Any way to allow tunables to include small headers?

[Carlos O'Donell <carlos at redhat dot com>]

Siddhesh,

Title says it all. I'm seeing some duplication in the default
values for tunables and the defaults used in the structures
used to hold those values. Take for example:

sysdeps/unix/sysv/linux/x86/elision-conf.c

 33 struct elision_config __elision_aconf =
 34   { 
 35     /* How often to not attempt to use elision if a transaction aborted
 36        because the lock is already acquired.  Expressed in number of lock
 37        acquisition attempts.  */
 38     .skip_lock_busy = 3,
 39     /* How often to not attempt to use elision if a transaction aborted due
 40        to reasons other than other threads' memory accesses.  Expressed in
 41        number of lock acquisition attempts.  */
 42     .skip_lock_internal_abort = 3,
 43     /* How often we retry using elision if there is chance for the transaction
 44        to finish execution (e.g., it wasn't aborted due to the lock being
 45        already acquired.  */
 46     .retry_try_xbegin = 3,
 47     /* Same as SKIP_LOCK_INTERNAL_ABORT but for trylock.  */
 48     .skip_trylock_internal_abort = 3,
 49   };

elf/dl-tunables.list:

 97   elision {
 98     enable {
 99       type: INT_32
100       minval: 0
101       maxval: 1
102     }
103     skip_lock_busy {
104       type: INT_32
105       default: 3
106     }
107     skip_lock_internal_abort {
108       type: INT_32
109       default: 3
110     }
111     skip_lock_after_retries {
112       type: INT_32
113       default: 3
114     }
115     tries {
116       type: INT_32
117       default: 3
118     }
119     skip_trylock_internal_abort {
120       type: INT_32
121       default: 3
122     }
123   }

Any ideas to avoid this duplication?

I was thinking a micro-header that defines just the defaults, and we
use it in C code and the tunables list file. That would mean allowing
a include to pass through scripts/gen-tunables.awk and that could set
dangerous precedent :-)

-- 
Cheers,
Carlos.