $->$ System $->$ Processor, and increase the number of processors in the text box.