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Subject: Re: [hwloc-devel] hwloc on power7
From: Brice Goglin (Brice.Goglin_at_[hidden])
Date: 2010-08-05 01:08:09


Power7 topology isn't properly reported by old kernels. We've been said
that it works fine with 2.6.34. I am not sure which commit fixed this. I
don't see many commits talk about Power7 topology between 2.6.32 and
2.6.34, so it may be this one (from 2.6.34):

commit 4b83c330b4d38e869111bda6e9077d4f61ed974a
Author: Anton Blanchard <anton_at_[hidden]>
Date: Wed Apr 7 15:33:44 2010 +0000

    powerpc/numa: Add form 1 NUMA affinity
    
    Firmware changed the way it represents memory and cpu affinity on POWER7.
    Unfortunately the old method now caps the topology to work around issues
    with legacy operating systems. For Linux to get the correct topology we
    need to use the new form 1 affinity information.
    
    We set the form 1 field in the client architecture, and if we see "1" in the
    ibm,associativity-form property firmware supports form 1 affinity and
    we should look at the first field in the ibm,associativity-reference-points
    array. If not we use the second field as we always have.
    
    Signed-off-by: Anton Blanchard <anton_at_[hidden]>
    Signed-off-by: Benjamin Herrenschmidt <benh_at_[hidden]>

Maybe some distros should backport it...

Brice

Le 05/08/2010 00:19, Jirka Hladky a écrit :
> Hi,
>
> I just got access to one POWER7 box. Both hwloc 1.0.2 and latest hwloc 1.1
> seem to have problems to detect the sockets correctly.
>
> It's IBM 8406-71Y server equipped with only one socket. On the chip there are
> 8 cores. lstopo seems to be wrong here, reporting 8 sockets.
>
> I'm not sure if this problem arose in linux kernel or it's bug in lstopo code.
> Does anybody else tried to run hwloc on POWER7?
>
> Thanks
> Jirka
>
>
> Kernel: 2.6.32-54.el6.ppc64
>
> root_at_[hidden]: /tmp/hwloc-1.1a1r2387/utils
> $ ./lstopo
> Machine (7616MB)
> Socket #0 + L3 #0 (4096KB) + L2 #0 (256KB) + L1 #0 (32KB) + Core #0
> PU #0 (phys=0)
> PU #1 (phys=1)
> PU #2 (phys=2)
> PU #3 (phys=3)
> Socket #1 + L3 #1 (4096KB) + L2 #1 (256KB) + L1 #1 (32KB) + Core #1
> PU #4 (phys=4)
> PU #5 (phys=5)
> PU #6 (phys=6)
> PU #7 (phys=7)
> Socket #2 + L3 #2 (4096KB) + L2 #2 (256KB) + L1 #2 (32KB) + Core #2
> PU #8 (phys=8)
> PU #9 (phys=9)
> PU #10 (phys=10)
> PU #11 (phys=11)
> Socket #3 + L3 #3 (4096KB) + L2 #3 (256KB) + L1 #3 (32KB) + Core #3
> PU #12 (phys=12)
> PU #13 (phys=13)
> PU #14 (phys=14)
> PU #15 (phys=15)
> Socket #4 + L3 #4 (4096KB) + L2 #4 (256KB) + L1 #4 (32KB) + Core #4
> PU #16 (phys=16)
> PU #17 (phys=17)
> PU #18 (phys=18)
> PU #19 (phys=19)
> Socket #5 + L3 #5 (4096KB) + L2 #5 (256KB) + L1 #5 (32KB) + Core #5
> PU #20 (phys=20)
> PU #21 (phys=21)
> PU #22 (phys=22)
> PU #23 (phys=23)
> Socket #6 + L3 #6 (4096KB) + L2 #6 (256KB) + L1 #6 (32KB) + Core #6
> PU #24 (phys=24)
> PU #25 (phys=25)
> PU #26 (phys=26)
> PU #27 (phys=27)
> Socket #7 + L3 #7 (4096KB) + L2 #7 (256KB) + L1 #7 (32KB) + Core #7
> PU #28 (phys=28)
> PU #29 (phys=29)
> PU #30 (phys=30)
> PU #31 (phys=31)
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