On 4/30/20 4:15 PM, John Garry wrote:
On 30/04/2020 14:18, Hannes Reinecke wrote:
From: Hannes Reinecke <hare@xxxxxxxx>
Quite a lot of drivers are using management commands internally, which
typically use the same hardware tag pool (ie they are being allocated
from the same hardware resources) as the 'normal' I/O commands.
These commands are set aside before allocating the block-mq tag bitmap,
so they'll never show up as busy in the tag map.
The block-layer, OTOH, already has 'reserved_tags' to handle precisely
this situation.
So this patch adds a new field 'nr_reserved_cmds' to the SCSI host
template to instruct the block layer to set aside a tag space for these
management commands by using reserved_tags.
Signed-off-by: Hannes Reinecke <hare@xxxxxxxx>
It may be worth adding this field to scsi_host_template. And we should
also prob mention this in Documentation/scsi/scsi_mid_low_api.txt
Right, indeed, will be doing so.
Haven't done it as long as this is still an RFC; guess when we'll get
the SAS bits sorted (hint, hint :-) and no further objections are coming
wrt the overall design I'll be sending out a 'real' patchset with the
documentation bits sorted, too.
Apart from that, thanks:
Reviewed-by: John Garry <john.garry@xxxxxxxxxx>
Thanks for the review!
Cheers,
Hannes
--
Dr. Hannes Reinecke Teamlead Storage & Networking
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