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Date: Sat, 21 Sep 2002 06:48:40 +0200 (CEST)
From: Ingo Molnar <mingo@elte.hu>
Reply-To: Ingo Molnar <mingo@elte.hu>
To: Bill Huey <billh@gnuppy.monkey.org>
Cc: Ulrich Drepper <drepper@redhat.com>,
       linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [ANNOUNCE] Native POSIX Thread Library 0.1
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On Fri, 20 Sep 2002, Bill Huey wrote:

> The JVM with incremental GC is being targetted for media oriented tasks
> using the new NIO, 3d library, etc... slowness in safepoints would
> cripple it for these tasks. It's a critical item and not easily address
> by the current 1:1 model.

actually, in the previous mail i've outlined a sensible way to help
safepoints in the kernel, for the case of the 1:1 model. I'd not call that
'not easily addressed' :-)

there's an even more advanced way to expose preempted user contexts in the
1:1 model: by putting most of the the register info (which is now dumped
into the kernel stack) into a page that is also mapped into user-space.
This too introduces (constant) syscall entry/exit overhead, but can be
done if justified.

	Ingo