From: "H. Peter Anvin" <hpa@zytor.com>
To: Jeremy Fitzhardinge <jeremy@goop.org>
Cc: Ingo Molnar <mingo@elte.hu>, LKML <linux-kernel@vger.kernel.org>,
Andi Kleen <ak@suse.de>, Jan Beulich <jbeulich@novell.com>,
Eduardo Pereira Habkost <ehabkost@redhat.com>,
Ian Campbell <ijc@hellion.org.uk>,
William Irwin <wli@holomorphy.com>,
Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: [PATCH 11 of 11] x86: defer cr3 reload when doing pud_clear()
Date: Fri, 25 Jan 2008 13:37:13 -0800 [thread overview]
Message-ID: <479A5689.80505@zytor.com> (raw)
In-Reply-To: <c084def0f6afb2b2ef47.1201296200@localhost>
Jeremy Fitzhardinge wrote:
> PAE mode requires that we reload cr3 in order to guarantee that
> changes to the pgd will be noticed by the processor. This means that
> in principle pud_clear needs to reload cr3 every time. However,
> because reloading cr3 implies a tlb flush, we want to avoid it where
> possible.
It only matters (for a processor which supports PGE) if we actually use
the namespace in between.
> In huge_pmd_unshare, it is followed by flush_tlb_range, which always
> results in a full cr3-reload tlb flush.
This one makes me nervous, as it feels like a side effect of
implementation, and not a guarantee by design.
-hpa
next prev parent reply other threads:[~2008-01-25 21:42 UTC|newest]
Thread overview: 32+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-01-25 21:23 [PATCH 00 of 11] x86: separate pmd lifetime from pgd Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 01 of 11] xen: fix mismerge in masking pte flags Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 02 of 11] x86: use the same pgd_list for PAE and 64-bit Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 03 of 11] x86: add mm parameter to paravirt_alloc_pd Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 04 of 11] x86: fix early_ioremap pagetable ops Jeremy Fitzhardinge
2008-01-31 19:01 ` Ian Campbell
2008-01-31 19:52 ` Jeremy Fitzhardinge
2008-01-31 20:37 ` Ingo Molnar
2008-01-31 20:41 ` Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 05 of 11] x86: demacro asm-x86/pgalloc_32.h Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 06 of 11] x86: unify PAE/non-PAE pgd_ctor Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 07 of 11] x86: don't special-case pmd allocations as much Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 08 of 11] xen: deal with pmd being allocated/freed Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 09 of 11] x86: preallocate pmds at pgd creation time Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 10 of 11] x86: allocate and initialize unshared pmds Jeremy Fitzhardinge
2008-01-25 21:23 ` [PATCH 11 of 11] x86: defer cr3 reload when doing pud_clear() Jeremy Fitzhardinge
2008-01-25 21:37 ` H. Peter Anvin [this message]
2008-01-25 22:54 ` Jeremy Fitzhardinge
2008-01-25 23:38 ` Keir Fraser
2008-01-25 23:44 ` Jeremy Fitzhardinge
2008-01-26 0:11 ` Ingo Molnar
2008-01-26 0:20 ` H. Peter Anvin
2008-01-26 5:57 ` Andi Kleen
2008-01-26 6:03 ` H. Peter Anvin
2008-01-26 0:10 ` H. Peter Anvin
2008-01-26 0:57 ` Jeremy Fitzhardinge
2008-01-26 1:09 ` H. Peter Anvin
2008-01-28 15:17 ` [PATCH 00 of 11] x86: separate pmd lifetime from pgd Ingo Molnar
2008-01-28 15:39 ` Jeremy Fitzhardinge
2008-01-28 15:41 ` Ingo Molnar
2008-01-28 15:47 ` Ingo Molnar
2008-01-28 16:20 ` Jeremy Fitzhardinge
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