This patch reduces S3 resume time from 10+ seconds to less than a second on systems with SATA drives. It does this by making ata port and scsi disk resume non-blocking. This is v4, sent in response to Tejun Huo's comments and with some small fixes made after testing. OVERVIEW The essential issue behind hard disks' lengthy resume time is the ata port driver blocking until the ATA port hardware is finished coming online. So the kernel isn't really doing anything during all those seconds that the disks are resuming, it's just blocking until the hardware says it's ready to accept commands. Applying this patch set allows SATA disks to resume asynchronously without holding up system resume, thus allowing the UI to come online much more quickly. There may be a short period after resume where the disks are still spinning up in the background, but it will only momentarily affect applications using that disk. The patch set has two parts which apply to ata_port_resume and sd_resume respectively. Both are required to achieve any real performance benefit, but they will still function independantly without a performance hit. PERFORMANCE DATA [Computer One Test - 10.5X speedup on S3 resume] Platform: Ubuntu Raring Ringtail (13.04) kernel 3.11.0-rc7 Cpu: Intel(R) Core(TM) i7-3960X CPU @ 3.30GHz Ahci: Intel C600/X79 series chipset 6-Port SATA AHCI (r5) Disk config (using all 6 ahci ports): 240 GB SSD, 3 TB HD, 500 GB HD, DVD-ROM (with cd inserted), 2 TB HD, 1 TB HD Resume time: [unpatched 11656ms] [patched 1110ms] [Computer Two Test - 12X speedup on S3 resume] Platform: Ubuntu Raring Ringtail (13.04) kernel 3.11.0-rc7 Cpu: Intel(R) Core(TM) i7-3770 CPU @ 3.40GHz Ahci: Intel 7 Series/C210 Series Chipset Family 6-port SATA [AHCI mode] (r4) Disk config (using 1 ahci port): 320 GB Hard Disk Resume time: [unpatched 5416 ms] [patched 448 ms] [Computer Three Test - 7.8X speedup on S3 resume] Platform: Ubuntu Raring Ringtail (13.04) kernel 3.11.0-rc7 Cpu: Intel(R) Core(TM) i7-4770S CPU @ 3.10GHz Ahci: Intel Lynx Point 6-port SATA Controller 1 [AHCI mode] (r2) Disk config (using 2 ahci ports): DVD-ROM (empty), 500 GB Hard Disk Resume time: [unpatched 5385ms] [patched 688ms] CHANGELOG v4: Jan 15, 2014 [in response to Tejun Huo] - completely removed the pm_result member of the ata_port struct - result from ata_port_suspend/resume is now returned from the function instead of into a pointer location - ata_port_request_pm now only returns 0/-EAGAIN for pass/fail [fixes] - moved the scsi_disk_put call from sd_resume_complete into sd_resume since it needs to be called from the same context v3: Jan 14, 2014 [in response to Tejun Huo] - respun the ata patch to merge the entire code path into async resume i.e. resume, restore, and thaw. - re-tested the changes in hibernate to verify there are no issues - respun the sd patch to apply clean over 3.13 rc8, no other changes v2: Oct 17, 2013 [in response to Oliver Neukum] - Added scsi cmd error reporting through the scsi_sense_hdr [in response to James Bottomley] - unified the sd_resume code path by just making sd_resume async. Thus all three resume callbacks: resume, restore, and runtime-resume will use it, but there is a performance benefit for resume only. [in response to Bartlomiej Zolnierkiewicz] - unified the __ata_port_resume_common code path to include an async parameter. This way there's no need to re-implement ata_port_request_pm. v1: Sept 6, 2013 -- 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
