Proposal for adding O_DIRECT support into JDK 9

[Lu, Yingqi]

Hi All,

Just want to check if there is any other feedback on the most recent DirectIO patch which is available at http://cr.openjdk.java.net/~kkharbas/8164900/webrev.04/

Thanks,
Lucy

>-----Original Message-----
>From: nio-dev [mailto:nio-dev-bounces at openjdk.java.net] On Behalf Of Lu,
>Yingqi
>Sent: Thursday, November 17, 2016 9:06 AM
>To: Philippe Marschall <philippe.marschall at gmail.com>; nio-
>dev at openjdk.java.net
>Cc: David Holmes <david.holmes at oracle.com>; Kaczmarek, Eric
><eric.kaczmarek at intel.com>; Thomas Stüfe <thomas.stuefe at gmail.com>;
>Kharbas, Kishor <kishor.kharbas at intel.com>
>Subject: RE: Proposal for adding O_DIRECT support into JDK 9
>
>Hi Philippe,
>
>Thank you very much for your feedback. We can certainly change
>FileStore.getBlockSize to default method. We will make this modification into our
>next version of the patch.
>
>All,
>
>Besides this change, do you have any other feedback and comments?
>
>Thanks,
>Lucy
>
>>-----Original Message-----
>>From: Philippe Marschall [mailto:philippe.marschall at gmail.com]
>>Sent: Thursday, November 17, 2016 6:02 AM
>>To: nio-dev at openjdk.java.net
>>Cc: Alan Bateman <Alan.Bateman at oracle.com>; Lu, Yingqi
>><yingqi.lu at intel.com>; Kharbas, Kishor <kishor.kharbas at intel.com>;
>>David Holmes <david.holmes at oracle.com>; Thomas Stüfe
>><thomas.stuefe at gmail.com>; Kaczmarek, Eric <eric.kaczmarek at intel.com>
>>Subject: Re: Proposal for adding O_DIRECT support into JDK 9
>>
>>Hi
>>
>>I'm just a lurker so excuse me when overstep some boundaries here.
>>Assuming FileStore#getBlockSize stays:
>>- Could that be changed into a default method? That would be a help for
>>any file system implementer (eg myself) and would also simplify
>>JrtFileStore and ZipFileStore.
>>- Could the Javadoc be updated to state that throwing
>>UnsupportedOperationException is valid?
>>
>>Cheers
>>Philippe
>>
>>On Wed, Nov 16, 2016 at 11:14 PM, Lu, Yingqi <yingqi.lu at intel.com> wrote:
>>> Hi All,
>>>
>>>
>>>
>>> Our most recent version of our DirectIO patch is available at
>>> http://cr.openjdk.java.net/~kkharbas/8164900/webrev.04/
>>>
>>> In this version, we have modified the following items:
>>>
>>> 1.       Remove ByteBuffer.allocateDirectAligned() and
>>> ByteBuffer.isAligned(). Instead, using existing APIs
>>> alignmentOffset() and
>>> alignedSlice()
>>>
>>> 2.       Use Block Size as the alignment value instead of OS page size
>>>
>>> 3.       Create a function named getBlockSize from FileStore class
>>>
>>> 4.       Implement DirectIO for Windows
>>>
>>> 5.       JTreg test passed for Windows, Linux and OS X with regarding to the
>>> DirectIO changes we made
>>>
>>>
>>>
>>> Please let us know your comments and feedback. Thank you very much
>>> for your consideration!
>>>
>>>
>>>
>>> Thanks,
>>>
>>> Lucy
>>>
>>>
>>>
>>> From: nio-dev [mailto:nio-dev-bounces at openjdk.java.net] On Behalf Of
>>> Lu, Yingqi
>>> Sent: Sunday, November 06, 2016 9:37 AM
>>> To: Alan Bateman <Alan.Bateman at oracle.com>
>>> Cc: Kharbas, Kishor <kishor.kharbas at intel.com>; David Holmes
>>> <david.holmes at oracle.com>; core-libs-dev at openjdk.java.net;
>>> nio-dev at openjdk.java.net; Thomas Stüfe <thomas.stuefe at gmail.com>;
>>> Kaczmarek, Eric <eric.kaczmarek at intel.com>
>>> Subject: Re: Proposal for adding O_DIRECT support into JDK 9
>>>
>>>
>>>
>>> Hi Alan,
>>>
>>>
>>>
>>> Thank you very much for your suggestion. FileStore is a better home
>>> for the alignment value. We will use It in our next version of the
>>> patch and update here for review soon.
>>>
>>> Thanks,
>>>
>>> Lucy
>>>
>>> Sent from my iPhone
>>>
>>> On Nov 6, 2016, at 9:04 AM, Alan Bateman <Alan.Bateman at oracle.com>
>>wrote:
>>>
>>> On 06/11/2016 15:51, Lu, Yingqi wrote:
>>>
>>> Another approach might be use ioctl to get the block size and use
>>> that as the alignment value. I think ioctl is available on UNIX based
>>> OSes (please chime in if I miss any OS here) and has a similar call
>>> for Windows named DeviceIoControl. The request code of ioctl is
>>> different from OS to OS, but we could address that in the native code.
>>>
>>>
>>>
>>> A possible approach (I think I mentioned this in one of the early
>>> mails) is to have FileStore expose the block size that can be use to
>>> align and size the buffer.
>>>
>>> -Alan