> I think you're reffering to me here.
I don't think I am.
However, it's worth pointing out that claiming 5% for a heavily
optimised system can be shown to be a .... _highly_ arbitrary and from
the quasi-anecdotal results just posted, very unfair assertion.
We had a discussion about "Java" a while back... and some people made a
big stink about using Gentoo in a production system, and while the
distro itself is of trivial import, I think the argument that says
"optimising gets you very little on 'modern CPUs'" is in fact, the exact
corollary of the facts. Clearly, optimisation, can get you huge
performance increases, probably not ordinarily in line with HT-P4, but,
non-trivial gains all the same.
> How much time do your production systems spend compiling?
I don't think that's relevant... how much time do my production servers
spend under high system load, is a better question.
Hopefully not enough, to negate the ability to deal with a load spike,
but, not so little as to be over spec'd.
>How much time do they spend in IO? How much time do they spend on
>non-threaded apps?
Hold on a second.. I'm fairly sure we decided yesterday, that
non-threaded applications would benefit from HT. There is no way a Hyper
Thread CPU can know if it's dealing with a kernel thread, a process or a
user-space thread... unless I'm very, very wrong... to the CPU, it's
just an execution context. Perhaps the kernel knows better and only
schedules threaded applications for a Virtual CPU... but, again, I think
we decided yesterday, that CPU=Virutal CPU, thread=process, ergo, it
doesn't matter, if your application is threaded or not, hyperthreadding
_is_ a win.
>Incidentally, are you *still* not running Gentoo on any production
>systems?
Just on the one and my laptop. You'll appreciate it's not the distro,
which I'd espouse, rather, the logic that optimising as "close to the
iron" as possible _always_, _has_ to make sense... otherwise, why bother
getting a new CPU... just get a cooling kit made out of liquid nitrogen
(or similar) and overclock that p100....
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