On Sat, Mar 23 2013, Aaron Lu wrote: > In August 2010, Jens and Alan discussed about "Runtime PM and the block > layer". http://marc.info/?t=128259108400001&r=1&w=2 > And then Alan has given a detailed implementation guide: > http://marc.info/?l=linux-scsi&m=133727953625963&w=2 > > To test: > # ls -l /sys/block/sda > /sys/devices/pci0000:00/0000:00:1f.2/ata1/host0/target0:0:0/0:0:0:0/block/sda > > # echo 10000 > /sys/devices/pci0000:00/0000:00:1f.2/ata1/host0/target0:0:0/0:0:0:0/power/autosuspend_delay_ms > # echo auto > /sys/devices/pci0000:00/0000:00:1f.2/ata1/host0/target0:0:0/0:0:0:0/power/control > Then you'll see sda is suspended after 10secs idle. > > [ 1767.680192] sd 2:0:0:0: [sda] Synchronizing SCSI cache > [ 1767.680317] sd 2:0:0:0: [sda] Stopping disk > > And if you do some IO, it will resume immediately. > [ 1791.052438] sd 2:0:0:0: [sda] Starting disk > > For test, I often set the autosuspend time to 1 second. If you are using > a GUI, the 10 seconds delay may be too long that the disk can not enter > runtime suspended state. > > Note that sd's runtime suspend callback will dump some kernel messages > and the syslog daemon will write kernel message to /var/log/messages, > making the disk instantly resume after suspended. So for test, the > syslog daemon should better be temporarily stopped. > > A git repo for it, on top of block/for-next: > https://github.com/aaronlu/linux.git blockpm > > v12: > - Split patch 1 into 2 patches, one introduces REQ_PM in block layer > and one uses that flag in SCSI layer, suggested by Jens Axboe. Thanks Aaron, I've applied 1, and 3-4. I'll leave 2 and 5 for James to pickup. James, if you want me to carry them, just let me know. -- Jens Axboe -- To unsubscribe from this list: 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
