RE: [PATCH] lockref: remove cpu_relax() again

[Luck, Tony]

>> Worse still - early processor implementations actually just ignored
>> the acquire/release and did a full fence all the time.  Unfortunately
>> this meant a lot of badly written code that used .acq when they really
>> wanted .rel became legacy out in the wild - so when we made a cpu
>> that strictly did the .acq or .rel ... all that code started breaking - so
>> we had to back-pedal and keep the "legacy" behavior of a full fence :-(
>
> Ugh. Can you try what happens with the weaker release-semantics
> performance-wise for that code? Do it *just* for the lockref code..

No.  I can change the Linux code to say "cmpxchg.rel" here ... but the
h/w will do exactly the same thing it did when I had "cmpxchg.acq".

-Tony
èº{.nÇ+‰·Ÿ®‰­†+%ŠËlzwm…ébëæìr¸›zX§»®w¥Š{ayºÊÚë,j­¢f£¢·hš‹àz¹®w¥¢¸¢·¦j:+v‰¨ŠwèjØm¶Ÿÿ¾«‘êçzZ+ƒùšŽŠÝj"ú!¶iO•æ¬z·švØ^¶m§ÿðÃnÆàþY&—