Messages in this thread | | | Date | Mon, 8 Sep 2014 15:28:43 +0200 | From | Robert Richter <> | Subject | Re: [PATCH] arm64, defconfig: Increase NR_CPUS default to 64 |
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On 08.09.14 15:00:47, Arnd Bergmann wrote: > On Monday 08 September 2014 13:44:48 Robert Richter wrote: > > From: Robert Richter <rrichter@cavium.com> > > > > Raising the current maximum limit to 64. This is needed for Cavium's > > Thunder systems that will have at least 48 cores per die. > > > > The change keeps the current memory footprint in cpu mask structures. > > It does not break existing code. Setting the maximum to 64 cpus still > > boots systems with less cpus. > > > > Mark's Juno happily booted with a NR_CPUS=64 kernel. > > > > Tested on our Thunder system with 48 cores. We could see interrupts to > > all cores. > > > > Cc: Radha Mohan Chintakuntla <rchintakuntla@cavium.com> > > Cc: Mark Rutland <mark.rutland@arm.com> > > Signed-off-by: Robert Richter <rrichter@cavium.com> > > > > Acked-by: Arnd Bergmann <arnd@arndb.de> > > FWIW, have you tried what happens when you increase the number further? > We have architectures on which we support thousands of CPUs, so I wonder > if there is a point at which this stops working on ARM64. > > Are you able to compile and boot a kernel built with e.g. NR_CPUS=256 or > 4096 on your hardware?
We haven't tried this so far, but it's definitely on our list testing this.
-Robert
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