Re: [Xenomai-core] Troubles with switchtest
Jan Kiszka wrote: > Gilles Chanteperdrix wrote: >> Jan Kiszka wrote: >>> I think the trick against /this/ is preempt_disable/enable in >>> kernel_fpu/begin/end. But that won't work for Xenomai, of course. >> Well, that does not prevent an IRQ or a page fault from computing a RAID >> cheksum... > > If this is allowed, then... My impression was that FPU access is not > legal from IRQ context. If you have a mapped file on a raid disk and a page fault triggers a write, I think the RAID routines will be used. But you are right, maybe there is a test to use the plain integer RAID routines when called from interrupt context. -- Gilles. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> I think the trick against /this/ is preempt_disable/enable in >> kernel_fpu/begin/end. But that won't work for Xenomai, of course. > > Well, that does not prevent an IRQ or a page fault from computing a RAID > cheksum... If this is allowed, then... My impression was that FPU access is not legal from IRQ context. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
Jan Kiszka wrote: > I think the trick against /this/ is preempt_disable/enable in > kernel_fpu/begin/end. But that won't work for Xenomai, of course. Well, that does not prevent an IRQ or a page fault from computing a RAID cheksum... -- Gilles. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> Gilles Chanteperdrix wrote: >>> Jan Kiszka wrote: Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> Hi Gilles, >> >> I'm currently facing a nasty effect with switchtest over latest git head >> (only tested this so far): running it inside my test VM (ie. with >> frequent excessive latencies) I get a stalled Linux timer IRQ quite >> quickly. System is otherwise still responsive, Xenomai timers are still >> being delivered, other Linux IRQs too. switchtest complained about >> >> "Warning: Linux is compiled to use FPU in kernel-space." >> >> when it was started. Kernels are 2.6.28.9/ipipe-x86-2.2-07 and >> 2.6.29.3/ipipe-x86-2.3-01 (LTTng patched in, but unused), both show the >> same effect. >> >> Seen this before? > The warning about Linux being compiled to use FPU in kernel-space means > that you enabled soft RAID or compiled for K7, Geode, or any other RAID is on (ordinary server config). >>> By the way, I wonder how MMX accelerated software raid works on K7, >>> since the way I understand the code, calls to kernel_fpu_begin() can not >>> be nested. >>> >>> If you think they can be nested, then we can make switchtest test fpu in >>> Linux kernel-space when these options are enabled. >> Sorry, I haven't looked that close into the in-kernel FPU handling so >> far. What users are nested in the standard kernel? Or is it RAID in itself? > > RAID uses FPU. And on K7, basic things like clearing or copying user > pages, or even large memcpy do use FPU too. So, I would expect that when > enabling both, they could happen to be nested. > I think the trick against /this/ is preempt_disable/enable in kernel_fpu/begin/end. But that won't work for Xenomai, of course. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
Jan Kiszka wrote: > Gilles Chanteperdrix wrote: >> Jan Kiszka wrote: >>> Gilles Chanteperdrix wrote: Jan Kiszka wrote: > Hi Gilles, > > I'm currently facing a nasty effect with switchtest over latest git head > (only tested this so far): running it inside my test VM (ie. with > frequent excessive latencies) I get a stalled Linux timer IRQ quite > quickly. System is otherwise still responsive, Xenomai timers are still > being delivered, other Linux IRQs too. switchtest complained about > > "Warning: Linux is compiled to use FPU in kernel-space." > > when it was started. Kernels are 2.6.28.9/ipipe-x86-2.2-07 and > 2.6.29.3/ipipe-x86-2.3-01 (LTTng patched in, but unused), both show the > same effect. > > Seen this before? The warning about Linux being compiled to use FPU in kernel-space means that you enabled soft RAID or compiled for K7, Geode, or any other >>> RAID is on (ordinary server config). >> By the way, I wonder how MMX accelerated software raid works on K7, >> since the way I understand the code, calls to kernel_fpu_begin() can not >> be nested. >> >> If you think they can be nested, then we can make switchtest test fpu in >> Linux kernel-space when these options are enabled. > > Sorry, I haven't looked that close into the in-kernel FPU handling so > far. What users are nested in the standard kernel? Or is it RAID in itself? RAID uses FPU. And on K7, basic things like clearing or copying user pages, or even large memcpy do use FPU too. So, I would expect that when enabling both, they could happen to be nested. -- Gilles. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> Gilles Chanteperdrix wrote: >>> Jan Kiszka wrote: Hi Gilles, I'm currently facing a nasty effect with switchtest over latest git head (only tested this so far): running it inside my test VM (ie. with frequent excessive latencies) I get a stalled Linux timer IRQ quite quickly. System is otherwise still responsive, Xenomai timers are still being delivered, other Linux IRQs too. switchtest complained about "Warning: Linux is compiled to use FPU in kernel-space." when it was started. Kernels are 2.6.28.9/ipipe-x86-2.2-07 and 2.6.29.3/ipipe-x86-2.3-01 (LTTng patched in, but unused), both show the same effect. Seen this before? >>> The warning about Linux being compiled to use FPU in kernel-space means >>> that you enabled soft RAID or compiled for K7, Geode, or any other >> RAID is on (ordinary server config). > > By the way, I wonder how MMX accelerated software raid works on K7, > since the way I understand the code, calls to kernel_fpu_begin() can not > be nested. > > If you think they can be nested, then we can make switchtest test fpu in > Linux kernel-space when these options are enabled. Sorry, I haven't looked that close into the in-kernel FPU handling so far. What users are nested in the standard kernel? Or is it RAID in itself? Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
Jan Kiszka wrote: > Gilles Chanteperdrix wrote: >> Jan Kiszka wrote: >>> Hi Gilles, >>> >>> I'm currently facing a nasty effect with switchtest over latest git head >>> (only tested this so far): running it inside my test VM (ie. with >>> frequent excessive latencies) I get a stalled Linux timer IRQ quite >>> quickly. System is otherwise still responsive, Xenomai timers are still >>> being delivered, other Linux IRQs too. switchtest complained about >>> >>> "Warning: Linux is compiled to use FPU in kernel-space." >>> >>> when it was started. Kernels are 2.6.28.9/ipipe-x86-2.2-07 and >>> 2.6.29.3/ipipe-x86-2.3-01 (LTTng patched in, but unused), both show the >>> same effect. >>> >>> Seen this before? >> The warning about Linux being compiled to use FPU in kernel-space means >> that you enabled soft RAID or compiled for K7, Geode, or any other > > RAID is on (ordinary server config). By the way, I wonder how MMX accelerated software raid works on K7, since the way I understand the code, calls to kernel_fpu_begin() can not be nested. If you think they can be nested, then we can make switchtest test fpu in Linux kernel-space when these options are enabled. -- Gilles. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
On Wed, 2009-05-13 at 15:18 +0200, Jan Kiszka wrote: > Gilles Chanteperdrix wrote: > > Jan Kiszka wrote: > >> Hi Gilles, > >> > >> I'm currently facing a nasty effect with switchtest over latest git head > >> (only tested this so far): running it inside my test VM (ie. with > >> frequent excessive latencies) I get a stalled Linux timer IRQ quite > >> quickly. System is otherwise still responsive, Xenomai timers are still > >> being delivered, other Linux IRQs too. switchtest complained about > >> > >> "Warning: Linux is compiled to use FPU in kernel-space." > >> > >> when it was started. Kernels are 2.6.28.9/ipipe-x86-2.2-07 and > >> 2.6.29.3/ipipe-x86-2.3-01 (LTTng patched in, but unused), both show the > >> same effect. > >> > >> Seen this before? > > > > The warning about Linux being compiled to use FPU in kernel-space means > > that you enabled soft RAID or compiled for K7, Geode, or any other > > RAID is on (ordinary server config). > > > configuration using 3DNow for such simple operations as memcpy. It is > > harmless, it simply means that switchtest can not use fpu in kernel-space. > > > > The bug you have is probably the same as the one described here, which I > > am able to reproduce on my atom: > > https://mail.gna.org/public/xenomai-help/2009-04/msg00200.html > > > > Unfortunately, I for one am working on ARM issues and am not available > > to debug x86 issues. I think Philippe is busy too... > > OK, looks like I got the same flu here. > > Philippe, did you find out any more details in the meantime? Then I'm > afraid I have to pick this up. No, I did not resume this task yet. Working from the powerpc side of the universe here. > > Jan > -- Philippe. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
Gilles Chanteperdrix wrote: > Jan Kiszka wrote: >> Hi Gilles, >> >> I'm currently facing a nasty effect with switchtest over latest git head >> (only tested this so far): running it inside my test VM (ie. with >> frequent excessive latencies) I get a stalled Linux timer IRQ quite >> quickly. System is otherwise still responsive, Xenomai timers are still >> being delivered, other Linux IRQs too. switchtest complained about >> >> "Warning: Linux is compiled to use FPU in kernel-space." >> >> when it was started. Kernels are 2.6.28.9/ipipe-x86-2.2-07 and >> 2.6.29.3/ipipe-x86-2.3-01 (LTTng patched in, but unused), both show the >> same effect. >> >> Seen this before? > > The warning about Linux being compiled to use FPU in kernel-space means > that you enabled soft RAID or compiled for K7, Geode, or any other RAID is on (ordinary server config). > configuration using 3DNow for such simple operations as memcpy. It is > harmless, it simply means that switchtest can not use fpu in kernel-space. > > The bug you have is probably the same as the one described here, which I > am able to reproduce on my atom: > https://mail.gna.org/public/xenomai-help/2009-04/msg00200.html > > Unfortunately, I for one am working on ARM issues and am not available > to debug x86 issues. I think Philippe is busy too... OK, looks like I got the same flu here. Philippe, did you find out any more details in the meantime? Then I'm afraid I have to pick this up. Jan -- Siemens AG, Corporate Technology, CT SE 2 Corporate Competence Center Embedded Linux ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
Re: [Xenomai-core] Troubles with switchtest
Jan Kiszka wrote: > Hi Gilles, > > I'm currently facing a nasty effect with switchtest over latest git head > (only tested this so far): running it inside my test VM (ie. with > frequent excessive latencies) I get a stalled Linux timer IRQ quite > quickly. System is otherwise still responsive, Xenomai timers are still > being delivered, other Linux IRQs too. switchtest complained about > > "Warning: Linux is compiled to use FPU in kernel-space." > > when it was started. Kernels are 2.6.28.9/ipipe-x86-2.2-07 and > 2.6.29.3/ipipe-x86-2.3-01 (LTTng patched in, but unused), both show the > same effect. > > Seen this before? The warning about Linux being compiled to use FPU in kernel-space means that you enabled soft RAID or compiled for K7, Geode, or any other configuration using 3DNow for such simple operations as memcpy. It is harmless, it simply means that switchtest can not use fpu in kernel-space. The bug you have is probably the same as the one described here, which I am able to reproduce on my atom: https://mail.gna.org/public/xenomai-help/2009-04/msg00200.html Unfortunately, I for one am working on ARM issues and am not available to debug x86 issues. I think Philippe is busy too... -- Gilles. ___ Xenomai-core mailing list Xenomai-core@gna.org https://mail.gna.org/listinfo/xenomai-core
