From: Leonardo Bras <leobras.c@gmail.com>
To: Michael Ellerman <mpe@ellerman.id.au>,
Benjamin Herrenschmidt <benh@kernel.crashing.org>,
Paul Mackerras <paulus@samba.org>,
Andrew Morton <akpm@linux-foundation.org>,
Leonardo Bras <leobras.c@gmail.com>,
Sandipan Das <sandipan@linux.ibm.com>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Logan Gunthorpe <logang@deltatee.com>,
Mike Rapoport <rppt@kernel.org>,
Bharata B Rao <bharata@linux.ibm.com>,
Dan Williams <dan.j.williams@intel.com>,
Nicholas Piggin <npiggin@gmail.com>,
Nathan Lynch <nathanl@linux.ibm.com>,
David Hildenbrand <david@redhat.com>,
Laurent Dufour <ldufour@linux.ibm.com>,
Scott Cheloha <cheloha@linux.ibm.com>,
David Gibson <david@gibson.dropbear.id.au>
Cc: linuxppc-dev@lists.ozlabs.org, linux-kernel@vger.kernel.org
Subject: [PATCH 0/3] powerpc/mm/hash: Time improvements for memory hot(un)plug
Date: Fri, 12 Mar 2021 04:29:38 -0300 [thread overview]
Message-ID: <20210312072940.598696-1-leobras.c@gmail.com> (raw)
This patchset intends to reduce time needed for processing memory
hotplug/hotunplug in hash guests.
The first one, makes sure guests with pagesize over 4k don't need to
go through HPT resize-downs after memory hotplug.
The second and third patches make hotplug / hotunplug perform a single
HPT resize per operation, instead of one for each shift change, or one
for each LMB in case of resize-down error.
Why haven't the same mechanism used for both memory hotplug and hotunplug?
They both have different requirements:
Memory hotplug causes (usually) HPT resize-ups, which are fine happening
at the start of hotplug, but resize-ups should not ever be disabled, as
other mechanisms may try to increase memory, hitting issues with a HPT
that is too small.
Memory hotunplug causes HPT resize-downs, which can be disabled (HPT will
just remain larger for a while), but need to happen at the end of an
hotunplug operation. If we want to batch it, we need to disable
resize-downs and perform it only at the end.
Tests done with this patchset in the same machine / guest config:
Starting memory: 129GB, DIMM: 256GB
Before patchset: hotplug = 710s, hotunplug = 621s.
After patchset: hotplug = 21s, hotunplug = 100s.
Any feedback will be appreciated!
I believe the code may not be very well placed in available files,
so please give some feedback on that.
Best regards,
Leonardo Bras (3):
powerpc/mm/hash: Avoid resizing-down HPT on first memory hotplug
powerpc/mm/hash: Avoid multiple HPT resize-ups on memory hotplug
powerpc/mm/hash: Avoid multiple HPT resize-downs on memory hotunplug
arch/powerpc/include/asm/book3s/64/hash.h | 4 +
arch/powerpc/include/asm/sparsemem.h | 4 +
arch/powerpc/mm/book3s64/hash_utils.c | 78 +++++++++++++++----
arch/powerpc/mm/book3s64/pgtable.c | 18 +++++
.../platforms/pseries/hotplug-memory.c | 22 ++++++
5 files changed, 111 insertions(+), 15 deletions(-)
--
2.29.2
next reply other threads:[~2021-03-12 7:32 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-03-12 7:29 Leonardo Bras [this message]
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
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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