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Date: Mon, 12 Aug 2002 19:41:12 +0200 (CEST)
From: Ingo Molnar <mingo@elte.hu>
Reply-To: Ingo Molnar <mingo@elte.hu>
To: Jakub Jelinek <jakub@redhat.com>
Cc: Linus Torvalds <torvalds@transmeta.com>, <linux-kernel@vger.kernel.org>,
       Alexandre Julliard <julliard@winehq.com>,
       Luca Barbieri <ldb@ldb.ods.org>
Subject: Re: [patch] tls-2.5.31-D5
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On Mon, 12 Aug 2002, Jakub Jelinek wrote:

> As each supported TLS entry has its context-switch time cost, I think we
> should stay at 2 supported TLS entries.

4 are almost as good - and they also solve the 0x40 problem.

> My understanding was that the GDT patches were written to optimize the
> common case (all threaded apps using LDT and with the advent of __thread
> support causing every single application to use LDT), with 2 TLS entries
> where one is for libc/libpthread and the other one is for application
> usage I think it is enough for 99.9% of apps. In the rare case someone
> needs more, there is still LDT which offers 8192 entries.

well, i think i have to agree ... if it wasnt for Wine's 0x40 descriptor.  
But it certainly does not come free. We could have 3 TLS entries (0x40
will be the last entry), and the copying cost is 9 cycles. (compared to 6
cycles in the 2 entries case.) Good enough?

	Ingo

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