Hi,
My driver sits above the disk class driver. Can I chain multiple MDLs (from mutliple I/O requests) and send it down in one request. I have option of using IRP_MJ_READ/WRITE or IRP_MJ_SCSI. At this time I think IRP_MJ_SCSI should work fine if the port driver supports MDL chaining as the class driver just passes these IRPs down. READ and WRITE seem to use partial MDL, so I guess it will not work. A related question to that does IoBuildPartialMdl work on chained MDLs?
thx
SID
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Hi,
The Windows storage stack does not support chained MDLs.
Anyway you will need align your read/write data to sector boundary to use IRP_MJ_SCSI…
Best regards,
Valeriy Glushkov
----- Original Message -----
From: krnl_drv
To: Windows System Software Devs Interest List
Sent: Thursday, March 16, 2006 3:47 AM
Subject: [ntdev] MDL Chaining in the storage stack
Hi,
My driver sits above the disk class driver. Can I chain multiple MDLs (from mutliple I/O requests) and send it down in one request. I have option of using IRP_MJ_READ/WRITE or IRP_MJ_SCSI. At this time I think IRP_MJ_SCSI should work fine if the port driver supports MDL chaining as the class driver just passes these IRPs down. READ and WRITE seem to use partial MDL, so I guess it will not work. A related question to that does IoBuildPartialMdl work on chained MDLs?
thx
SID
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Wondering how ReadFileScatter and WriteFileGather WIN32 APIs to provide optimum performance. Is I/O manager creating multiple IRPs to satisfy these calls?
krnl_drv wrote: Hi,
My driver sits above the disk class driver. Can I chain multiple MDLs (from mutliple I/O requests) and send it down in one request. I have option of using IRP_MJ_READ/WRITE or IRP_MJ_SCSI. At this time I think IRP_MJ_SCSI should work fine if the port driver supports MDL chaining as the class driver just passes these IRPs down. READ and WRITE seem to use partial MDL, so I guess it will not work. A related question to that does IoBuildPartialMdl work on chained MDLs?
thx
SID
---------------------------------
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they work on page sized elements and so can build a single MDL.
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of krnl_drv
Sent: Wednesday, March 15, 2006 6:05 PM
To: Windows System Software Devs Interest List
Subject: Re: [ntdev] MDL Chaining in the storage stack
Wondering how ReadFileScatter and WriteFileGather WIN32 APIs to provide
optimum performance. Is I/O manager creating multiple IRPs to satisfy
these calls?
krnl_drv wrote:
Hi,
My driver sits above the disk class driver. Can I chain multiple
MDLs (from mutliple I/O requests) and send it down in one request. I
have option of using IRP_MJ_READ/WRITE or IRP_MJ_SCSI. At this time I
think IRP_MJ_SCSI should work fine if the port driver supports MDL
chaining as the class driver just passes these IRPs down. READ and WRITE
seem to use partial MDL, so I guess it will not work. A related question
to that does IoBuildPartialMdl work on chained MDLs?
thx
SID
Brings words and photos together (easily) with
PhotoMail
http:hoo.com> - it’s free and works with Yahoo! Mail. — Questions? First
check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256 To unsubscribe, visit the
List Server section of OSR Online at
http://www.osronline.com/page.cfm?name=ListServer
Yahoo! Mail
Use Photomail
http:.mail.yahoo.com> to share photos without annoying attachments. —
Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256 To unsubscribe, visit the
List Server section of OSR Online at
http://www.osronline.com/page.cfm?name=ListServer</http:></http:>