On Tue, Feb 06, 2024 at 10:09:59AM -0800, Christoph Lameter (Ampere) wrote: > Can we get this merged for 6.9? The patch has been around for awhile now. > > > > Ampere Computing develops high end ARM processor that support an ever > increasing number of processors. The default 256 processors are > not enough for our newer products. The default is used by > distros and therefore our customers cannot use distro kernels because > the number of processors is not supported. > > One of the objections against earlier patches to increase the limit > was that the memory use becomes too high. There is a feature called > CPUMASK_OFFSTACK that configures the cpumasks in the kernel to be > dynamically allocated. This was used in the X86 architecture in the > past to enable support for larger CPU configurations up to 8k cpus. > > With that is becomes possible to dynamically size the allocation of > the cpu bitmaps depending on the quantity of processors detected on > bootup. > > This patch enables that logic if more than 256 processors > are configured and increases the default to 512 processors. > > Further increases may be needed if ARM processor vendors start > supporting more processors. Given the current inflationary trends > in core counts from multiple processor manufacturers this may occur. > > Tested-by: Eric Mackay <eric.mackay@xxxxxxxxxx> Reviewed-by: Russell King (Oracle) <rmk+kernel@xxxxxxxxxxxxxxx> Thanks! > Signed-off-by: Christoph Lameter (Ampere) <cl@xxxxxxxxx> -- RMK's Patch system: https://www.armlinux.org.uk/developer/patches/ FTTP is here! 80Mbps down 10Mbps up. Decent connectivity at last!
