Re: scsi_debug, iosize optimal < minimum

2016-02-03 Thread Martin K. Petersen 
> "Ruediger" == Ruediger Meier  writes:

Ruediger> In past (kernel<=4.1) optimal_io_size io size was 32768. Is
Ruediger> this really correct now?

We recently bumped the scsi_debug optimal I/O size to something akin to
what real-world storage reports.

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Martin K. Petersen  Oracle Linux Engineering
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Re: scsi_debug, iosize optimal < minimum

2016-02-03 Thread Ruediger Meier 
On Monday 01 February 2016, Martin K. Petersen wrote:
> > "Ruediger" == Ruediger Meier  writes:
>
> Ruediger> I've noticed a possible problem with scsi_debug devices
> where Ruediger> optimal_io_size < minimum_io_size.
>
> Ruediger> The problem seems reproducable with kernel 4.4.0 and also
> with Ruediger> stable version 4.1.15. For stable tree the last known
> working Ruediger> version is 4.1.13.
>
> http://git.kernel.org/cgit/linux/kernel/git/mkp/scsi.git/commit/?h=4.
>5/scsi-fixes&id=d0eb20a863ba7dc1d3f4b841639671f134560be2


Ah thanks!

But I'm still wondering a bit. Using kernel 4.5-rc2 (where 9c1d9c20 and 
d0eb20a8 is included) I get

$ getconf PAGESIZE
4096
$ modprobe scsi_debug
$  cat /sys/block/$devname/queue/{minimum_io_size,optimal_io_size}
512
524288

In past (kernel<=4.1) optimal_io_size io size was 32768. Is this really 
correct now?

cu,
Rudi
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Re: scsi_debug, iosize optimal < minimum

2016-02-01 Thread Martin K. Petersen 
> "Ruediger" == Ruediger Meier  writes:

Ruediger> I've noticed a possible problem with scsi_debug devices where
Ruediger> optimal_io_size < minimum_io_size.

Ruediger> The problem seems reproducable with kernel 4.4.0 and also with
Ruediger> stable version 4.1.15. For stable tree the last known working
Ruediger> version is 4.1.13.

http://git.kernel.org/cgit/linux/kernel/git/mkp/scsi.git/commit/?h=4.5/scsi-fixes&id=d0eb20a863ba7dc1d3f4b841639671f134560be2

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Re: scsi_debug, iosize optimal < minimum (was: test sfdisk, optimal_iosize)

2016-01-29 Thread Ruediger Meier 
Hi,

I've noticed a possible problem with scsi_debug devices where
optimal_io_size < minimum_io_size.

The problem seems reproducable with kernel 4.4.0 and also with
stable version 4.1.15. For stable tree the last known working
version is 4.1.13.

How to reproduce:

uname -mr
modprobe -r scsi_debug 
modprobe scsi_debug dev_size_mb=100 sector_size=512
udevadm settle
devname=$(grep --with-filename scsi_debug /sys/block/*/device/model | awk -F 
'/' '{print $4}')
cat /sys/block/$devname/queue/{minimum_io_size,optimal_io_size}
modprobe -r scsi_debug


## output kernel 4.1.13 (openSUSE Leap):
4.1.13-5-default x86_64
512
32768


## output kernel 4.1.15 (openSUSE Leap):
4.1.15-8-default x86_64
512
64

cu,
Rudi
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