Power Management References - deep

• Power Management References - deep
  • Notes
    • Suspension logs
    • Resume logs
  • References
    • Evolution of Suspend-to-Idle Support in The Linux Kernel - Rafael Wysocki (LCA 2021 Online)

Notes

Sometimes "suspend-to-ram" refers to this. This is what happens if:

1. The /sys/power/mem_sleep is set to deep; and
2. mem is written to /sys/power/state.

Suspension logs

Suspend-to-ram in general requires platform support. One notable behavior is that the non-booting processor or taken offline.

[  147.319976] PM: suspend entry (deep)
[  147.355021] Filesystems sync: 0.035 seconds
[  147.359142] Freezing user space processes
[  147.361191] Freezing user space processes completed (elapsed 0.002 seconds)
[  147.361196] OOM killer disabled.
[  147.361197] Freezing remaining freezable tasks
[  147.362351] Freezing remaining freezable tasks completed (elapsed 0.001 seconds)
[  147.362392] printk: Suspending console(s) (use no_console_suspend to debug)
[  147.476298] sd 0:0:0:0: [sda] Synchronizing SCSI cache
[  147.502014] ata1.00: Entering standby power mode
[  147.716431] PM: suspend of devices complete after 353.883 msecs
[  147.716448] PM: start suspend of devices complete after 354.152 msecs
[  147.728258] PM: late suspend of devices complete after 11.811 msecs
[  147.728574] ACPI: EC: interrupt blocked
[  147.812310] PM: noirq suspend of devices complete after 84.008 msecs
[  147.812314] ACPI: PM: Preparing to enter system sleep state S3
[  147.920421] ACPI: EC: event blocked
[  147.920422] ACPI: EC: EC stopped
[  147.920423] ACPI: PM: Saving platform NVS memory
[  147.920443] Disabling non-boot CPUs ...
[  147.921744] smpboot: CPU 1 is now offline
[  147.923644] smpboot: CPU 2 is now offline
[  147.925155] smpboot: CPU 3 is now offline
[  147.925397] Checking wakeup interrupts
[  147.925400] Calling kvm_suspend+0x0/0x40 [kvm]
[  147.925458] Calling mce_syscore_suspend+0x0/0x20
[  147.925461] Calling ledtrig_cpu_syscore_suspend+0x0/0x20
[  147.925465] Calling timekeeping_suspend+0x0/0x310
[  147.925502] Calling irq_gc_suspend+0x0/0x80
[  147.925504] Calling save_ioapic_entries+0x0/0x170
[  147.925625] Calling i8259A_suspend+0x0/0x40
[  147.925629] Calling fw_suspend+0x0/0x20
[  147.925631] Calling acpi_save_bm_rld+0x0/0x30
[  147.925636] Calling intel_epb_save+0x0/0x40
[  147.925639] Calling lapic_suspend+0x0/0x30

Resume logs

The resume process pretty much unwind what suspension has done.

[  147.926320] ACPI: PM: Low-level resume complete
[  147.926352] ACPI: EC: EC started
[  147.926353] ACPI: PM: Restoring platform NVS memory
[  147.926359] Calling init_counter_refs+0x0/0x60
[  147.926367] Calling lapic_resume+0x0/0x30
[  147.926390] Calling intel_epb_restore+0x0/0xb0
[  147.926395] Calling acpi_restore_bm_rld+0x0/0x70
[  147.926401] Calling irqrouter_resume+0x0/0x60
[  147.926407] Calling i8259A_resume+0x0/0x40
[  147.926544] Calling i8237A_resume+0x0/0xc0
[  147.926622] Calling ioapic_resume+0x0/0x150
[  147.926677] Calling irq_gc_resume+0x0/0x80
[  147.926682] Calling irq_pm_syscore_resume+0x0/0x20
[  147.926750] Calling timekeeping_resume+0x0/0x1b0
[  147.926790] Timekeeping suspended for 3.123 seconds
[  147.926807] Calling ledtrig_cpu_syscore_resume+0x0/0x20
[  147.926815] Calling mce_syscore_resume+0x0/0x30
[  147.926833] Calling microcode_bsp_resume+0x0/0x50
[  147.926839] Calling kvm_resume+0x0/0x70 [kvm]
[  147.926999] Enabling non-boot CPUs ...
[  147.927041] smpboot: Booting Node 0 Processor 1 APIC 0x2
[  147.966947] CPU1 is up
[  147.967290] smpboot: Booting Node 0 Processor 2 APIC 0x1
[  147.968447] CPU2 is up
[  147.968467] smpboot: Booting Node 0 Processor 3 APIC 0x3
[  148.001286] CPU3 is up
[  148.004216] ACPI: PM: Waking up from system sleep state S3
[  148.006020] ACPI: EC: interrupt unblocked
[  149.117600] PM: noirq resume of devices complete after 1112.019 msecs
[  149.117911] PM: early resume of devices complete after 0.250 msecs
[  149.117985] ACPI: EC: event unblocked
[  149.253240] PM: resume of devices complete after 135.351 msecs
[  149.254129] OOM killer enabled.
[  149.254136] Restarting tasks ... done.
[  149.262149] random: crng reseeded on system resumption
[  149.364034] PM: suspend exit

References

Evolution of Suspend-to-Idle Support in The Linux Kernel - Rafael Wysocki (LCA 2021 Online)