2007-01-28 05:35:51

by Sunil Naidu

[permalink] [raw]
Subject: 2.6.20-rc6-rt2 - SMP/x86 -- questions about .config selection

Hi Ingo,

I did boot with (almost) no problems. Here is ps ax info:-

PID TTY STAT TIME COMMAND
1 ? Ss 0:00 init [5]
2 ? S 0:00 [migration/0]
3 ? S 0:00 [posix_cpu_timer]
4 ? S 0:00 [softirq-high/0]
5 ? S 0:00 [softirq-timer/0]
6 ? S 0:00 [softirq-net-tx/]
7 ? S 0:00 [softirq-net-rx/]
8 ? S 0:00 [softirq-block/0]
9 ? S 0:00 [softirq-tasklet]
10 ? S 0:00 [softirq-sched/0]
11 ? S 0:00 [softirq-hrtimer]
12 ? S 0:00 [softirq-rcu/0]
13 ? S< 0:00 [desched/0]
14 ? S 0:00 [migration/1]
15 ? S 0:00 [posix_cpu_timer]
16 ? S 0:00 [softirq-high/1]
17 ? S 0:00 [softirq-timer/1]
18 ? S 0:00 [softirq-net-tx/]
19 ? S 0:00 [softirq-net-rx/]
20 ? S 0:00 [softirq-block/1]
21 ? S 0:00 [softirq-tasklet]
22 ? S 0:00 [softirq-sched/1]
23 ? S 0:00 [softirq-hrtimer]
24 ? S 0:00 [softirq-rcu/1]
.........
.........

Here is the interrupt info:-

CPU0 CPU1
0: 354 0 IO-APIC-edge timer
1: 361 0 IO-APIC-edge i8042
8: 1 0 IO-APIC-edge rtc
9: 0 0 IO-APIC-fasteoi acpi
12: 7 0 IO-APIC-edge i8042
14: 1985 0 IO-APIC-edge ide0
16: 13042 0 IO-APIC-fasteoi uhci_hcd:usb4, HDA
Intel, i915@pci:0000:00:02.0
18: 0 0 IO-APIC-fasteoi uhci_hcd:usb3
19: 11520 0 IO-APIC-fasteoi uhci_hcd:usb2, libata
20: 2 0 IO-APIC-fasteoi uhci_hcd:usb1, ehci_hcd:usb5
21: 515 0 IO-APIC-fasteoi eth0
NMI: 0 0
LOC: 23573 24545
ERR: 0
MIS: 0


I did get REMINDER, the following debugging options are turned on in
your .config:

CONFIG_CRITICAL_IRQSOFF_TIMING
CONFIG_FUNCTION_TRACE

This I have understood, no issues here.

There is some confusion for me while configuring a rt kernel &
proceeding for experiments. I did choose the following:-

NO_HZ=y
HIGH_RES_TIMERS=y
SMP=y
PREEMPT_VOLUNTARY=y
PREEMPT_SOFTIRQS=y
PREEMPT_HARDIRQS=y
SPINLOCK_BKL=y
CLASSIC_RCU=y
SCHED_SMT=y
IRQBALANCE=y
HZ_1000=y


#1 Is this correct to say PREEMPT_VOLUNTARY=y for rt on this desktop PC?
#2 I am not clear about IRQ config selection (which one should be
enable/disable for a PC, I did select all as shown in the above
config). Any suggestion?
#3 Any other parameter(s) I need to enable/disable to get better
results? (did disable APM)


Thanks,

~Su37


2007-01-28 09:16:49

by Ingo Molnar

[permalink] [raw]
Subject: Re: 2.6.20-rc6-rt2 - SMP/x86 -- questions about .config selection


* Sunil Naidu <[email protected]> wrote:

> There is some confusion for me while configuring a rt kernel &
> proceeding for experiments. I did choose the following:-
>
> NO_HZ=y
> HIGH_RES_TIMERS=y
> SMP=y
> PREEMPT_VOLUNTARY=y
> PREEMPT_SOFTIRQS=y
> PREEMPT_HARDIRQS=y
> SPINLOCK_BKL=y
> CLASSIC_RCU=y
> SCHED_SMT=y
> IRQBALANCE=y
> HZ_1000=y
>
>
> #1 Is this correct to say PREEMPT_VOLUNTARY=y for rt on this desktop
> #PC?

well, PREEMPT_RT is the best preemption method.

> #2 I am not clear about IRQ config selection (which one should be
> enable/disable for a PC, I did select all as shown in the above
> config). Any suggestion?

it's OK. If you select PREEMPT_RT then all the necessary preemption
options get auto-selected for you.

> #3 Any other parameter(s) I need to enable/disable to get better
> results? (did disable APM)

check out the configs of the -rt yum repository, those are pretty
optimal:

http://people.redhat.com/mingo/realtime-preempt/yum/

Ingo