[PATCH] Unify pthread_once (bug 15215)

[Chris Metcalf]

On 3/28/2014 7:29 PM, Carlos O'Donell wrote:
> David, Marcus, Joseph, Mike, Andreas, Steve, Chris,
>
> We would like to unify all C-based pthread_once implmentations
> per the plan in bug 15215 for glibc 2.20.
>
> Your machines are on the list of C-based pthread_once implementations.
>
> See this for the intial discussions on the unified pthread_once:
> https://sourceware.org/ml/libc-alpha/2013-05/msg00210.html

There is some performance degradation from the barriers on tilegx, but it's not terrible, and it seems like the barriers are necessary, so Ack for tile.

Before:

"pthread_once": {
"": {
"duration": 9.64547e+09, "iterations": 2.09714e+08, "max": 123.997, "min": 44.975, "mean": 45.9935
}
}

After:

"pthread_once": {
"": {
"duration": 9.69939e+09, "iterations": 1.76321e+08, "max": 165.623, "min": 54.132, "mean": 55.0099
}
}

-- 
Chris Metcalf, Tilera Corp.
http://www.tilera.com