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From: Leonardo Bras <leobras.c@gmail.com>
To: David Gibson <david@gibson.dropbear.id.au>
Cc: Nathan Lynch <nathanl@linux.ibm.com>,
	David Hildenbrand <david@redhat.com>,
	Scott Cheloha <cheloha@linux.ibm.com>,
	linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org,
	Nicholas Piggin <npiggin@gmail.com>,
	Bharata B Rao <bharata@linux.ibm.com>,
	Paul Mackerras <paulus@samba.org>,
	Sandipan Das <sandipan@linux.ibm.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Laurent Dufour <ldufour@linux.ibm.com>,
	Logan Gunthorpe <logang@deltatee.com>,
	Dan Williams <dan.j.williams@intel.com>,
	Mike Rapoport <rppt@kernel.org>
Subject: Re: [PATCH 1/3] powerpc/mm/hash: Avoid resizing-down HPT on first memory hotplug
Date: Thu, 08 Apr 2021 23:16:41 -0300
Message-ID: <09c57b599f8dd95f4ff1c02b83aa093615257f2f.camel@gmail.com> (raw)
In-Reply-To: <YFg+Edy6dfmZx3lr@yekko.fritz.box>

Hello David, thanks for your feedback.

On Mon, 2021-03-22 at 17:49 +1100, David Gibson wrote:
> I don't love this approach.  Adding the extra flag at this level seems
> a bit inelegant, and it means we're passing up an easy opportunity to
> reduce our resource footprint on the host.

I understand, but trying to reduce resource footprint in host, and
mostly failing is what causes hot-add and hot-remove to take so long.

> But... maybe we'll have to do it.  I'd like to see if we can get
> things to work well enough with just the "batching" to avoid multiple
> resize attempts first.

This batching is something I had thought a lot about.
Problem is that there are a lot of generic interfaces between memory
hotplug and actually resizing HPT. I tried a simpler approach in
patches 2 & 3, so I don't touch much stuff there.

Best regards,
Leonardo Bras





  reply index

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-03-12  7:29 [PATCH 0/3] powerpc/mm/hash: Time improvements for memory hot(un)plug Leonardo Bras
2021-03-12  7:29 ` [PATCH 1/3] powerpc/mm/hash: Avoid resizing-down HPT on first memory hotplug Leonardo Bras
2021-03-22  6:49   ` David Gibson
2021-04-09  2:16     ` Leonardo Bras [this message]
2021-03-12  7:29 ` [PATCH 2/3] powerpc/mm/hash: Avoid multiple HPT resize-ups on " Leonardo Bras
2021-03-22  7:55   ` David Gibson
2021-04-09  2:51     ` Leonardo Bras
2021-04-19  5:34       ` David Gibson
2021-03-12  7:29 ` [PATCH 3/3] powerpc/mm/hash: Avoid multiple HPT resize-downs on memory hotunplug Leonardo Bras
2021-03-22 23:45   ` David Gibson
2021-04-09  3:31     ` Leonardo Bras
2021-04-19  5:37       ` David Gibson

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