Re: [boost] A fast-pathed rw-mutex algorithm for Boost...

From: Anthony Williams (anthony_w.geo_at_[hidden])
Date: 2006-10-27 09:04:17

"Peter Dimov" <pdimov_at_[hidden]> writes:

> Peter Dimov wrote:
>> Howard Hinnant wrote:
>
>>> So the fast path would check these bits and avoid the notify_all if
>>> they weren't set.
>>
>> Thanks, I'll try this tomorrow. Later today, I mean.
>
> Works splendidly on uniprocessor, but displays the same odd behavior I've 
> been seeing with the other algorithms on my Pentium D (with XP64):
>
> 0R+4W+0F: 46
> 0R+0W+4F: 14
> 0R+4W+4F: 10 (!)
>
> The Windows scheduler doesn't like us. Or I've made a mistake somewhere. 
> Even if I didn't, it seems to me that the bit doesn't help in the 4W case 
> since there's always a writer waiting, so we hit the notify_all.

Which mutex/condition implementation are you using? RC-1.34/HEAD/1.33.1 or
thread_rewrite?

You might get different timings with each, as the underlying mechanisms are
quite different.

Anthony
-- 
Anthony Williams
Software Developer
Just Software Solutions Ltd
http://www.justsoftwaresolutions.co.uk