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From: GeHao Kang <kanghao0928@gmail.com>
To: mel@csn.ul.ie
Cc: linux-mm@kvack.org
Subject: mm: Page allocation from buddy system might delay the tasks on different SMP cores
Date: Wed, 20 Apr 2016 00:07:21 +0800	[thread overview]
Message-ID: <CANv7uPRLOS1kWos4k7aNXdx_Gx72BNxHWmJyOYs=GFydV63fAQ@mail.gmail.com> (raw)

Hi Mel,
Through my experiment in SMP system, I find the mm_page_alloc_zone_locked
event produced by the fork system call on one CPU might delay the task
on another CPU.  According to the events-keme.txt in kernel documents,
the interrupts are disabled and cache lines between CPUs are dirtied
when this event happens.  Therefore, I am afraid that a task might be
interfered by the tasks on different CPUs
which at the same time request memory from the buddy allocator.

My questions are as follows:
    * Is it necessary to disable interrupts when allocating/freeing memory from
      buddy system?
    * Why the cache lines between CPUs are dirtied by the allocation in
      buddy system?

Thanks,
- Kang

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             reply	other threads:[~2016-04-19 16:07 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-04-19 16:07 GeHao Kang [this message]
2016-04-19 17:59 ` Mel Gorman

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