[Xenomai-core] bad/slow TSC hw detected by 2.6.17-rc1-mm1

[Xenomai-core] bad/slow TSC hw detected by 2.6.17-rc1-mm1

[Jim Cromie]

FYI,

Ive just built 17-rc1-mm1, and noted that the new time-keeping-system
http://lwn.net/Articles/176837/

can now detect the buggy TSC on my GEODE-sc1100 cpu,
and also that its apparently fixable by adding 'idle=poll' to 
kernel-boot-line.

Apr  7 11:42:01 truck kernel: [   19.160016] Kernel command line: 
console=ttyS0,115200n81 root=/dev/nfs 
nfsroot=192.168.42.1:/nfshost/truck 
nfsaddrs=192.168.42.100:192.168.42.1:192.168.42.1:255.255.255.0:soekris:eth0 
panic=5 initrd=initrd-2.6.17-rc1-mm1-sk.img  
BOOT_IMAGE=vmlinuz-2.6.17-rc1-mm1-sk
Apr  7 11:42:01 truck kernel: [   24.314851] Time: tsc clocksource has 
been installed.
Apr  7 11:42:01 truck kernel: [   29.977802] TSC appears to be running 
slowly. Marking it as unstable
Apr  7 11:42:01 truck kernel: [   20.460000] Time: pit clocksource has 
been installed.

Apr  7 12:35:56 truck kernel: [   21.562573] Kernel command line: 
console=ttyS0,115200n81 root=/dev/nfs 
nfsroot=192.168.42.1:/nfshost/truck 
nfsaddrs=192.168.42.100:192.168.42.1:192.168.42.1:255.255.255.0:soekris:eth0 
panic=5 initrd=initrd-2.6.17-rc1-mm1-sk.img idle=poll 
BOOT_IMAGE=vmlinuz-2.6.17-rc1-mm1-sk
Apr  7 12:35:56 truck kernel: [   21.563049] using polling idle threads.
Apr  7 12:35:56 truck kernel: [   28.393469] Time: tsc clocksource has 
been installed.


hope this is useful,
jimc

Re: [Xenomai-core] bad/slow TSC hw detected by 2.6.17-rc1-mm1

[Jan Kiszka]

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Jim Cromie wrote:
> FYI,
> 
> Ive just built 17-rc1-mm1, and noted that the new time-keeping-system
> http://lwn.net/Articles/176837/
> 
> can now detect the buggy TSC on my GEODE-sc1100 cpu,
> and also that its apparently fixable by adding 'idle=poll' to
> kernel-boot-line.

Keeps your CPU safe and warm, I guess. ;)

> 
> Apr  7 11:42:01 truck kernel: [   19.160016] Kernel command line:
> console=ttyS0,115200n81 root=/dev/nfs
> nfsroot=192.168.42.1:/nfshost/truck
> nfsaddrs=192.168.42.100:192.168.42.1:192.168.42.1:255.255.255.0:soekris:eth0
> panic=5 initrd=initrd-2.6.17-rc1-mm1-sk.img 
> BOOT_IMAGE=vmlinuz-2.6.17-rc1-mm1-sk
> Apr  7 11:42:01 truck kernel: [   24.314851] Time: tsc clocksource has
> been installed.
> Apr  7 11:42:01 truck kernel: [   29.977802] TSC appears to be running
> slowly. Marking it as unstable
> Apr  7 11:42:01 truck kernel: [   20.460000] Time: pit clocksource has
> been installed.
> 
> Apr  7 12:35:56 truck kernel: [   21.562573] Kernel command line:
> console=ttyS0,115200n81 root=/dev/nfs
> nfsroot=192.168.42.1:/nfshost/truck
> nfsaddrs=192.168.42.100:192.168.42.1:192.168.42.1:255.255.255.0:soekris:eth0
> panic=5 initrd=initrd-2.6.17-rc1-mm1-sk.img idle=poll
> BOOT_IMAGE=vmlinuz-2.6.17-rc1-mm1-sk
> Apr  7 12:35:56 truck kernel: [   21.563049] using polling idle threads.
> Apr  7 12:35:56 truck kernel: [   28.393469] Time: tsc clocksource has
> been installed.
> 
> 
> hope this is useful,
> jimc
> 

Jan


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Re: [Xenomai-core] bad/slow TSC hw detected by 2.6.17-rc1-mm1

[Jim Cromie]

Jan Kiszka wrote:
> Jim Cromie wrote:
>   
>> FYI,
>>
>> Ive just built 17-rc1-mm1, and noted that the new time-keeping-system
>> http://lwn.net/Articles/176837/
>>
>> can now detect the buggy TSC on my GEODE-sc1100 cpu,
>> and also that its apparently fixable by adding 'idle=poll' to
>> kernel-boot-line.
>>     
>
> Keeps your CPU safe and warm, I guess. ;)
>
>   
for me personally, its the new-found certainty that the bug is 
repeatedly observable and correctable :-)

Ive historically had an issue with  my ntp-server on this box,
which slips badly when running latency tests under certain conditions
(ie, the dd workload is using /dev/hda, a real interrupt source, rather 
than /dev/zero)

FWIW, my 2.6.16-ipipe-122 kernel takes a *long* time to boot,
even while printk numbers look good.

The delays/pauses are in several subsystems, most notably after these 
dmesg lines:

[   30.768098] Uniform Multi-Platform E-IDE driver Revision: 7.00alpha2
[   30.775141] ide: Assuming 33MHz system bus speed for PIO modes; 
override with idebus=xx

(1 min pause)

[   31.209246] hda: SanDisk SDCFB-512, CFA DISK drive

[   30.561093] Serial: 8250/16550 driver $Revision: 1.90 $ 4 ports, IRQ 
sharing disabled

30.574876] serial8250: ttyS0 at I/O 0x3f8 (irq = 4) is a 16550A
[   30.586719] serial8250: ttyS1 at I/O 0x2f8 (irq = 3) is a 16550A

(more delays, in various spots, and Im now much more aware of them..)

FWIW, before now, Ive never needed idle=poll, so it seems that 
adeos/xenomai
is more sensitive to these long delays than vanilla linux,  (same for more
recent versions of kernel & adeos).  OTOH, Ive only recently added 
timestamps to
printks, and Im also a bit more sensitive now than I once was ..


Does it make any sense that adeos / xenomai is more sensitive to a bad TSC
than it used to be ?

thanks
jimc