[MPlayer-dev-eng] [PATCH] use pthreads for caching

[Rich Felker]

On Sat, Jan 27, 2007 at 10:32:54AM +0100, Diego Biurrun wrote:
> Just a general remark, not a comment on the issue at hand.
> 
> On Sat, Jan 27, 2007 at 10:20:39AM +0100, A Mennucc wrote:
> > 
> > I Googled around a bit and found that NPTL is indeed quite fast: e.g.
> > http://lwn.net/Articles/10710/
> > "(NGPT) implementation beat standard Linux threads by at least a factor
> > of two in these tests. The NPTL library, however, beat NGPT by about a
> > factor of four."
> 
> IMO these kinds of numbers just shed a light on the inefficiency of the
> old implementation rather than on the efficiency of the new one.

Yes. It's not a matter of the implementation being fast or slow. It's
fundamentally impossible to make synchronization fast. Each "lock"
prefix requires a couple hundred cycles on my machine, and I'm told
it's even worse on machines with higher clocks.

Rich