On Thursday, October 07, 2010, Sameer Nanda wrote: > (resending as plain text, sorry if you got dupe messages) > > On Wed, Oct 6, 2010 at 7:19 PM, Greg KH <gregkh@xxxxxxx> wrote: > > On Wed, Oct 06, 2010 at 04:15:19PM -0700, Sameer Nanda wrote: > >> Read the TSC upon resuming and print it out. This is useful > >> in helping figure out amount of time spent in the BIOS when > >> resuming from suspend. > >> > >> Change-Id: I1d6a32bd62421becddecd152d561763e5f3e1101 > > > > What is this tag for? I don't think it matches anything the kernel > > community wants, do you? > > Yeah, its not needed. Let me resubmit the patch without this tag. > > > > > And are you always going to be printing this out? Why do we want to > > know this every time? > > Yes, every time. This helps track variance in BIOS resume times > within a single boot. > > > > >> Signed-off-by: Sameer Nanda <snanda@xxxxxxxxxxxx> > >> --- > >> drivers/acpi/sleep.c | 4 ++++ > >> 1 files changed, 4 insertions(+), 0 deletions(-) > >> > >> diff --git a/drivers/acpi/sleep.c b/drivers/acpi/sleep.c > >> index c0fed2e..f0588fa 100644 > >> --- a/drivers/acpi/sleep.c > >> +++ b/drivers/acpi/sleep.c > >> @@ -214,6 +214,7 @@ static int acpi_suspend_enter(suspend_state_t pm_state) > >> acpi_status status = AE_OK; > >> unsigned long flags = 0; > >> u32 acpi_state = acpi_target_sleep_state; > >> + u64 tsc; > >> > >> ACPI_FLUSH_CPU_CACHE(); > >> > >> @@ -235,6 +236,9 @@ static int acpi_suspend_enter(suspend_state_t pm_state) > >> > >> case ACPI_STATE_S3: > >> do_suspend_lowlevel(); > >> + rdtscll(tsc); > >> + printk(KERN_INFO "TSC at resume: %llu\n", > >> + (unsigned long long)tsc); > > > > How long does this take, will it slow down resume? > > The impact is ~10us (as measured on an Intel Atom N455 @ 1.66Ghz). > Given that resume time is currently of the order of 1sec, its in the > noise range. Do I think correctly that it assumes the TSC will be updated in the sleep state? Rafael -- To unsubscribe from this list: send the line "unsubscribe linux-acpi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
