Re: LL/SC benchmarking [was: Mipsel libc with LL/SC online anywhere?]

[Jun Sun <jsun@mvista.com>]

Johannes Stezenbach wrote:
> On Fri, Jul 19, 2002 at 02:38:29PM +0200, Johannes Stezenbach wrote:
> 
>>On Fri, Jul 12, 2002 at 03:04:07PM +0200, Kevin D. Kissell wrote:
>>
>>>I'm benchmarking some code that does lots of
>>>semaphores, and with the libc from the "standard"
>>>MIPS/SGI RH 7.1 distribution, those are done using
>>>sysmips, in the interest of universality.
>>
>>I'm working on a platform without LL/SC, an embedded system/SOC
>>with a NEC VR4120A CPU core. To find out the effect of sysmips
>>vs. emulated LL/SC vs. the branch-likely trick posted by
>>Kevin D. Kissell <kevink@mips.com> on Tue, 22 Jan 2002 18:16:25 +0100
>>I created an experimental patch for glibc-2.2.5 which allows
>>run-time switching of the _test_and_set() and __compare_and_swap()
>>implementation based on the presence of two "switch files" in /etc/.
> 
> ... 
> 
>>For lack of a better benchmark I used some of the examples from
>>glibc-2.2.5/linuxthreads/Examples. The numbers are from the third
>>of three successive runs of 'time exN >/dev/null'.
> 
> 
> I did some more benchmarking with a test application based on
> gtk+-directfb (http://directfb.org/). The benchmark does not
> include GUI stuff, but rather reading of lots of external data
> into internal data structures (which are GLib-2.0 GObjects).
> The test application has three threads, but nearly all processing
> is done in the main thread.
> 
> I think that the numbers are meaningful for our type of application.
> 
> sysmips:
>         real    1m19.358s
>         user    0m28.150s
>         sys     0m47.250s
> 
> LL/SC emulation:
>         real    0m41.246s
>         user    0m25.390s
>         sys     0m12.240s
> 
> branch-likely hack (hm, still without kernel patch...):
>         real    0m25.126s
>         user    0m17.240s
>         sys     0m2.310s

Johannes,

This is great stuff!  Can you explain what are "real", "user", and "sys"? 
Also, what is your initial conclusion?

Jun