From: Zhang Zhen <zhenzhang.zhang@huawei.com>
To: David Rientjes <rientjes@google.com>
Cc: wangnan0@huawei.com, xiaofeng.yan@huawei.com, linux-mm@kvack.org
Subject: Why we echo a invalid start_address_of_new_memory succeeded ?
Date: Fri, 20 Jun 2014 15:06:42 +0800 [thread overview]
Message-ID: <53A3DD82.3070208@huawei.com> (raw)
Hi,
I am testing mem-hotplug on a qemu virtual machine. I executed the following command
to notify memory hot-add event by hand.
% echo start_address_of_new_memory > /sys/devices/system/memory/probe
To a different start_address_of_new_memory I got different results.
The results are as follows:
MBSC-x86_64 /sys/devices/system/memory # ls
block_size_bytes memory2 memory5 power
memory0 memory3 memory6 probe
memory1 memory4 memory7 uevent
MBSC-x86_64 /sys/devices/system/memory # echo 0x70000000 > probe
MBSC-x86_64 /sys/devices/system/memory # echo 0x78000000 > probe
-sh: echo: write error: File exists
MBSC-x86_64 /sys/devices/system/memory # echo 0x80000000 > probe
-sh: echo: write error: File exists
MBSC-x86_64 /sys/devices/system/memory # echo 0x88000000 > probe
-sh: echo: write error: File exists
MBSC-x86_64 /sys/devices/system/memory # echo 0x8f000000 > probe
-sh: echo: write error: Invalid argument
MBSC-x86_64 /sys/devices/system/memory # echo 0x90000000 > probe
-sh: echo: write error: File exists
MBSC-x86_64 /sys/devices/system/memory # echo 0xff0000000 > probe
MBSC-x86_64 /sys/devices/system/memory # ls
block_size_bytes memory2 memory510 probe
memory0 memory3 memory6 uevent
memory1 memory4 memory7
memory14 memory5 power
MBSC-x86_64 /sys/devices/system/memory # echo 0xfff0000000 > probe
MBSC-x86_64 /sys/devices/system/memory # ls
block_size_bytes memory2 memory510 power
memory0 memory3 memory6 probe
memory1 memory4 memory7 uevent
memory14 memory5 memory8190
The qemu virtual machine's physical memory size is 2048M, and the boot memory is 1024M.
MBSC-x86_64 / # cat /proc/meminfo
MemTotal: 1018356 kB
MBSC-x86_64 / # cat /sys/devices/system/memory/block_size_bytes
8000000
Three questions:
1. The machine's physical memory size is 2048M, why echo 0x78000000 as the start_address_of_new_memory failed ?
2. Why echo 0x8f000000 as the start_address_of_new_memory, the error message is different ?
3. Why echo 0xfff0000000 as the start_address_of_new_memory succeeded ? 0xfff0000000 has exceeded the machine's physical memory size.
Best regards!
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next reply other threads:[~2014-06-20 7:07 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2014-06-20 7:06 Zhang Zhen [this message]
2014-06-20 10:30 ` David Rientjes
2014-06-23 10:50 ` Zhang Zhen
2014-06-23 11:18 ` Zhang Zhen
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