From: "Huang\, Ying" <ying.huang@intel.com>
To: Mike Kravetz <mike.kravetz@oracle.com>
Cc: Michal Hocko <mhocko@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Andi Kleen <andi.kleen@intel.com>, Jan Kara <jack@suse.cz>,
Andrea Arcangeli <aarcange@redhat.com>,
"Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>,
Matthew Wilcox <mawilcox@microsoft.com>,
Hugh Dickins <hughd@google.com>, Minchan Kim <minchan@kernel.org>,
Shaohua Li <shli@fb.com>, Christopher Lameter <cl@linux.com>
Subject: Re: [PATCH -mm] mm, huge page: Copy to access sub-page last when copy huge page
Date: Mon, 21 May 2018 10:34:25 +0800 [thread overview]
Message-ID: <87bmd9ka8e.fsf@yhuang-dev.intel.com> (raw)
In-Reply-To: <64430ed4-4019-d597-ccb3-8bf6b04ee464@oracle.com> (Mike Kravetz's message of "Fri, 18 May 2018 09:41:04 -0700")
Mike Kravetz <mike.kravetz@oracle.com> writes:
> On 05/17/2018 11:24 PM, Michal Hocko wrote:
>> On Fri 18-05-18 11:03:16, Huang, Ying wrote:
>> [...]
>>> The patch is a generic optimization which should benefit quite some
>>> workloads, not for a specific use case. To demonstrate the performance
>>> benefit of the patch, we tested it with vm-scalability run on
>>> transparent huge page.
>>
>> It is also adds quite some non-intuitive code. So is this worth? Does
>> any _real_ workload benefits from the change?
>
> One way to 'add less code' would be to create a helper routine that
> indicates the order in which sub-pages are to be copied. IIUC, you
> added the same algorithm for sub-page ordering to copy_huge_page()
> that was previously added to clear_huge_page(). Correct?
Yes.
> If so, then perhaps a common helper could be used by both the clear
> and copy huge page routines. It would also make maintenance easier.
That's a good idea. But this may need to turn
copy_user_highpage()/clear_user_highpage() calling in
copy_user_huge_page()/clear_huge_page() from direct call to indirect
call. I don't know whether this will incur some overhead. Will try to
measure this.
Best Regards,
Huang, Ying
next prev parent reply other threads:[~2018-05-21 2:34 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-05-18 3:03 [PATCH -mm] mm, huge page: Copy to access sub-page last when copy huge page Huang, Ying
2018-05-18 6:24 ` Michal Hocko
2018-05-18 16:41 ` Mike Kravetz
2018-05-21 2:34 ` Huang, Ying [this message]
2018-05-21 1:51 ` Huang, Ying
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