Re: kernel 2.6 speed

[Puneet Vyas]

Ciprian wrote:

> Hi guys!
>
> I got a question for you. Apparently kernel 2.6 is
> much slower then 2.4 and about 30 times slower then
> the windows one.
>
> I'm not an OS guru, but I ran a little and very simple
> test. The program bellow, as you can see, measures the
> number of cycles performed in 30 seconds.
>
> //----------------- START CODE --------------------
>
> #include <stdio.h>
> #include <time.h>
>
>
> int main()
> {
> time_t initialTime;
> time_t testTime;
> long counter = 0;
> double test = 1;
>
>
> time(&initialTime);
> testTime = initialTime;
>
> printf("Here we go...\n");
>
> while((testTime-initialTime) < 30)
> {
> time(&testTime);
> test /= 10;
> test *= 10;
> test += 10;
> test -= 10;
>
> counter ++;
>
> }
>
> printf("No. of cycles: %ld\n", counter);
>
> return 0;
> }
>
> //---------------- END CODE -------------------
>
>
> In windows were performed about 300 millions cycles,
> while in Linux about 10 millions. This test was run on
> Fedora 4 and Suse 9.2 as Linux machines, and Windows
> XP Pro with VS .Net 2003 on the MS side. My CPU is a
> P4 @3GHz HT 800MHz bus.
>
> I published my little test on several forums and I
> wasn't the only one who got these results. All the
> other users using 2.6 kernel obtained similar results
> regardless of the CPU they had (Intel or AMD). 
>
> Also I downloaded the latest kernel (2.6.12),
> configured it specifically for my machine, disabled
> all the modules I don't need and compiled it. The
> result was a 1.7 MB kernel on which KDE moves faster,
> but the processing speed it's the same - same huge
> speed ratios.
>
> Also, it shouldn't have any importance, but my HDD is
> SATA so the specific modules were required. I don't
> think its SCSI modules have any impact on the
> processing speed, but you know more on the kernel
> architecture then I do.
>
> Now, can anyone explain this and suggest what other
> optimizations I should use? The 2.4 version was a lot
> faster. I thought the newer versions were supposed to
> work faster (or at least just as fast) AND to offer
> extra features.
>
> Any help would appreciate.
>
> Thanks,
> Ciprian
>
>
>
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>  

Want to increase the latest kernel "speed" by 5 times ? Use the 
follwoing code instead. :)

// -- Start Code
#include <stdio.h>
#include <time.h>


int main()
{
clock_t initialTime;
clock_t testTime;
long counter = 0;
double test = 1;


initialTime = clock() / CLOCKS_PER_SEC;
testTime = initialTime;

printf("Here we go...\n");

while((testTime-initialTime) < 30)
{
testTime = clock()/CLOCKS_PER_SEC;
test /= 10;
test *= 10;
test += 10;
test -= 10;

counter ++;

}

printf("No. of cycles: %ld\n", counter);

return 0;
}
// ---- End code

so essentially you are timing just the time() function.

HTH,
Puneet
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