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Date:      Tue, 26 Jan 1999 22:13:54 -0700
From:      Nate Williams <nate@mt.sri.com>
To:        SHUDO Kazuyuki <shudoh@muraoka.info.waseda.ac.jp>
Cc:        Tom <tom@sdf.com>, java@FreeBSD.ORG
Subject:   Re: TowerJ for FreeBSD
Message-ID:  <199901270513.WAA18478@mt.sri.com>
In-Reply-To: <199901270132.KAA26867@cafe.muraoka.info.waseda.ac.jp>
References:  <Pine.BSF.4.05.9901260851280.7314-100000@misery.sdf.com> <199901270132.KAA26867@cafe.muraoka.info.waseda.ac.jp>

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> > > > Yep, this is where FreeBSD (and less so Linux) got the crap kicked out
> > > > of it.  Linux is a bit better than ours for a couple of reaasons.
> >
> > > > 2) Our 'Green Threads' implementation uses locking that is not as
> > > >    effecient as the Linux version.  In particular, Linux kernel's have
> > > >    poll built in, and we emulate it (badly, but effectively) with some
> > > >    hacks to use select.
> 
> As above, Nate said that Linux kernels have poll built
> in so why Linux 'Green Threads' implementation is a bit
> better than FreeBSD one. This is incorrect. because,
> 
> > > JDK 1.1.7 for Linux/glibc use poll() and not
> > > select(). But glibc 2.0.7 which is used on most linux
> > > box replaces calls to poll with calls to select since
> > > Linux kernel prior to 2.1.23 doesn't have poll().
> 
> JDK on most Linux boxes don't make use of poll(). A
> system call poll() isn't used by JDK with glibc 2.0.X
> even if the Linux kernel has it. Poll() is being
> emulated also on Linux boxes.

I suspect the boxes that use select aren't the ones being used in the
benchmark tests.  According to what I've heard, they got much faster
performance when they did some poll tests (vs. select).

And, as I originally stated, that is just *one* reason it's faster.


Nate

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