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Date: Tue, 14 Aug 2018 03:34:12 -0400
From: "Emilio G. Cota" <cota@braap.org>
Message-ID: <20180814073412.GA32086@flamenco>
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Subject: Re: [Qemu-devel] [PATCH 3/4] target/i386/translate: use
 thread-local storage in !user-mode
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To: Paolo Bonzini <pbonzini@redhat.com>
Cc: qemu-devel@nongnu.org, Peter Crosthwaite <crosthwaite.peter@gmail.com>, Richard Henderson <rth@twiddle.net>, Eduardo Habkost <ehabkost@redhat.com>, "Michael S . Tsirkin" <mst@redhat.com>, Marcel Apfelbaum <marcel.apfelbaum@gmail.com>, Alex =?iso-8859-1?Q?Benn=E9e?= <alex.bennee@linaro.org>

On Tue, Aug 14, 2018 at 08:31:02 +0200, Paolo Bonzini wrote:
> On 14/08/2018 03:38, Emilio G. Cota wrote:
> > Needed for MTTCG.
> > 
> > Signed-off-by: Emilio G. Cota <cota@braap.org>
> 
> Why not always use TLS, even in user-mode?

To avoid TLS waste; user-mode uses a single TCGContext,
so a single copy of these variables is all that's needed because
code generation is serialized with a lock.

If in user-mode we just have a few threads it'd be no big deal,
but apps can easily spawn thousands of threads.

		E.