Single Address Space o RW RO EX NO o Kernel vfat.o Single - PowerPoint PPT Presentation

Single Address Space o RW RO EX NO o Kernel vfat.o

Single Address Space o RW RO EX o NO Kernel vfat.o

Single Address Space RW RO mprotect o EX NO Kernel (PD-ID=0) vfat.o (PD-ID=1)

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Seg. VA Linear TLB PA Regs (opt.) Addr. Protection Fault

VA Linear TLB PA (opt.) Addr. Protection MMP Fault o

CPU Protection Domain ID (PD-ID) Lookaside Perm. Table Base Buffer Memory Refill Permissions Permissions Table Table

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3 rd level – 4B sub-blk 2 nd level 1 st level 256B sub-blocks P … 256KB sub-blocks D D D D P … D D P … … D D P P D … 2 bits per sub-block … D

3 rd level – 4B sub-blk 2 nd level 1 st level 256B sub-blocks P … 256KB sub-blocks D D D D P … D D P … D D D P D … 2 bits per sub-block … D

3 rd level – 4B sub-blk 2 nd level 1 st level 256B sub-blocks P … 256KB sub-blocks D D D D P … D D P … D D 0-256KB no perm. D D D … 2 bits per sub-block D

Naive Memory Compressed Entries Words Entries o o

CPU Protection Protection Domain ID (PD-ID) Lookaside Lookaside Perm. Table Base Buffer Buffer Memory Refill Permissions Table

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Instruction RS IMM OP PLB Addr Tag Perm Tab. Ent. PD-ID Regs + Hit? No Access Yes Perm. Table in Read/Write Memory OK Fault

o vs. D 1 st level or 2 nd level

o o PLB (Xs are don’t-care bits) Tag (26 bits) Perm. Table Ent. PD-ID 1 st level ent. 0 0x07 XX XX D 2 nd level ent. 0 0x09 87 XX D 3 rd level ent. 0 0x09 20 58 o

CPU Sidecars Sidecars refill Protection Domain ID (PD-ID) Lookaside Perm. Table Base Buffer Memory Refill Permissions Table

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Instruction RS IMM OP Sidecar Regs Addr Base Bound Perm Regs + Base ≥ Addr. ≥ Bound Yes No Access Read/Write PLB OK Fault

o gcc –O3 (egcs-1.0.3) o o

60 Entry PLB 60 Entry TLB Ref. to MMP tables 0.00-0.56% 0.00-2.59% Application refs Table size / App. data 0.04-0.62% 0.02-0.22% Sidecar miss rate 1-40%(12%) -- o

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60 Entry PLB Ref. to MMP tables 0.0- 7.5% (0.1-19%) Application refs Table size / App. data 0.4- 8.3% Table references 0.6-11.0% eliminated by sidecars o o o o

MMP TLB VA Linear PA Trans (opt.) Addr. Unit Protection MMP Fault o o

Single Address Space Body 0 Body 1 Head 0 Body 0 Head 1 Body 1 Kernel a user

o Variable sized 3 rd level table pool of translation New ptr. type PT records … +0x9583F

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