Re: performance differences: "maxcpus=1" vs. "echo 0 > /sys/devices/system/cpu/cpu1/online" | KernelTrap

Re: performance differences: "maxcpus=1" vs. "echo 0 > /sys/devices/system/cpu/cpu1/online"

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From: Luciano Rocha <luciano@...>

To: Michael Meyer <mike65134@...>

Cc: <linux-kernel@...>

Subject: Re: performance differences: "maxcpus=1" vs. "echo 0 > /sys/devices/system/cpu/cpu1/online"

Date: Tuesday, March 25, 2008 - 10:08 am

On Tue, Mar 25, 2008 at 02:47:50PM +0100, Michael Meyer wrote:
quoted text> Hi,=20
>=20
> what is the difference between booting a dual core
> machine with "maxcpus=3D1" or by deactivating the second
> core at run time with "echo 0 >
> /sys/devices/system/cpu/cpu1/online"?

maxcpus=3D1 should turn off the SMP alternative and switch to UP only,
optimising some locks and instructions.

--=20
Luciano Rocha <luciano@eurotux.com>
Eurotux Inform=E1tica, S.A. <http://www.eurotux.com/>

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Messages in current thread:

performance differences: "maxcpus=1" vs. "echo 0 > /sys/d..., Michael Meyer, (Tue Mar 25, 9:47 am)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Bernd Eckenfels, (Sat Mar 29, 7:22 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Pavel Machek, (Fri Mar 28, 9:59 am)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Michael Meyer, (Sat Mar 29, 4:55 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Pavel Machek, (Sat Mar 29, 5:22 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Michael Meyer, (Sat Mar 29, 6:16 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Pavel Machek, (Wed Apr 2, 7:31 am)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Luciano Rocha, (Tue Mar 25, 10:08 am)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Andi Kleen, (Tue Mar 25, 1:16 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Pavel Machek, (Fri Mar 28, 10:00 am)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Michael Meyer, (Tue Mar 25, 1:23 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Len Brown, (Tue Mar 25, 7:27 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Michael Meyer, (Wed Mar 26, 3:26 am)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Wander Winkelhorst, (Tue Mar 25, 1:49 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Michael Meyer, (Tue Mar 25, 1:56 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Andi Kleen, (Tue Mar 25, 1:57 pm)

Re: performance differences: "maxcpus=1" vs. "echo 0 > /s..., Michael Meyer, (Tue Mar 25, 12:38 pm)

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