linux-kernel - Re: [V2] android: binder: use VM

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Date:   Tue, 15 Nov 2016 21:18:33 +0800
From:   Ganesh Mahendran <opensource.ganesh@...il.com>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     linux-kernel <linux-kernel@...r.kernel.org>,
        devel@...verdev.osuosl.org,
        Arve Hjønnevåg <arve@...roid.com>,
        Riley Andrews <riandrews@...roid.com>
Subject: Re: [V2] android: binder: use VM_ALLOC to get vm area

Hi, Greg

2016-11-15 18:18 GMT+08:00 Greg KH <gregkh@...uxfoundation.org>:
> On Tue, Nov 15, 2016 at 05:55:39PM +0800, Ganesh Mahendran wrote:
>> VM_IOREMAP is used to access hardware through a mechanism called
>> I/O mapped memory. Android binder is a IPC machanism which will
>> not access I/O memory.
>>
>> Also VM_IOREMAP has alignment requiement which may not needed in
>> binder.
>>     __get_vm_area_node()
>>     {
>>     ...
>>         if (flags & VM_IOREMAP)
>>             align = 1ul << clamp_t(int, fls_long(size),
>>                PAGE_SHIFT, IOREMAP_MAX_ORDER);
>>     ...
>>     }
>>
>> This patch use VM_ALLOC to get vm area.
>>
>> Below is the throughput test result:
>>
>>   # ./binderThroughputTest -w 100
>>   I run this command 10 times:
>>                                before    after
>>   average iterations per sec:  11199.9   11886.9
>>
>> No performance regression found throgh binder test.
>>
>> Signed-off-by: Ganesh Mahendran <opensource.ganesh@...il.com>
>> ---
>>  drivers/android/binder.c | 2 +-
>>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> What changed from v1?

Sorry for missing the change information.

In V2, I run the binder test. And there is no side effect with this
patch.

>
> Always list that below the --- line.

Thanks for reminder.

>
> thanks,
>
> greg k-h