From: Will Deacon <will@kernel.org>
To: Kalesh Singh <kaleshsingh@google.com>
Cc: surenb@google.com, minchan@google.com, joelaf@google.com,
lokeshgidra@google.com, kernel-team@android.com,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Catalin Marinas <catalin.marinas@arm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Thomas Gleixner <tglx@linutronix.de>,
Ingo Molnar <mingo@redhat.com>, Borislav Petkov <bp@alien8.de>,
x86@kernel.org, "H. Peter Anvin" <hpa@zytor.com>,
Shuah Khan <shuah@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Kees Cook <keescook@chromium.org>,
"Aneesh Kumar K.V" <aneesh.kumar@linux.ibm.com>,
Sami Tolvanen <samitolvanen@google.com>,
Masahiro Yamada <masahiroy@kernel.org>,
Josh Poimboeuf <jpoimboe@redhat.com>,
Frederic Weisbecker <frederic@kernel.org>,
Krzysztof Kozlowski <krzk@kernel.org>,
Hassan Naveed <hnaveed@wavecomp.com>,
Arnd Bergmann <arnd@arndb.de>,
Christian Brauner <christian.brauner@ubuntu.com>,
Anshuman Khandual <anshuman.khandual@arm.com>,
Mark Brown <broonie@kernel.org>, Gavin Shan <gshan@redhat.com>,
Mike Rapoport <rppt@kernel.org>,
Steven Price <steven.price@arm.com>, Jia He <justin.he@arm.com>,
John Hubbard <jhubbard@nvidia.com>,
Mike Kravetz <mike.kravetz@oracle.com>,
Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
Ram Pai <linuxram@us.ibm.com>,
Mina Almasry <almasrymina@google.com>,
Ralph Campbell <rcampbell@nvidia.com>,
Sandipan Das <sandipan@linux.ibm.com>,
Dave Hansen <dave.hansen@intel.com>,
Masami Hiramatsu <mhiramat@kernel.org>,
Jason Gunthorpe <jgg@ziepe.ca>, Brian Geffon <bgeffon@google.com>,
SeongJae Park <sjpark@amazon.de>,
linux-kernel@vger.kernel.org,
linux-arm-kernel@lists.infradead.org, linux-mm@kvack.org,
linux-kselftest@vger.kernel.org
Subject: Re: [PATCH v4 2/5] arm64: mremap speedup - Enable HAVE_MOVE_PMD
Date: Thu, 15 Oct 2020 11:55:43 +0100 [thread overview]
Message-ID: <20201015105542.GA5110@willie-the-truck> (raw)
In-Reply-To: <20201014005320.2233162-3-kaleshsingh@google.com>
On Wed, Oct 14, 2020 at 12:53:07AM +0000, Kalesh Singh wrote:
> HAVE_MOVE_PMD enables remapping pages at the PMD level if both the
> source and destination addresses are PMD-aligned.
>
> HAVE_MOVE_PMD is already enabled on x86. The original patch [1] that
> introduced this config did not enable it on arm64 at the time because
> of performance issues with flushing the TLB on every PMD move. These
> issues have since been addressed in more recent releases with
> improvements to the arm64 TLB invalidation and core mmu_gather code as
> Will Deacon mentioned in [2].
>
> From the data below, it can be inferred that there is approximately
> 8x improvement in performance when HAVE_MOVE_PMD is enabled on arm64.
>
> --------- Test Results ----------
>
> The following results were obtained on an arm64 device running a 5.4
> kernel, by remapping a PMD-aligned, 1GB sized region to a PMD-aligned
> destination. The results from 10 iterations of the test are given below.
> All times are in nanoseconds.
>
> Control HAVE_MOVE_PMD
>
> 9220833 1247761
> 9002552 1219896
> 9254115 1094792
> 8725885 1227760
> 9308646 1043698
> 9001667 1101771
> 8793385 1159896
> 8774636 1143594
> 9553125 1025833
> 9374010 1078125
>
> 9100885.4 1134312.6 <-- Mean Time in nanoseconds
>
> Total mremap time for a 1GB sized PMD-aligned region drops from
> ~9.1 milliseconds to ~1.1 milliseconds. (~8x speedup).
>
> [1] https://lore.kernel.org/r/20181108181201.88826-3-joelaf@google.com
> [2] https://www.mail-archive.com/linuxppc-dev@lists.ozlabs.org/msg140837.html
>
> Signed-off-by: Kalesh Singh <kaleshsingh@google.com>
> Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
> Cc: Catalin Marinas <catalin.marinas@arm.com>
> Cc: Will Deacon <will@kernel.org>
> Cc: Andrew Morton <akpm@linux-foundation.org>
> ---
> Changes in v4:
> - Add Kirill's Acked-by.
Argh, I thought we already enabled this for PMDs back in 2018! Looks like
that we forgot to actually do that after I improved the performance of
the TLB invalidation.
I'll pick this one patch up for 5.10.
Will
next prev parent reply other threads:[~2020-10-15 10:55 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-10-14 0:53 [PATCH v4 0/5] Speed up mremap on large regions Kalesh Singh
2020-10-14 0:53 ` [PATCH v4 1/5] kselftests: vm: Add mremap tests Kalesh Singh
2020-10-14 19:02 ` Kalesh Singh
2020-10-14 0:53 ` [PATCH v4 2/5] arm64: mremap speedup - Enable HAVE_MOVE_PMD Kalesh Singh
2020-10-15 10:55 ` Will Deacon [this message]
2020-10-14 0:53 ` [PATCH v4 3/5] mm: Speedup mremap on 1GB or larger regions Kalesh Singh
2020-12-17 17:28 ` Guenter Roeck
2020-12-17 18:15 ` Kalesh Singh
2020-10-14 0:53 ` [PATCH v4 4/5] arm64: mremap speedup - Enable HAVE_MOVE_PUD Kalesh Singh
2020-10-14 0:53 ` [PATCH v4 5/5] x86: " Kalesh Singh
2020-10-14 15:53 ` Ingo Molnar
2020-10-15 20:40 ` [PATCH v4 0/5] Speed up mremap on large regions Will Deacon
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