Re: syscalls performance

[Enrico Granata <egranata@xxxxxxxx>]

Attachment: syscallperf.c
Description: Binary data

I modified the source code to show exactly how many clock ticks it is taking for each call. It seems that the behavior hinted by Mauro Romano Trajber is actually there:

[enrico@espresso ~]$ ./syscallperf 15

4925

1190

942

942

935

942

636

577

627

621

580

591

565

580

565

I am starting to wonder if this depends on the syscall itself OR on some call optimization.. any gcc experts around?

Enrico Granata

Computer Science & Engineering Department (EBU3B) - Room 3240

office phone 858 534 9914

University of California, San Diego

On Feb 25, 2011, at 12:30 PM, Mauro Romano Trajber wrote:

Sure, the code is attached.

On Fri, Feb 25, 2011 at 5:15 PM, Daniel Baluta <daniel.baluta@xxxxxxxxx> wrote:

On Fri, Feb 25, 2011 at 8:22 PM, Mauro Romano Trajber <trajber@xxxxxxxxx> wrote:
> Thanks Enrico and Daniel, you're right. glibc was caching getpid(); but this
> is not the root cause of this behavior.
> Going further, I decide to use call getpid without glibc, using
>  syscall(SYS_getpid) to test this behavior and it happened again.
> Calling it once, the test consumes about 7k CPU cycles and 10 calls consumes
> about 10k CPU cycles.
> Any ideas ?

Can you post a pointer to your code and information about how you got
this numbers?

thanks,
Daniel.

<syscallperf.c>

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