Messages in this thread | | | Date | Fri, 25 Feb 2011 15:17:47 -0500 | From | Steven Rostedt <> | Subject | Re: Performance/resume issues on Toshiba NB305 |
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Would be helpful to Cc the people that may help you.
On Fri, Feb 25, 2011 at 10:42:39AM -0600, Seth Forshee wrote: > I've been looking into a couple of problems with this machine that have > me a bit stumped at the moment. The two problems may or may not be > related, so I'm including details about both issues below. If anyone has > any ideas, I'd love to hear them. Note that these are not recent > regressions; they've been around since at least 2.6.32. > > The CPU in this machine is an Atom N450. > > When booted normally the performance on this machine is very poor, but > when booted with any of nohz=off, nolapic, or nohpet it improves > significantly. The performance also improves if I use the patch below to > force the hpet to remain in periodic mode (with hpet=periodic on the > command line). > > One other thing I noticed when I had added some logging related to hpet > rearming is 3-5 second periods of no log activity occurring fairly > frequently, whereas such inactive periods are infrequent when > performance is good and are also infrequent on another machine with very > similar hardware and no performance issues. > > The machine also hangs for 5 minutes during resume, unless booted with > both nohz=off and highres=off, or with hpet=periodic using the patch > below. I've traced this down to hanging in an SMI handler during the > ACPI _WAK method execution. The 5 minutes corresponds to how long it > takes for the low 32 bits of the hpet to wrap in this machine, and since > the options that eliminate the hang result in the hpet being in periodic > mode during _WAK method execution I suspect that the SMI handler is > hanging until a timer interrupt happens. > > One possible explanation here is that the performance problems are also > related to hangs in SMI handlers until there's a timer interrupt, > although I don't know how that explains why some of the command line > options eliminate the performance issues.
Sounds like a buggy BIOS to me. Is there upgrades available for this box?
-- Steve
> > Note also that I've already looked into the triggering for IRQ0, and it > seems to be correct. > > Thanks, > Seth > > > diff --git a/arch/x86/kernel/hpet.c b/arch/x86/kernel/hpet.c > index 4ff5968..ab10012 100644 > --- a/arch/x86/kernel/hpet.c > +++ b/arch/x86/kernel/hpet.c > @@ -87,6 +87,7 @@ static inline void hpet_clear_mapping(void) > static int boot_hpet_disable; > int hpet_force_user; > static int hpet_verbose; > +static int hpet_oneshot_disable; > > static int __init hpet_setup(char *str) > { > @@ -97,6 +98,8 @@ static int __init hpet_setup(char *str) > hpet_force_user = 1; > if (!strncmp("verbose", str, 7)) > hpet_verbose = 1; > + if (!strncmp("periodic", str, 8)) > + hpet_oneshot_disable = 1; > } > return 1; > } > @@ -306,6 +309,10 @@ static void hpet_legacy_clockevent_register(void) > hpet_clockevent.min_delta_ns = clockevent_delta2ns(HPET_MIN_PROG_DELTA, > &hpet_clockevent); > > + /* Disable one-shot mode if requested */ > + if (hpet_oneshot_disable) > + hpet_clockevent.features &= ~CLOCK_EVT_FEAT_ONESHOT; > + > /* > * Start hpet with the boot cpu mask and make it > * global after the IO_APIC has been initialized. > diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c > index 48b2761..8e84c11 100644 > --- a/kernel/time/tick-broadcast.c > +++ b/kernel/time/tick-broadcast.c > @@ -565,10 +565,15 @@ void tick_broadcast_switch_to_oneshot(void) > > raw_spin_lock_irqsave(&tick_broadcast_lock, flags); > > - tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT; > bc = tick_broadcast_device.evtdev; > + if (bc && !(bc->features & CLOCK_EVT_FEAT_ONESHOT)) > + goto unlock; > + > + tick_broadcast_device.mode = TICKDEV_MODE_ONESHOT; > if (bc) > tick_broadcast_setup_oneshot(bc); > + > +unlock: > raw_spin_unlock_irqrestore(&tick_broadcast_lock, flags); > } >
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