What is the maximum DMA transfersize for the HBA supportig scatter/gather? I
noticed in some of the DDK sample code is set to only 128k. Don’t know why.
Is this the maximum we can set to?
Thanks,
Shakeel.
It is limited by MaximumSGList being a byte -> ( 255 - 1 ) pages -> a bit
lesser then 1MB.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “shakeel”
Newsgroups: ntdev
To: “Windows System Software Devs Interest List”
Sent: Saturday, April 03, 2004 1:00 AM
Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128k
> What is the maximum DMA transfersize for the HBA supportig scatter/gather? I
> noticed in some of the DDK sample code is set to only 128k. Don’t know why.
> Is this the maximum we can set to?
>
> Thanks,
> Shakeel.
>
>
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
Don’t think that is an issue. The PORT_CONFIGURATION_INFORMATION structure
shows ULONG
ULONG MaximumTransferLength;
ULONG NumberOfPhysicalBreaks;
Thanks,
Shakeel.
“Maxim S. Shatskih” wrote in message
news:xxxxx@ntdev…
> It is limited by MaximumSGList being a byte -> ( 255 - 1 ) pages -> a
bit
> lesser then 1MB.
>
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
>
> ----- Original Message -----
> From: “shakeel”
> Newsgroups: ntdev
> To: “Windows System Software Devs Interest List”
> Sent: Saturday, April 03, 2004 1:00 AM
> Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128k
>
>
> > What is the maximum DMA transfersize for the HBA supportig
scatter/gather? I
> > noticed in some of the DDK sample code is set to only 128k. Don’t know
why.
> > Is this the maximum we can set to?
> >
> > Thanks,
> > Shakeel.
> >
> >
> >
> > —
> > Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> > To unsubscribe send a blank email to xxxxx@lists.osr.com
>
>
> -----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of shakeel
Sent: Friday, April 02, 2004 4:01 PM
To: Windows System Software Devs Interest List
Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128kWhat is the maximum DMA transfersize for the HBA supportig
scatter/gather? I noticed in some of the DDK sample code is
set to only 128k. Don’t know why.
Is this the maximum we can set to?
That depends on your hardware. NT won’t do more than 64M and the filesystems
won’t be sending you chunks that large anyhow.
=====================
Mark Roddy
Windows .NET/XP/2000 Consulting
Hollis Technology Solutions 603-321-1032
www.hollistech.com
Mark, our HBA can take upto 8MB.
Thanks,
Shakeel.
“Mark Roddy” wrote in message news:xxxxx@ntdev…
>
>
> > -----Original Message-----
> > From: xxxxx@lists.osr.com
> > [mailto:xxxxx@lists.osr.com] On Behalf Of shakeel
> > Sent: Friday, April 02, 2004 4:01 PM
> > To: Windows System Software Devs Interest List
> > Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128k
> >
> > What is the maximum DMA transfersize for the HBA supportig
> > scatter/gather? I noticed in some of the DDK sample code is
> > set to only 128k. Don’t know why.
> > Is this the maximum we can set to?
> >
>
> That depends on your hardware. NT won’t do more than 64M and the
filesystems
> won’t be sending you chunks that large anyhow.
>
> =====================
> Mark Roddy
> Windows .NET/XP/2000 Consulting
> Hollis Technology Solutions 603-321-1032
> www.hollistech.com
>
>
>
>
I thought MaximumSGList meant number of Scatter gather entries. If yes, couldnt we have an entry which has multiple physically contiguous pages i.e. more than one page?
-----Original Message-----
From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
Sent: Friday, April 02, 2004 1:15 PM
To: Windows System Software Devs Interest List
Subject: Re: [ntdev] problems with SCSI miniport DMA transfer size > 128k
It is limited by MaximumSGList being a byte -> ( 255 - 1 ) pages -> a bit
lesser then 1MB.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “shakeel”
Newsgroups: ntdev
To: “Windows System Software Devs Interest List”
Sent: Saturday, April 03, 2004 1:00 AM
Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128k
> What is the maximum DMA transfersize for the HBA supportig scatter/gather? I
> noticed in some of the DDK sample code is set to only 128k. Don’t know why.
> Is this the maximum we can set to?
>
> Thanks,
> Shakeel.
>
>
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
—
Questions? First check the Kernel Driver FAQ at http://www.osronline.com/article.cfm?id=256
You are currently subscribed to ntdev as: xxxxx@troikanetworks.com
To unsubscribe send a blank email to xxxxx@lists.osr.com
Is this limitation due to not getting more than 4K(Page size) of uncached
Physical contiguous memory to build the scatter/gather list?
DDK documentation says that the miniport can request upto or less than 100k
of uncached memory by calling ScsiPortGetUncachedExtension() once in
hwscsifindadapter() routine.
Is there way to get more than 4K of uncached contigous physical memory.
Thanks,
“Mukul Kotwani” wrote in message
news:xxxxx@ntdev…
I thought MaximumSGList meant number of Scatter gather entries. If yes,
couldnt we have an entry which has multiple physically contiguous pages i.e.
more than one page?
-----Original Message-----
From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
Sent: Friday, April 02, 2004 1:15 PM
To: Windows System Software Devs Interest List
Subject: Re: [ntdev] problems with SCSI miniport DMA transfer size > 128k
It is limited by MaximumSGList being a byte -> ( 255 - 1 ) pages -> a
bit
lesser then 1MB.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “shakeel”
Newsgroups: ntdev
To: “Windows System Software Devs Interest List”
Sent: Saturday, April 03, 2004 1:00 AM
Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128k
> What is the maximum DMA transfersize for the HBA supportig scatter/gather?
I
> noticed in some of the DDK sample code is set to only 128k. Don’t know
why.
> Is this the maximum we can set to?
>
> Thanks,
> Shakeel.
>
>
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
—
Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
You are currently subscribed to ntdev as: xxxxx@troikanetworks.com
To unsubscribe send a blank email to xxxxx@lists.osr.com
You could in theory. There are two problems.
1 - MaximumSGList doesn’t ever specify how big a segment a single SG
list entry could describe. For some cards this could be 4GB, for others
it could be as little as a single page. The only safe assumption is a
single page.
2 - the Class driver is the one that does the request fragmentation
based on the MaximumSGList entries of the controller and the maximum
transfer size. The class driver doesn’t know how fragmented the request
is and thus assumes each page will require a separate SG entry. Again
it’s not the best decision that could be made, but it’s the safe one.
In general physical memory is pretty fragmented so it’s also right a lot
of the time.
The result is that MaximumSGList is the equivalent of max pages.
-p
-----Original Message-----
From: xxxxx@lists.osr.com
[mailto:xxxxx@lists.osr.com] On Behalf Of Mukul Kotwani
Sent: Friday, April 02, 2004 4:46 PM
To: Windows System Software Devs Interest List
Subject: RE: [ntdev] problems with SCSI miniport DMA transfer size >
128k
I thought MaximumSGList meant number of Scatter gather entries. If yes,
couldnt we have an entry which has multiple physically contiguous pages
i.e. more than one page?
-----Original Message-----
From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
Sent: Friday, April 02, 2004 1:15 PM
To: Windows System Software Devs Interest List
Subject: Re: [ntdev] problems with SCSI miniport DMA transfer size >
128k
It is limited by MaximumSGList being a byte -> ( 255 - 1 ) pages ->
a bit lesser then 1MB.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “shakeel”
Newsgroups: ntdev
To: “Windows System Software Devs Interest List”
Sent: Saturday, April 03, 2004 1:00 AM
Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128k
> What is the maximum DMA transfersize for the HBA supportig
scatter/gather? I
> noticed in some of the DDK sample code is set to only 128k. Don’t know
why.
> Is this the maximum we can set to?
>
> Thanks,
> Shakeel.
>
>
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
—
Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
You are currently subscribed to ntdev as: xxxxx@troikanetworks.com
To unsubscribe send a blank email to xxxxx@lists.osr.com
—
Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
You are currently subscribed to ntdev as: xxxxx@windows.microsoft.com
To unsubscribe send a blank email to xxxxx@lists.osr.com
So what? The MaximumSGList is limited to 255 nevertheless.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “shakeel”
Newsgroups: ntdev
To: “Windows System Software Devs Interest List”
Sent: Saturday, April 03, 2004 2:25 AM
Subject: Re:[ntdev] problems with SCSI miniport DMA transfer size > 128k
> Don’t think that is an issue. The PORT_CONFIGURATION_INFORMATION structure
> shows ULONG
> ULONG MaximumTransferLength;
> ULONG NumberOfPhysicalBreaks;
>
> Thanks,
> Shakeel.
>
>
> “Maxim S. Shatskih” wrote in message
> news:xxxxx@ntdev…
> > It is limited by MaximumSGList being a byte -> ( 255 - 1 ) pages -> a
> bit
> > lesser then 1MB.
> >
> > Maxim Shatskih, Windows DDK MVP
> > StorageCraft Corporation
> > xxxxx@storagecraft.com
> > http://www.storagecraft.com
> >
> >
> > ----- Original Message -----
> > From: “shakeel”
> > Newsgroups: ntdev
> > To: “Windows System Software Devs Interest List”
> > Sent: Saturday, April 03, 2004 1:00 AM
> > Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128k
> >
> >
> > > What is the maximum DMA transfersize for the HBA supportig
> scatter/gather? I
> > > noticed in some of the DDK sample code is set to only 128k. Don’t know
> why.
> > > Is this the maximum we can set to?
> > >
> > > Thanks,
> > > Shakeel.
> > >
> > >
> > >
> > > —
> > > Questions? First check the Kernel Driver FAQ at
> > http://www.osronline.com/article.cfm?id=256
> > >
> > > You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> > > To unsubscribe send a blank email to xxxxx@lists.osr.com
> >
> >
>
>
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
From what I know, SCSIPORT accounts for worst-case scenario of maximum
fragmentation, and thus MaximumSGList is the number of pages.
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
xxxxx@storagecraft.com
http://www.storagecraft.com
----- Original Message -----
From: “Mukul Kotwani”
To: “Windows System Software Devs Interest List”
Sent: Saturday, April 03, 2004 4:46 AM
Subject: RE: [ntdev] problems with SCSI miniport DMA transfer size > 128k
>
> I thought MaximumSGList meant number of Scatter gather entries. If yes,
couldnt we have an entry which has multiple physically contiguous pages i.e.
more than one page?
>
>
> -----Original Message-----
> From: Maxim S. Shatskih [mailto:xxxxx@storagecraft.com]
> Sent: Friday, April 02, 2004 1:15 PM
> To: Windows System Software Devs Interest List
> Subject: Re: [ntdev] problems with SCSI miniport DMA transfer size > 128k
>
>
> It is limited by MaximumSGList being a byte -> ( 255 - 1 ) pages -> a bit
> lesser then 1MB.
>
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> xxxxx@storagecraft.com
> http://www.storagecraft.com
>
>
> ----- Original Message -----
> From: “shakeel”
> Newsgroups: ntdev
> To: “Windows System Software Devs Interest List”
> Sent: Saturday, April 03, 2004 1:00 AM
> Subject: [ntdev] problems with SCSI miniport DMA transfer size > 128k
>
>
> > What is the maximum DMA transfersize for the HBA supportig scatter/gather?
I
> > noticed in some of the DDK sample code is set to only 128k. Don’t know why.
> > Is this the maximum we can set to?
> >
> > Thanks,
> > Shakeel.
> >
> >
> >
> > —
> > Questions? First check the Kernel Driver FAQ at
> http://www.osronline.com/article.cfm?id=256
> >
> > You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> > To unsubscribe send a blank email to xxxxx@lists.osr.com
>
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@troikanetworks.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>
> —
> Questions? First check the Kernel Driver FAQ at
http://www.osronline.com/article.cfm?id=256
>
> You are currently subscribed to ntdev as: xxxxx@storagecraft.com
> To unsubscribe send a blank email to xxxxx@lists.osr.com
>