From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Aaron Lu <aaron.lu@intel.com>
Cc: Dave Hansen <dave.hansen@intel.com>,
Rick Edgecombe <rick.p.edgecombe@intel.com>,
Song Liu <song@kernel.org>,
linux-kernel@vger.kernel.org, linux-mm@kvack.org
Subject: Re: [RFC PATCH 0/4] x86/mm/cpa: merge small mappings whenever possible
Date: Tue, 9 Aug 2022 13:04:08 +0300 [thread overview]
Message-ID: <20220809100408.rm6ofiewtty6rvcl@box> (raw)
In-Reply-To: <20220808145649.2261258-1-aaron.lu@intel.com>
On Mon, Aug 08, 2022 at 10:56:45PM +0800, Aaron Lu wrote:
> This is an early RFC. While all reviews are welcome, reviewing this code
> now will be a waste of time for the x86 subsystem maintainers. I would,
> however, appreciate a preliminary review from the folks on the to and cc
> list. I'm posting it to the list in case anyone else is interested in
> seeing this early version.
Last time[1] I tried to merge pages back in direct mapping it lead to
substantial performance regression for some workloads. I cannot find the
report right now, but I remember it was something graphics related.
Have you done any performance evaluation?
My take away was that the merge has to be batched. Like log where changes
to direct mapping happens and come back to then and merge when the number
of changes cross some limit.
Also I don't see you handling set_memory_4k(). Huh?
[1] https://lore.kernel.org/lkml/20200416213229.19174-1-kirill.shutemov@linux.intel.com/
--
Kiryl Shutsemau / Kirill A. Shutemov
next prev parent reply other threads:[~2022-08-09 10:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2022-08-08 14:56 [RFC PATCH 0/4] x86/mm/cpa: merge small mappings whenever possible Aaron Lu
2022-08-08 14:56 ` [RFC PATCH 1/4] x86/mm/cpa: restore global bit when page is present Aaron Lu
2022-08-11 5:21 ` Hyeonggon Yoo
2022-08-11 8:16 ` Lu, Aaron
2022-08-11 11:30 ` Hyeonggon Yoo
2022-08-11 12:28 ` Aaron Lu
2022-08-08 14:56 ` [RFC PATCH 2/4] x86/mm/cpa: merge splitted direct mapping when possible Aaron Lu
2022-08-08 14:56 ` [RFC PATCH 3/4] x86/mm/cpa: add merge event counter Aaron Lu
2022-08-08 14:56 ` [TEST NOT_FOR_MERGE 4/4] x86/mm/cpa: add a test interface to split direct map Aaron Lu
2022-08-09 10:04 ` Kirill A. Shutemov [this message]
2022-08-09 14:58 ` [RFC PATCH 0/4] x86/mm/cpa: merge small mappings whenever possible Aaron Lu
2022-08-09 17:56 ` Kirill A. Shutemov
2022-08-11 4:50 ` Hyeonggon Yoo
2022-08-11 7:50 ` Lu, Aaron
2022-08-13 16:05 ` Mike Rapoport
2022-08-16 6:33 ` Aaron Lu
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