Messages in this thread Patch in this message | | | Date | Sun, 27 Apr 2003 04:23:46 +0200 | From | Andi Kleen <> | Subject | [PATCH] Support worst case cache line sizes as config option |
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This mirrors a change that has been in the SuSE/aa 2.4 kernel for a long time.
For a generic binary kernel you really want to assume the worst case cache line size. That's the P4's 128 byte currently.
The overhead of having the cache line size bigger on other CPUs is not that bad, but if it is too small it will cost you dearly on SMP and even a bit on UP in device drivers.
This patch adds a new CONFIG_X86_GENERIC option for this. It currently only forces 128byte cache lines, but could be used for more in the future.
diff -u linux-gencpu/arch/i386/Kconfig-o linux-gencpu/arch/i386/Kconfig --- linux-gencpu/arch/i386/Kconfig-o 2003-04-27 02:40:32.000000000 +0200 +++ linux-gencpu/arch/i386/Kconfig 2003-04-27 03:50:08.000000000 +0200 @@ -273,6 +273,13 @@ endchoice +config X86_GENERIC + bool "Generic x86 support" + help + Include some tuning for non selected x86 CPUs too. + when it has moderate overhead. This is intended for generic + distributions kernels. + # # Define implied options from the CPU selection here # @@ -288,10 +295,10 @@ config X86_L1_CACHE_SHIFT int + default "7" if MPENTIUM4 || X86_GENERIC default "4" if MELAN || M486 || M386 default "5" if MWINCHIP3D || MWINCHIP2 || MWINCHIPC6 || MCRUSOE || MCYRIXIII || MK6 || MPENTIUMIII || MPENTIUMII || M686 || M586MMX || M586TSC || M586 || MVIAC3_2 default "6" if MK7 || MK8 - default "7" if MPENTIUM4 config RWSEM_GENERIC_SPINLOCK bool - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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