Thanks a lot Andy, one this that is bothering me is,
Say if the load of procedures by executing the command mentioned by you is as
follows in descending order....
2604 __geneic_copy_to_user 40.6875
1705 csum_patrial_copy_generic 6.8750
370 __generic_copy_from_user 3.75
764 do_annonymous_page 3.1754
176 handle_IRQ_event 1.5714
31 remove_wait_queue 0.96
the list goes on
are these procedures condidered as load on the CPU? how much of a load ?
very high, high, moderate .....
If you can throw some light on this, it will be great.
Thanking You
Shesha
On Mon, 14 Apr 2003, Andy Pfiffer wrote:
> On Mon, 2003-04-14 at 15:17, Shesha@asu.edu wrote:
> > Hello Linux ppl,
> >
> > I have copuple of questions, I request you to share the information if you
> > know ....
>
> I have a partial answer.
>
> > --
> > 1
> > --
> > In the readprofile man page load=(# of clk ticks) / (length of the procedure)
> >
> > What does "length of procedure" means.
>
> My understanding after a quick read of the source is that "length of the
> procedure" means the length, in bytes, of the function. For most
> architectures, there is not a correlation between lines of code in
> assembler and number of executable bytes.
>
> On ARM all instructions are 4 bytes long (not counting "Thumb" style
> instruction encoding), but that does not mean 1 line of assembler source
> code is equal to 4 bytes worth of instructions.
>
> As far as I can tell, the "length of the procedure" is determined by the
> difference between sucessive symbols found in System.map:
>
> .
> .
> .
> c0109414 T sys_fork
> c010943c T sys_clone
> c0109474 T sys_vfork
> c01094a0 T sys_execve
> .
> .
> .
>
> sys_clone(), on my system, is 56 bytes long, including any alignment
> padding (0xc0109474-0xc010943c = 56).
>
>
>
> > Does that mean the # of ASM lines of
> > the procedure code? What is the units of the load. It cannot be %. because
> > -----------------------------------------------------------
> > 152495 default_idle 3176.9792
> > -----------------------------------------------------------
> > the above line indicates, more than 100% of times CPU is idle. This cannot
> > happen.
>
> It is not a percentage. The value is computed by:
>
> "load" = ticks_attributed_to_the_proc / length_of_proc
>
> >From your example above:
>
> 3176.9792 = 152495 / length_of_proc
>
> therefore length_of_proc = 48 bytes. 48 looks reasonable when cross
> checked with my x86 system (default_idle() is 52 bytes long on my
> system).
>
>
> > What value of the procedure load is considered to be a potential CPU
> > intensive procedure/ high load procedure.
>
> There is no magic number. However, from the readprofile man page, some
> likely "high load" candidates could be found by:
>
> readprofile | sort -nr +2 | head -20
>
>
> Regards,
> Andy
>
>
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