On Fri, 2011-10-28 at 11:37 +0800, Jeff Garzik wrote: > On 10/27/2011 11:21 PM, Lin Ming wrote: > > @@ -3208,6 +3209,11 @@ int ata_scsi_queuecmd(struct Scsi_Host *shost, struct scsi_cmnd *cmd) > > > > ap = ata_shost_to_port(shost); > > > > + if (pm_runtime_suspended(&ap->tdev)) > > + pm_runtime_resume(&ap->tdev); > > + pm_runtime_mark_last_busy(&ap->tdev); > > + pm_request_autosuspend(&ap->tdev); > > + > > spin_lock_irqsave(ap->lock, irq_flags); > > > > > Putting this into the core command dispatch fast-path is rather > disappointing. That's at least one additional lock, plus some atomic > instructions and tests. Maybe move suspend request to the resume function, as below. static int ata_port_runtime_resume(struct device *dev) { struct ata_port *ap = to_ata_port(dev); int rc; rc = ata_port_request_pm(ap, PMSG_ON, ATA_EH_RESET, ATA_EHI_NO_AUTOPSY | ATA_EHI_QUIET, 1); pm_runtime_mark_last_busy(dev); pm_request_autosuspend(dev); return rc; } Then the fast-path looks like, @@ -3208,6 +3209,9 @@ int ata_scsi_queuecmd(struct Scsi_Host *shost, struct scsi_cmnd *cmd) ap = ata_shost_to_port(shost); + if (pm_runtime_suspended(&ap->tdev)) + pm_runtime_resume(&ap->tdev); + spin_lock_irqsave(ap->lock, irq_flags); ata_scsi_dump_cdb(ap, cmd); What do you think? Thanks, Lin Ming -- To unsubscribe from this list: send the line "unsubscribe linux-ide" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html