Re: [RFC] libstdc++ atomicity, x86 agnostic version

[Gabriel Dos Reis <gdr at integrable-solutions dot net>]

Paolo Carlini <pcarlini@suse.de> writes:

| Gabriel Dos Reis wrote:
| 
| >Why not just ditch that ref from foo()?
| >
| Yeah, thanks Gaby for you feedback.
| I already did that and tried to simulate the overall effect of Benjamin's
| work by simply removing the inline keywork from the current
| __exchange_and_add and __atomic_add.
| 
| These are the numbers (-O2, P4-2400) (Jakub_am is without the &)
| 
| current
| =======
| Jakub (50000000 iters)
| 5.590u 0.000s 0:05.74 97.3%     0+0k 0+0io 160pf+0w
| 
| Jakub_am (50000000)
| 11.250u 0.000s 0:11.57 97.2%    0+0k 0+0io 160pf+0w
| 
| patched
| =======
| Jakub (50000000)
| 6.370u 0.000s 0:06.55 97.2%     0+0k 0+0io 162pf+0w
| 
| Jakub_am (50000000)
| 12.600u 0.000s 0:12.96 97.2%    0+0k 0+0io 162pf+0w
| 
| So, for this kind of testcase, on the x86 architecture, is a loss of
| about 10-12%.
| 
| I don't know if we want to live with that... Gaby? Opinions?

This whole ref-count string stuff is always an endless source of
issues.  I would not be able to actively follow any discussion this
morning (not even have time to read mails); so adopt whatever
short-time solution makes Benjamin and the RM happy AND point out what
the long-term solution should be (preferably fill a PR).

Having a slow string implementation is a bummer :-(

-- Gaby