On Sat, 2005-08-06 at 02:10 +0900, Tejun Heo wrote: > Yes, we can do that, but I'm not sure if that would be necessary. > AFAIK, queues are normally not very deep and a tag only occupies one > pointer and one bit. Also, the shrinking operation isn't very common, > at least for traditional SPI devices and SATA drives, I think. > > Are newer SCSI devices (say, SAS/iSCSI) different? - like having very > deep queue and needing dynamic queue depth adjustment? If that's the > case, I think I can implement shrinking in a separate patch. (and try > not to screw up this time ;-) Well, yes, there are reasons for wanting deeper queues, but I'd leave it for the time being. What I'm looking into is support for aic7xxx/aic79xx queueing. There, the sequencer has to have a globally unique tag (from which it generates the device locally unique tag internally). That gives TCQ depths of up to 512 I believe. However, still probably not a significant waste of memory to worry about. James - : send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
