Re: 2.4.21 on Itanium2: floating-point assist fault at ip 400000000062ada1, isr 0000020000000008

["Ulrich Windl" <Ulrich.Windl@rz.uni-regensburg.de>]

OK,

thanks guys for the answers: It seems to be a hint that an instruction can't 
be done in hardware, but has to be emulated instead. I tried to find the 
offending code, and I was surprised that is't not a complicated function:

                br.few 0x400000000062aca0 <ab_CompManyEq+384>
0x400000000062ad70 <ab_CompManyEq+592>: [MII]       nop.m 0x0
0x400000000062ad71 <ab_CompManyEq+593>:             zxt4 r14=r44;;
0x400000000062ad72 <ab_CompManyEq+594>:             add r15=r35,r14
0x400000000062ad80 <ab_CompManyEq+608>: [MMI]       add r14=r34,r14;;
0x400000000062ad81 <ab_CompManyEq+609>:             ldfd f7=[r14]
0x400000000062ad82 <ab_CompManyEq+610>:             nop.i 0x0
0x400000000062ad90 <ab_CompManyEq+624>: [MMI]       ldfd f6=[r15];;
0x400000000062ad91 <ab_CompManyEq+625>:             nop.m 0x0
0x400000000062ad92 <ab_CompManyEq+626>:             nop.i 0x0
0x400000000062ada0 <ab_CompManyEq+640>: [MFI]       nop.m 0x0
0x400000000062ada1 <ab_CompManyEq+641>:             fcmp.eq.s0 p7,p6=f7,f6 <<<
0x400000000062ada2 <ab_CompManyEq+642>:             nop.i 0x0;;
0x400000000062adb0 <ab_CompManyEq+656>: [MIB]       nop.m 0x0
0x400000000062adb1 <ab_CompManyEq+657>:             nop.i 0x0

(when attaching to the process with gdb)

Thanks and regards,
Ulrich

On 31 Mar 2004 at 19:00, Denis Vlasenko wrote:

> On Wednesday 31 March 2004 15:16, Ulrich Windl wrote:
> > Hello,
> >
> > I did try to find an answer is SuSE's support database, not in SAP's
> > support database, and also did search Google, but could not find an answer:
> >
> > We run SuSE Linux Enterprise Server 8 (SLES8) on a HP rx4640 Itanium2
> > server with 2 CPUs (family: Itanium 2, model: 1, revision: 5, archrev: 0).
> >
> > In syslog is do see periodic kernel messages (with no implicit priority)
> > that read:
> >
> > dw.sapC11_DVS02(14393): floating-point assist fault at ip 400000000062ada1,
> > isr 0000020000000008
> >
> > ("dw.sapC11_DVS02" is a SAP R/3 work process (46D_EXT, patch 1754, for
> > those who care)
> >
> > Can anybody explain what this message means? Is it an application problem,
> > or is it a kernel problem?
> 
>         static int fpu_swa_count = 0;
>         static unsigned long last_time;
> ...
>         if (jiffies - last_time > 5*HZ)
>                 fpu_swa_count = 0;
>         if ((fpu_swa_count < 4) && !(current->thread.flags & IA64_THREAD_FPEMU_NOPRINT)) {
>                 last_time = jiffies;
>                 ++fpu_swa_count;
>                 printk(KERN_WARNING "%s(%d): floating-point assist fault at ip %016lx, isr %016lx\n",
>                        current->comm, current->pid, regs->cr_iip + ia64_psr(regs)->ri, isr);
>         }
> 
> kernel says that you have them too frequently, which probably
> impairs efficiency. It's a hint to programmer.
> --
> vda
> 
>