It is not everyday that a kernel operation gets 2x faster. Nice find by Todd and his AnalyzeSuspend tool [1].
Todd is on vacation so I am taking care of these patches to make sure they get in the queue for 3.15. The significant changes from Todd's last submission [2]: 1/ Split out the pure cleanup into its own patch, and expand it to clean up libsas as well 2/ Move the entirety of scsi_device resume to an async context. As written, v4 of the patchset overlapped the scsi-start-stop command with the scsi_device_resume(). Now in v5 the queue restart is properly ordered with the completion of the scsi-start-stop command. Resume completion time as reported by: "echo devices > /sys/power/pm_test && echo mem > /sys/power/state" BEFORE: PM: resume of devices complete after 2271.097 msecs AFTER: PM: resume of devices complete after 1057.404 msecs On a system with two SSDs attached via AHCI. -- Dan [1]: Todd's testing showing up to 12x resume latency improvement in some cases: https://01.org/suspendresume/blogs/tebrandt/2013/hard-disk-resume-optimization-simpler-approach [2]: Todd's v4 patchset: [PATCH v4 0/2] http://marc.info/?l=linux-ide&m=138984698103487&w=2 [PATCH v4 1/2] http://marc.info/?l=linux-ide&m=138984713203515&w=2 [PATCH v4 2/2] http://marc.info/?l=linux-ide&m=138984722003539&w=2 --- Dan Williams (2): libata, libsas: kill pm_result and related cleanup scsi: async sd resume Todd Brandt (1): libata: async resume drivers/ata/libata-core.c | 75 ++++++++++----------------- drivers/ata/libata-eh.c | 13 +---- drivers/scsi/libsas/sas_ata.c | 35 ++---------- drivers/scsi/scsi.c | 3 + drivers/scsi/scsi_pm.c | 115 ++++++++++++++++++++++++++++++++--------- drivers/scsi/scsi_priv.h | 1 drivers/scsi/sd.c | 1 include/linux/libata.h | 9 +-- include/scsi/libsas.h | 1 9 files changed, 134 insertions(+), 119 deletions(-) -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html
