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Date:   Tue, 11 Apr 2023 03:25:12 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     kernel test robot <oliver.sang@intel.com>
Cc:     "Liam R. Howlett" <Liam.Howlett@oracle.com>,
        oe-lkp@lists.linux.dev, lkp@intel.com,
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        Linus Torvalds <torvalds@linux-foundation.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        maple-tree@lists.infradead.org,
        Suren Baghdasaryan <surenb@google.com>, stable@vger.kernel.org,
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Subject: Re: [PATCH 8/8] mm: enable maple tree RCU mode by default.
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On Tue, Apr 11, 2023 at 09:25:16AM +0800, kernel test robot wrote:
> kernel test robot noticed a -8.5% regression of stress-ng.mmapaddr.ops_per_sec on:

Assuming this is the test in question:

https://github.com/ColinIanKing/stress-ng/blob/master/stress-mmapaddr.c

then yes, this is expected.  The test calls mmap() and munmap() a lot,
and we've made those slower in order to fix a bug.

While it does take pagefaults (which is a better test than some
microbenchmarks), it only takes one pagefault per call to mmap() and
munmap(), which is not representative of real workloads.

Thanks for running the test.