On 9/2/19 10:47 AM, John Garry wrote: > On 26/08/2019 16:27, Hannes Reinecke wrote: >> On 8/23/19 3:26 PM, John Garry wrote: >>> On 29/05/2019 14:28, Hannes Reinecke wrote: >>>> Hi all, >>>> >>>> quite some drivers use internal commands for various purposes, most >>>> commonly sending TMFs or querying the HBA status. >>>> While these commands use the same submission mechanism than normal >>>> I/O commands, they will not be counted as outstanding commands, >>>> requiring those drivers to implement their own mechanism to figure >>>> out outstanding commands. >>>> This patchset enables the use of reserved tags for the SCSI midlayer, >>>> enabling LLDDs to rely on the block layer for tracking outstanding >>>> commands. >>>> More importantly, it allows LLDD to request a valid tag from the block >>>> layer without having to implement some tracking mechanism within the >>>> driver. This removes quite some hacks which were required for some >>>> drivers (eg. fnic or snic). >>>> >>>> As usual, comments and reviews are welcome. >>>> >>> >>> Hi Hannes, >>> >>> I was wondering if you have any plans to progress this series? >>> >>> I don't mind helping out... >>> >> Thanks for the reminder. > > Hi Hannes, > >> I'll need to re-evaluate this where we stand now with shared tags; > > As Ming Lei mentioned in > https://www.spinics.net/lists/linux-block/msg43779.html, the future for > hostwide shared tags doesn't look bright. I would tend to agree. > >> this patchset partially relies on them. > > In which way? I didn't think/hope it did. > >> Will be sending an updated patchset. > > For me, the way I see forward is to upstream this series, in addition to > Ming's, linked above. > > As for LLDDs and the unique tag problem, I suggest that they use sbitmap > to generate the tag internally if they want to expose multiple queues. > From our testing, using managed interrupts + sbitmap still far > outperforms non-managed interrupts. > > This approach would mean that we can still revisit hostwide shared tags > or other some other approach in future. > Hmm. True. Will be checking. Cheers, Hannes -- Dr. Hannes Reinecke Teamlead Storage & Networking hare@xxxxxxx +49 911 74053 688 SUSE Software Solutions Germany GmbH, Maxfeldstr. 5, 90409 Nürnberg HRB 247165 (AG München), GF: Felix Imendörffer
