From: Haren Myneni <haren@us.ibm.com>
To: Giuliano Pochini <pochini@shiny.it>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: 2 CPUs, but only one is used
Date: Tue, 19 Dec 2006 20:14:22 -0800 [thread overview]
Message-ID: <4588B89E.3090900@us.ibm.com> (raw)
In-Reply-To: <20061220003545.7053b05c.pochini@shiny.it>
Giuliano Pochini wrote:
>On Sun, 17 Dec 2006 14:41:27 +0100
>Giuliano Pochini <pochini@shiny.it> wrote:
>
>
>
>>I have a dual G4 MDD mac running linux 2.6.19. When I boot with maxcpus=1 and
>>then I issue "echo 1 >/sys/devices/system/cpu/cpu1/online" the second CPU is
>>put online without errors, but it stays idle+wait=100% and of course
>>user+system+nice=0%. It works fine without maxcpus=1. No problems with 2.6.18.
>>
>>I saw that there are some cpu hotplug related changes in 2.6.19, but I have
>>no access to a non-ppc dual cpu box to check if the problem also affects
>>other architectures right now.
>>
>>
>
>I tried to reproduce the problem on an intel box, but I couldn't. /sys
>contains only the cpu0 file if it boots with maxcpus=1.
>
>
On powerpc, when maxcpus=1 is passed, it does not reflect that change in
cpu_possible_map. This possible bitmap is created based on device-tree.
Where as on i386, it does. I.e, cpu_possible_map contains only one cpu.
/sys entries will be created based on cpu_possible_map (I think). Hence,
you noticed only cpu0 entry on Intel box.
- Haren
>
>--
>Giuliano.
>_______________________________________________
>Linuxppc-dev mailing list
>Linuxppc-dev@ozlabs.org
>https://ozlabs.org/mailman/listinfo/linuxppc-dev
>
>
next prev parent reply other threads:[~2006-12-20 4:15 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-12-17 13:41 2 CPUs, but only one is used Giuliano Pochini
2006-12-19 23:35 ` Giuliano Pochini
2006-12-20 4:14 ` Haren Myneni [this message]
2006-12-20 14:16 ` Nathan Lynch
2006-12-21 22:33 ` Giuliano Pochini
2006-12-24 16:58 ` Giuliano Pochini
2006-12-25 5:52 ` Nathan Lynch
2006-12-25 10:53 ` Giuliano Pochini
2006-12-29 16:51 ` Giuliano Pochini
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