>"Aneesh Kumar K.V" < aneesh.ku...@linux.vnet.ibm.com > writes: > >> Phileas Fogg < phileas-f...@mail.ru > writes: >> >>> And another note. >>> I took a look at the MMU chapter in the Cell Architecture handbook and >>> indeed the first 15 bits in VA are treated as 0 by the hardware. >>> >>> Quote: >>> >>> 1. High-order bits above 65 bits in the 80-bit virtual address (VA[0:14]) >>> are not implemented. The hardware always >>> treats these bits as `0'. Software must not set these bits to any other >>> value than `0' or the results are undefined in >>> the PPE. >>> >>> >> >> True, we missed the below part of ISA doc: >> >> ISA doc says >> >> "On implementations that support a virtual address size >> of only n bits, n < 78, bits 0:77-n of the AVA field must be >> zeros. " >> >> The Cell document I found at >> >> >> https://www-01.ibm.com/chips/techlib/techlib.nsf/techdocs/7A77CCDF14FE70D5852575CA0074E8ED/$file/CellBE_Handbook_v1.12_3Apr09_pub.pdf >> >> gives >> >> Virtual Address (VA) Size -> 65 bits >> >> So as per ISA, bits 0:12 should be zero, which should make 0:14 of PTE >> fields zero for Cell. >> >> I will try to do a patch. >> > >Can you try this patch ? > >diff --git a/arch/powerpc/include/asm/mmu-hash64.h >b/arch/powerpc/include/asm/mmu-hash64.h >index 2fdb47a..f01fd9a 100644 >--- a/arch/powerpc/include/asm/mmu-hash64.h >+++ b/arch/powerpc/include/asm/mmu-hash64.h >@@ -381,21 +381,37 @@ extern void slb_set_size(u16 size); > * hash collisions. > */ > >+/* This should go in Kconfig */ >+/* >+ * Be careful with this value. This determines the VSID_MODULUS_* and that >+ * need to be co-prime with VSID_MULTIPLIER* >+ */ >+#if 1 >+#define MAX_VIRTUAL_ADDR_BITS 65 >+#else >+#define MAX_VIRTUAL_ADDR_BITS 66 >+#endif >+/* >+ * One bit is taken by the kernel, only the rest of space is available for the >+ * user space. >+ */ >+#define CONTEXT_BITS (MAX_VIRTUAL_ADDR_BITS - \ >+ (USER_ESID_BITS + SID_SHIFT + 1)) >+#define USER_ESID_BITS 18 >+#define USER_ESID_BITS_1T 6 >+ > /* > * This should be computed such that protovosid * vsid_mulitplier > * doesn't overflow 64 bits. It should also be co-prime to vsid_modulus > */ > #define VSID_MULTIPLIER_256M ASM_CONST(12538073) /* 24-bit prime */ >-#define VSID_BITS_256M 38 >+#define VSID_BITS_256M (CONTEXT_BITS + USER_ESID_BITS + 1) > #define VSID_MODULUS_256M ((1UL<<VSID_BITS_256M)-1) > > #define VSID_MULTIPLIER_1T ASM_CONST(12538073) /* 24-bit prime */ >-#define VSID_BITS_1T 26 >+#define VSID_BITS_1T (CONTEXT_BITS + USER_ESID_BITS_1T + 1) > #define VSID_MODULUS_1T ((1UL<<VSID_BITS_1T)-1) > >-#define CONTEXT_BITS 19 >-#define USER_ESID_BITS 18 >-#define USER_ESID_BITS_1T 6 > > #define USER_VSID_RANGE (1UL << (USER_ESID_BITS + SID_SHIFT)) > >
Testing it with Linux 3.8.0-rc7, it looks good so far under heavy hard disk usage.
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