From: Matthew Wilcox <willy@infradead.org>
To: Peter Collingbourne <pcc@google.com>
Cc: John Hubbard <jhubbard@nvidia.com>,
"Kirill A . Shutemov" <kirill@shutemov.name>,
Andrew Morton <akpm@linux-foundation.org>,
Catalin Marinas <catalin.marinas@arm.com>,
Evgenii Stepanov <eugenis@google.com>,
Linux ARM <linux-arm-kernel@lists.infradead.org>,
linux-mm@kvack.org
Subject: Re: [PATCH v2] mm: introduce reference pages
Date: Thu, 13 Aug 2020 23:31:22 +0100 [thread overview]
Message-ID: <20200813223122.GR17456@casper.infradead.org> (raw)
In-Reply-To: <20200813220937.40973-1-pcc@google.com>
On Thu, Aug 13, 2020 at 03:09:37PM -0700, Peter Collingbourne wrote:
> In order to measure the performance and RSS impact of reference pages,
> a version of this patch backported to kernel version 4.14 was tested on
> a Pixel 4 together with a modified [2] version of the Scudo allocator
> that uses reference pages to implement pattern initialization. A
> PDFium test program was used to collect the measurements like so:
>
> $ wget https://static.docs.arm.com/ddi0487/fb/DDI0487F_b_armv8_arm.pdf
> $ /system/bin/time -v ./pdfium_test --pages=1-100 DDI0487F_b_armv8_arm.pdf
>
> and the median of 100 runs measurement was taken with three variants
> of the allocator:
>
> - "anon" is the baseline (no pattern init)
> - "memset" is with pattern init of allocator pages implemented by
> initializing anonymous pages with memset
> - "refpage" is with pattern init of allocator pages implemented
> by creating reference pages
>
> All three variants are measured using the patch that I linked. "anon"
> is without the patch, "refpage" is with the patch and "memset" is
> with a previous version of the patch [3] with "#if 0" in place of
> "#if 1" in linux.cpp. The measurements are as follows:
>
> Real time (s) Max RSS (KiB)
> anon 2.237081 107088
> memset 2.252241 112180
> refpage 2.243786 107128
>
> We can see that RSS for refpage is almost the same as anon, and real
> time overhead is 44% that of memset.
Umm. These numbers aren't all /that/ compelling. memset takes 0.7%
longer than the baseline and consumes 4.8% more memory. I was expecting
better, to be honest ;-(
next prev parent reply other threads:[~2020-08-13 22:31 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-08-13 22:09 Peter Collingbourne
2020-08-13 22:20 ` Peter Collingbourne
2020-08-13 22:31 ` Matthew Wilcox [this message]
2020-08-13 23:46 ` Peter Collingbourne
2020-08-14 1:00 ` kernel test robot
2020-08-14 1:01 ` kernel test robot
2020-08-14 1:11 ` kernel test robot
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