Linux Archive

Linux Archive (
-   Device-mapper Development (
-   -   dm_calculate_queue_limits and default values (

07-29-2011 02:20 PM

dm_calculate_queue_limits and default values

I'm a newbie on dm and all this stuff,
but I'm wondering why "max_segments" of all dm's queue is always
128 (cat /sys/block/dm-*/queue/max_segments), even if all devices used
in the dm have another value (cat /sys/devices/pci0000:00/0000:00:1f.2/host0/scsi_host/host0/sg_tablesize
: 168).

I looked over the source code of dm_calculate_queue_limits,
and saw that limits of all devices are combined with default limits (blk_set_default_limits(limits);).
But, the value used is always the min_not_zero, so always 128, the default

As I understand, even if all devices
have big limits, default values will be used.

Is my understanding wrong or there is
a bug ?

Thank you to explain me the dm operation.


Benoit Welterlen--
dm-devel mailing list

All times are GMT. The time now is 12:20 PM.

VBulletin, Copyright ©2000 - 2014, Jelsoft Enterprises Ltd.
Content Relevant URLs by vBSEO ©2007, Crawlability, Inc.