On 2018-04-06 16:11, Philippe Gerum wrote:
> On 04/06/2018 03:38 PM, Jan Kiszka wrote:
>> On 2018-04-06 08:54, Philippe Gerum wrote:
>>> On 04/05/2018 10:13 PM, Jan Kiszka wrote:
>>>> On 2018-03-27 15:12, Philippe Gerum wrote:
>>>>> On 03/10/2018 11:06 PM, Jan Kiszka wrote:
>>>>>> On 2018-03-09 08:51, Jan Kiszka wrote:
>>>>>>> 4.9 requires more work, I've pushed the beginning to wip/4.9 in the same
>>>>>>> repo.
>>>>>>
>>>>>> I started to patch further on this during my flight (wip/4.9 updated),
>>>>>> noticed that the 4.14-wip queue will need a little bit sysentry tweaking
>>>>>> as well (missing 64-bit syscall dispatching), and then had to find 4.9
>>>>>> in a rather unfortunate state /wrt x86-64: CPUs are no longer idling
>>>>>> properly. I went back to ipipe-core-4.9.24-x86-2, without a difference.
>>>>>>
>>>>>> If you should look into 4.9-x86 as you indicated, please check this.
>>>>>
>>>>> Both issues fixed in 4.9.90/x86 as pushed lately. The result has run
>>>>> overnight in 64bit mode, and for a couple of hours in ia32emu mode. So
>>>>> far so good.
>>>>
>>>> Just trying 4.9.90-x86-6 in KVM, and I'm still finding 100% (virtual)
>>>> CPU load. I also triggered this with stable-3.0.x:
>>>>
>>>> [  237.455846] WARNING: CPU: 0 PID: 1055 at 
>>>> ../kernel/xenomai/posix/timerfd.c:57 timerfd_read+0x2a6/0x350
>>>> [  237.460728] Modules linked in:
>>>> [  237.461490] CPU: 0 PID: 1055 Comm: sampling-1052 Not tainted 4.9.90+ #11
>>>> [  237.461490] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 
>>>> rel-1.11.1-0-g0551a4be2c-prebuilt.qemu-project.org 04/01/2014
>>>> [  237.461490] I-pipe domain: Xenomai
>>>> [  237.461490]  ffffc90001b7fdb0 ffffffff8145e395 0000000000000000 
>>>> 0000000000000000
>>>> [  237.461490]  ffffc90001b7fdf0 ffffffff810e7261 000000393d61d170 
>>>> ffffc900003e6008
>>>> [  237.461490]  0000000000000003 0000000000000008 00007f513e8c2de8 
>>>> 0000000000026200
>>>> [  237.461490] Call Trace:
>>>> [  237.461490]  [<ffffffff8145e395>] dump_stack+0xb2/0xdd
>>>> [  237.461490]  [<ffffffff810e7261>] __warn+0xd1/0xf0
>>>> [  237.461490]  [<ffffffff810e734d>] warn_slowpath_null+0x1d/0x20
>>>> [  237.461490]  [<ffffffff812423b6>] timerfd_read+0x2a6/0x350
>>>> [  237.461490]  [<ffffffff812174ec>] rtdm_fd_read+0x13c/0x3b0
>>>> [  237.461490]  [<ffffffff81220260>] ? CoBaLt_ioctl+0x20/0x20
>>>> [  237.461490]  [<ffffffff8122026e>] CoBaLt_read+0xe/0x10
>>>> [  237.461490]  [<ffffffff81235894>] handle_head_syscall+0x184/0x4b0
>>>> [  237.461490]  [<ffffffff81236288>] ipipe_fastcall_hook+0x18/0x20
>>>> [  237.461490]  [<ffffffff811a9054>] ipipe_handle_syscall+0x64/0x110
>>>> [  237.461490]  [<ffffffff81002b33>] do_syscall_64+0x43/0x1c0
>>>> [  237.461490]  [<ffffffff81840b43>] 
>>>> entry_SYSCALL_64_after_swapgs+0x5d/0xdb
>>>> [  237.461490] ---[ end trace 9d2476a38b0c5379 ]---
>>>>
>>>> I will debug this tomorrow.
>>>>
>>>
>>> I can't reproduce this, the loadavg on my qemu instance consistently
>>> converges to 0.0x figures while running the latency test (10Khz or 1Khz,
>>> same). I'm now running 4.9.92, but I don't think this should make any
>>> difference, since I could trace the box entering the idle state on .90.
>>>
>>> Are you running the ia32emu mode, or x86_64? Also, could you share your
>>> .config for building the guest kernel?
>>
>> Config is the same I sent back then. Userland is 64-bit, compat support
>> enabled.
> 
> You only sent me the CONFIG_IDLE* settings I asked for. I'd need the
> whole file now.

Sorry, though I did. Attached.

> 
>>
>> The reason I see so far: xnclock_core_local_shot never sets XNIDLE.
> 
> It does here (I traced it). However this should depend on the NO_HZ
> settings, mine are :
> 
> CONFIG_TICK_ONESHOT=y
> CONFIG_NO_HZ_COMMON=y
> # CONFIG_HZ_PERIODIC is not set
> CONFIG_NO_HZ_IDLE=y
> CONFIG_NO_HZ=y
> 

Same here.

>> I
>> suspect we always have a timer registered, that for the host clock. So
> 
> In that case, the timer is not idle Xenomai-wise.
> 
>> we can't become idle this way. I'm not even sure that this test makes
>> sense because a pending RT timer does not make a non-idle system.
>>
> 
> This is not about testing for Cobalt idleness, but for its core timer
> idleness, given that the core timer is shared between both kernels. We
> want to know whether we may allow the regular kernel to shutdown the
> clock event hardware for entering a sleep state. XNIDLE -> XNTIMERIDLE
> if you will. I covered this stuff in Documentation/ipipe.rst lately.
> 

I still don't see the problem. We own the timer, Linux does not program
it. And letting Linux call hlt does not disturb the timer programming,
in most cases at least (there might be some weird old broken hardware).

Jan
-------------- next part --------------
A non-text attachment was scrubbed...
Name: .config.xz
Type: application/x-xz
Size: 21268 bytes
Desc: not available
URL: 
<http://xenomai.org/pipermail/xenomai/attachments/20180406/32e24aae/attachment.bin>
_______________________________________________
Xenomai mailing list
Xenomai@xenomai.org
https://xenomai.org/mailman/listinfo/xenomai

Reply via email to