[Crash-utility] FW: Number of cpus on ARM

[Karlsson, Jan]

Hi

I have tried the arm_get_smp_cpus implementation given below and it works fine on all examples I have tested.

What about ARM64? Same update?

Jan

Jan Karlsson
Senior Software Engineer
System Assurance

Sony Mobile Communications
Tel: +46 703 062 174
jan.karlsson at sonymobile.com

sonymobile.com



-----Original Message-----
From: crash-utility-bounces at redhat.com [mailto:crash-utility-bounces at redhat.com] On Behalf Of Dave Anderson
Sent: den 15 oktober 2014 15:36
To: Discussion list for crash utility usage, maintenance and development
Subject: Re: [Crash-utility] FW: Number of cpus on ARM



----- Original Message -----
> 
> 
> ----- Original Message -----
> > 
> > Hello
> > 
> > That would be a possibility but I prefer if crash can calculate the 
> > correct number of cpus itself.
> >
>  
> Right, the --cpus option is only there as a workaround.
> 
> > If we just want to set the number of cpus to the number of cpus 
> > present, then the function “get_cpus_present()” could probably be used.
> 
> I prefer your patch copying ARM64.  You could throw get_cpus_present() 
> in there, but it wouldn't apply to 2.6.29 and earlier kernels.

I take that back -- I've got an ARM ramdump where they take all cpus offline before taking the dump.  How about this:

static int
arm_get_smp_cpus(void)
{
        int cpus;

        if (cpus = get_cpus_present())
                return cpus;
        else
                return MAX(get_cpus_online(), get_highest_cpu_online()+1); }

It covers all bases with all the sample dumpfiles I've got on hand.

Dave


 
> Dave
>  
> > 
> > 
> > Jan
> > 
> > 
> > 
> > Jan Karlsson
> > 
> > Senior Software Engineer
> > 
> > System Assurance
> > 
> > 
> > 
> > Sony Mobile Communications
> > 
> > Tel: +46 703 062 174
> > 
> > jan.karlsson at sonymobile.com
> > 
> > 
> > 
> > sonymobile.com
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > From: crash-utility-bounces at redhat.com 
> > [mailto:crash-utility-bounces at redhat.com] On Behalf Of Arun KS
> > Sent: den 15 oktober 2014 11:57
> > To: Discussion list for crash utility usage, maintenance and 
> > development
> > Subject: Re: [Crash-utility] FW: Number of cpus on ARM
> > 
> > 
> > 
> > 
> > 
> > Hello Jan,
> > 
> > 
> > 
> > 
> > 
> > Can you try with option --cpus=4 passed when your start the crash.
> > 
> > 
> > I used 4 here because i have 4 cores.
> > 
> > 
> > 
> > 
> > 
> > Thanks,
> > 
> > 
> > Arun
> > 
> > 
> > 
> > 
> > 
> > On Wed, Oct 15, 2014 at 2:49 PM, Karlsson, Jan < 
> > Jan.Karlsson at sonymobile.com
> > > wrote:
> > 
> > 
> > Hi
> > 
> > 
> > 
> > Unfortunately I found another older example where my patch below did 
> > not work.
> > 
> > In that one only cpu 0 where online but 0,1,2,3 where active. So maybe:
> > 
> > 
> > 
> > return MAX(get_cpus_active(), get_highest_cpu_online()+1);
> > 
> > 
> > 
> > might work better. Someone with better knowledge about this than I 
> > have should look at the problem.
> > 
> > 
> > 
> > Jan
> > 
> > 
> > 
> > 
> > Jan Karlsson
> > 
> > Senior Software Engineer
> > 
> > System Assurance
> > 
> > 
> > 
> > Sony Mobile Communications
> > 
> > Tel: +46 703 062 174
> > 
> > jan.karlsson at sonymobile.com
> > 
> > 
> > 
> > sonymobile.com
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > From: Karlsson, Jan
> > Sent: den 15 oktober 2014 10:49
> > To: Discussion list for crash utility usage, maintenance and 
> > development
> > Subject:
> > 
> > 
> > 
> > 
> > Hi
> > 
> > 
> > 
> > I have seen a problem when it comes to the number of cpus for ARM 
> > (32-bits).
> > 
> > 
> > 
> > static int
> > 
> > arm_get_smp_cpus(void)
> > 
> > {
> > 
> > return MAX(get_cpus_active(), get_cpus_online());
> > 
> > }
> > 
> > 
> > 
> > In one of my example, “help –k” gives me:
> > 
> > cpu_possible_map: 0 1 2 3
> > 
> > cpu_present_map: 0 1 2 3
> > 
> > cpu_online_map: 0 3
> > 
> > cpu_active_map: 3
> > 
> > 
> > 
> > So the number of cpus will become 2. However there are code in a 
> > number of places that will then only accept cpu 0 and 1 as cpus to handle.
> > 
> > 
> > 
> > When I changed to code to be the same as for ARM64 things worked as
> > expected:
> > 
> > 
> > 
> > static int
> > 
> > arm_get_smp_cpus(void)
> > 
> > {
> > 
> > return MAX(get_cpus_online(), get_highest_cpu_online()+1);
> > 
> > }
> > 
> > 
> > 
> > Jan
> > 
> > 
> > 
> > Jan Karlsson
> > 
> > Senior Software Engineer
> > 
> > System Assurance
> > 
> > 
> > 
> > Sony Mobile Communications
> > 
> > Tel: +46 703 062 174
> > 
> > jan.karlsson at sonymobile.com
> > 
> > 
> > 
> > sonymobile.com
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > 
> > --
> > Crash-utility mailing list
> > Crash-utility at redhat.com
> > https://www.redhat.com/mailman/listinfo/crash-utility
> > 
> > 
> > 
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