On 12/21/2010 11:05 PM, Benjamin Herrenschmidt wrote:
So back to square 1 ... my vscsi (and virtio-blk too btw) can
technically pass a max size to the guest, but we don't have a way to
interrogate scsi-generic (and the underlying block driver) which is the
main issue (that plus the fact that
On Wed, Dec 22, 2010 at 02:54:54PM +0100, Hannes Reinecke wrote:
Most modern HBAs are using separate codepaths for streaming/block I/O
anyway,
That's not true at all. Every normal HBA justs passes normal SCSI
commands to the SCSI targets. It's just raid adapters that take special
commands,
On Wed, 2010-12-22 at 14:54 +0100, Hannes Reinecke wrote:
Well, sort of. 'sg' doesn't have any block queue limits directly as the
block queue is attached to the block device (surprise, surprise :-).
But nevertheless any commands send via SG_IO are being placed on the
block queue, hence the
On Wed, 2010-12-22 at 14:27 +0100, Christoph Hellwig wrote:
On Wed, Dec 22, 2010 at 02:54:54PM +0100, Hannes Reinecke wrote:
Most modern HBAs are using separate codepaths for streaming/block I/O
anyway,
That's not true at all. Every normal HBA justs passes normal SCSI
commands to the
On 22.12.2010, at 14:27, Christoph Hellwig wrote:
On Wed, Dec 22, 2010 at 02:54:54PM +0100, Hannes Reinecke wrote:
Most modern HBAs are using separate codepaths for streaming/block I/O
anyway,
That's not true at all. Every normal HBA justs passes normal SCSI
commands to the SCSI targets.
On 22.12.2010, at 22:59, Benjamin Herrenschmidt wrote:
On Wed, 2010-12-22 at 14:54 +0100, Hannes Reinecke wrote:
Well, sort of. 'sg' doesn't have any block queue limits directly as the
block queue is attached to the block device (surprise, surprise :-).
But nevertheless any commands send
On Thu, 2010-12-23 at 00:23 +0100, Alexander Graf wrote:
The non working compat ioctl is one, the fact that sg has
no /sys/class/block (or /sys/block) entries is another, etc... Ie,
we
are faced with a problem with Linux not exposing those informations
in
an easy to retrieve way, and no
On 23.12.2010, at 00:35, Benjamin Herrenschmidt wrote:
On Thu, 2010-12-23 at 00:23 +0100, Alexander Graf wrote:
The non working compat ioctl is one, the fact that sg has
no /sys/class/block (or /sys/block) entries is another, etc... Ie,
we
are faced with a problem with Linux not exposing
On Thu, 2010-12-23 at 00:39 +0100, Alexander Graf wrote:
This all belongs in the block layer. If you create a call back
function or property in the block struct, windows can implement its
own limits when someone sits down to implement SG_IO on Windows.
Right and we do have generic ways it
On 23.12.2010, at 00:44, Benjamin Herrenschmidt wrote:
On Thu, 2010-12-23 at 00:39 +0100, Alexander Graf wrote:
This all belongs in the block layer. If you create a call back
function or property in the block struct, windows can implement its
own limits when someone sits down to implement
On Thu, 2010-12-23 at 00:49 +0100, Alexander Graf wrote:
Congratulations for finding lots of Linux bugs :). Look at it from
that way: You'll most likely be the very first person actually using
sg properly. So after you're done, others won't have to fix it :).
Hahah, I doubt it :-) Makes me
On 12/21/2010 04:52 AM, Benjamin Herrenschmidt wrote:
On Tue, 2010-12-21 at 14:38 +1100, ronnie sahlberg wrote:
Ben,
Since it is a scsi device you can try the Inquiry command with
pagecode 0xb0 : Block Limit VPD Page.
That pages show optimal and maximum request sizes.
This is for SBC, in
So back to square 1 ... my vscsi (and virtio-blk too btw) can
technically pass a max size to the guest, but we don't have a way to
interrogate scsi-generic (and the underlying block driver) which is the
main issue (that plus the fact that the ioctl seems to be broken in
compat mode for
Hi folks !
There's an odd problem I've encountered with my scsi host (basically an
powerpc vscsi compatible with IBM PAPR).
When using /dev/sg (ie, scsi-generic), there seem to be no way I can
find to retrieve the underlying driver's max request transfer size.
This can normally be obtained with
Ben,
Since it is a scsi device you can try the Inquiry command with
pagecode 0xb0 : Block Limit VPD Page.
That pages show optimal and maximum request sizes.
This is for SBC, in the Vital Product Data chapter.
Unfortunately this page is not mandatory so some devices might not
understand it.
On Tue, 2010-12-21 at 14:38 +1100, ronnie sahlberg wrote:
Ben,
Since it is a scsi device you can try the Inquiry command with
pagecode 0xb0 : Block Limit VPD Page.
That pages show optimal and maximum request sizes.
This is for SBC, in the Vital Product Data chapter.
Unfortunately
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