Re: [PATCH -next] blk-mq: fix boot time regression for scsi drives with multiple hctx

[Christoph Hellwig]

On Tue, Jun 14, 2022 at 09:15:36PM +0800, Yu Kuai wrote:
> > for making so long, so I guess there must be other delay added by the feature
> > of BLK_MQ_F_TAG_HCTX_SHARED.
> 
> Please see details in the reasons 2), scsi scan will call
> __scsi_remove_device() a lot of times(each host, each channel, each
> target).

Well, if the SCSI core does that you are falling back to a sequentical
scan instad of using REPORT LUNS.  Which seems like a bug on its own
that is worth investigation.