From: David Miller <davem@davemloft.net>
To: mike.kravetz@oracle.com
Cc: sparclinux@vger.kernel.org, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, bob.picco@oracle.com,
nitin.m.gupta@oracle.com, vijay.ac.kumar@oracle.com,
julian.calaby@gmail.com, adam.buchbinder@gmail.com,
kirill.shutemov@linux.intel.com, mhocko@suse.com,
akpm@linux-foundation.org
Subject: Re: [RFC PATCH 04/14] sparc64: load shared id into context register 1
Date: Sat, 17 Dec 2016 22:14:42 -0500 (EST) [thread overview]
Message-ID: <20161217.221442.430708127662119954.davem@davemloft.net> (raw)
In-Reply-To: <1481913337-9331-5-git-send-email-mike.kravetz@oracle.com>
From: Mike Kravetz <mike.kravetz@oracle.com>
Date: Fri, 16 Dec 2016 10:35:27 -0800
> In current code, only context ID register 0 is set and used by the MMU.
> On sun4v platforms that support MMU shared context, there is an additional
> context ID register: specifically context register 1. When searching
> the TLB, the MMU will find a match if the virtual address matches and
> the ID contained in context register 0 -OR- context register 1 matches.
>
> Load the shared context ID into context ID register 1. Care must be
> taken to load register 1 after register 0, as loading register 0
> overwrites both register 0 and 1. Modify code loading register 0 to
> also load register one if applicable.
>
> Signed-off-by: Mike Kravetz <mike.kravetz@oracle.com>
You can't make these register accesses if the feature isn't being
used.
Considering the percentage of applications which will actually use
this thing, incuring the overhead of even loading the shared context
register is simply unacceptable.
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next prev parent reply other threads:[~2016-12-18 3:14 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-16 18:35 [RFC PATCH 00/14] sparc64 shared context/TLB support Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 01/14] sparc64: placeholder for needed mmu shared context patching Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 02/14] sparc64: add new fields to mmu context for shared context support Mike Kravetz
2016-12-17 7:34 ` Sam Ravnborg
2016-12-18 23:33 ` Mike Kravetz
2016-12-21 18:12 ` Sam Ravnborg
2016-12-17 7:38 ` Sam Ravnborg
2016-12-18 23:45 ` Mike Kravetz
2016-12-21 18:13 ` Sam Ravnborg
2016-12-16 18:35 ` [RFC PATCH 03/14] sparc64: routines for basic mmu shared context structure management Mike Kravetz
2016-12-18 3:07 ` David Miller
2016-12-16 18:35 ` [RFC PATCH 04/14] sparc64: load shared id into context register 1 Mike Kravetz
2016-12-17 7:45 ` Sam Ravnborg
2016-12-19 0:22 ` Mike Kravetz
2016-12-21 18:16 ` Sam Ravnborg
2016-12-18 3:14 ` David Miller [this message]
2016-12-19 0:06 ` Mike Kravetz
2016-12-20 18:33 ` David Miller
2016-12-20 20:27 ` Mike Kravetz
2016-12-21 18:17 ` Sam Ravnborg
2016-12-16 18:35 ` [RFC PATCH 05/14] sparc64: Add PAGE_SHR_CTX flag Mike Kravetz
2016-12-18 3:12 ` David Miller
2016-12-19 0:42 ` Mike Kravetz
2016-12-20 18:33 ` David Miller
2016-12-16 18:35 ` [RFC PATCH 06/14] sparc64: general shared context tsb creation and support Mike Kravetz
2016-12-17 7:53 ` Sam Ravnborg
2016-12-19 0:52 ` Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 07/14] sparc64: move COMPUTE_TAG_TARGET and COMPUTE_TSB_PTR to header file Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 08/14] sparc64: shared context tsb handling at context switch time Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 09/14] sparc64: TLB/TSB miss handling for shared context Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 10/14] mm: add shared context to vm_area_struct Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 11/14] sparc64: add routines to look for vmsa which can share context Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 12/14] mm: add mmap and shmat arch hooks for shared context Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 13/14] sparc64 mm: add shared context support to mmap() and shmat() APIs Mike Kravetz
2016-12-16 18:35 ` [RFC PATCH 14/14] sparc64: add SHARED_MMU_CTX Kconfig option Mike Kravetz
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