From: Michal Hocko <mhocko@suse.com>
To: Catalin Marinas <catalin.marinas@arm.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>,
linux-mm@kvack.org, akpm@linux-foundation.org,
kirill@shutemov.name, kirill.shutemov@linux.intel.com,
vbabka@suse.cz, will.deacon@arm.com, dave.hansen@intel.com
Subject: Re: [RFC 0/4] mm: Introduce lazy exec permission setting on a page
Date: Wed, 13 Feb 2019 16:38:19 +0100 [thread overview]
Message-ID: <20190213153819.GS4525@dhcp22.suse.cz> (raw)
In-Reply-To: <20190213112135.GA9296@c02tf0j2hf1t.cambridge.arm.com>
On Wed 13-02-19 11:21:36, Catalin Marinas wrote:
> On Wed, Feb 13, 2019 at 01:36:27PM +0530, Anshuman Khandual wrote:
> > Setting an exec permission on a page normally triggers I-cache invalidation
> > which might be expensive. I-cache invalidation is not mandatory on a given
> > page if there is no immediate exec access on it. Non-fault modification of
> > user page table from generic memory paths like migration can be improved if
> > setting of the exec permission on the page can be deferred till actual use.
> > There was a performance report [1] which highlighted the problem.
> [...]
> > [1] http://lists.infradead.org/pipermail/linux-arm-kernel/2018-December/620357.html
>
> FTR, this performance regression has been addressed by commit
> 132fdc379eb1 ("arm64: Do not issue IPIs for user executable ptes"). That
> said, I still think this patch series is valuable for further optimising
> the page migration path on arm64 (and can be extended to other
> architectures that currently require I/D cache maintenance for
> executable pages).
Are there any numbers to show the optimization impact?
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2019-02-13 15:38 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-02-13 8:06 Anshuman Khandual
2019-02-13 8:06 ` [RFC 1/4] " Anshuman Khandual
2019-02-13 13:17 ` Matthew Wilcox
2019-02-13 13:53 ` Anshuman Khandual
2019-02-14 9:06 ` Mike Rapoport
2019-02-15 8:11 ` Anshuman Khandual
2019-02-15 9:49 ` Catalin Marinas
2019-02-13 8:06 ` [RFC 2/4] arm64/mm: Identify user level instruction faults Anshuman Khandual
2019-02-13 8:06 ` [RFC 3/4] arm64/mm: Allow non-exec to exec transition in ptep_set_access_flags() Anshuman Khandual
2019-02-13 8:06 ` [RFC 4/4] arm64/mm: Enable ARCH_SUPPORTS_LAZY_EXEC Anshuman Khandual
2019-02-13 11:21 ` [RFC 0/4] mm: Introduce lazy exec permission setting on a page Catalin Marinas
2019-02-13 15:38 ` Michal Hocko [this message]
2019-02-14 6:04 ` Anshuman Khandual
2019-02-14 8:38 ` Michal Hocko
2019-02-14 10:19 ` Catalin Marinas
2019-02-14 12:28 ` Michal Hocko
2019-02-15 8:45 ` Anshuman Khandual
2019-02-15 9:27 ` Michal Hocko
2019-02-18 3:07 ` Anshuman Khandual
2019-02-14 15:38 ` Dave Hansen
2019-02-18 3:19 ` Anshuman Khandual
2019-02-13 15:44 ` Dave Hansen
2019-02-14 4:12 ` Anshuman Khandual
2019-02-14 16:55 ` Dave Hansen
2019-02-18 8:31 ` Anshuman Khandual
2019-02-18 9:04 ` Catalin Marinas
2019-02-18 9:16 ` Anshuman Khandual
2019-02-18 18:20 ` Dave Hansen
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