[RFC][PATCH] tunables: Add elision tunable

[Stefan Liebler]

Hi Rogerio,

On 09/13/2017 09:28 PM, rcardoso wrote:
> Hi Stefan,
> 
> Thanks for your review. I attached a v2 patch with you fix suggestions.
> 
>  >In addition to Paul's patches, here is a link to a newer patch from 
>  >Carlos:
>  >"RFC: Always-on elision with per-process opt-in using tunables."
>  >https://www.sourceware.org/ml/libc-alpha/2017-05/msg00335.html
>  >
>  >He also removes the --enable-lock-elision configure flag.
>  >Is this also required for your patch?
> 
> I'm aware of Carlos patch. In fact I talk to him before send this mail 
> since we are doing similar things. And we agree that I will send this 
> patch and he will word around with changes (like enable-lock-elision flag). >
Okay.
Please also change the order of the lines (in all elision-conf.c files):
+# include <elf/dl-tunables.h>
+# define TUNABLE_NAMESPACE elision

If TUNABLE_NAMESPACE is not defined before dl-tunables.h is included,
there will be a build error as TUNABLE_GET will require 5 instead of 
three arguments.


>  >I've also used a small s390 specific test program to check wether a 
> mutex was elided or not:
> 
> Pretty neat test. I see you already sent the test on this thread on 
> another reply. I will try to port it to power and x86 here.
>Testing the other variables is not as easy as en-/disabling lock-elision.

> Regards,
> Rogerio

Bye
Stefan