学习内容 介绍地址空间和页表相关的内容.任务调度下次课说.
如何在一个主任务的基础上启用一个子任务,让他完成一系列的工作
启用一个单任务的基础上能够开两个任务,然后完成两个任务之间的通信
makefile的原理 调用是这样实现的:
首先是Makefile里的:
它需要有build和justrun这两个虚拟文件 .
再去看build:
1 build: $(OUT_DIR) $(OUT_BIN)
需要的是OUT_DIR和OUT_BIN这两个实体文件 .
创建它们两个的文件在scripts/make/build.mk:
1 2 3 4 5 $(OUT_DIR) : $(call run_cmd,mkdir,-p $@ ) $(OUT_BIN) : _cargo_build $(OUT_ELF) $(call run_cmd,$(OBJCOPY) ,$(OUT_ELF) --strip -all -O binary $@ )
这里调用的run_cmd在scripts/make/utils.mk:
1 2 3 4 5 6 7 8 9 10 11 GREEN_C := \033[92;1m CYAN_C := \033[96;1m YELLOW_C := \033[93;1m GRAY_C := \033[90m WHITE_C := \033[37m END_C := \033[0m define run_cmd @printf '$(WHITE_C) $(1)$(END_C) $(GRAY_C) $(2)$(END_C)\n ' @$(1) $(2) endef
这里$(1)和$(2)表示接受的是两个参数 .
这个是两个操作,
通过颜色参数 把要执行的命令输出出来(第一行)
第二行相当于执行接受的两个参数
$@是代表这个虚拟文件 本身
其实这一套操作下来就是创建这个OUT_DIR这个名字的文件夹.
在Makefile中:
1 2 3 4 5 6 A ?= tour/u_1_0 APP ?= $(A) ... ... OUT_DIR ?= $(APP)
这时候把目光转回OUT_BIN.它在scripts/make/build.mk中:
1 2 $(OUT_BIN) : _cargo_build $(OUT_ELF) $(call run_cmd,$(OBJCOPY) ,$(OUT_ELF) --strip -all -O binary $@ )
那么它的构建需要虚拟文件 _cargo_build和实体文件OUT_ELF.
那么_cargo_build的功能也是先进行输出 ,随后调用cargo_build:
1 2 3 4 5 6 7 8 _cargo_build: @printf " $(GREEN_C) Building$(END_C) App: $(APP_NAME) , Arch: $(ARCH) , Platform: $(PLATFORM_NAME) , App type: $(APP_TYPE)\n " ifeq ($(APP_TYPE) , rust) $(call cargo_build,$(APP) ,$(AX_FEAT) $(LIB_FEAT) $(APP_FEAT) ) @cp $(rust_elf) $(OUT_ELF) else ifeq ($(APP_TYPE) , c) $(call cargo_build,ulib/axlibc,$(AX_FEAT) $(LIB_FEAT) ) endif
那么cargo_build在scripts/make/cargo.mk里:
1 2 3 define cargo_build $(call run_cmd,cargo -C $(1) build,$(build_args) --features "$(strip $(2))" ) endef
由于我们知道run_cmd是什么套路了,因此这边就是执行cargo来构建一个elf文件.
回到OUT_BIN这边,得到两个所需文件之后,通过OBJCOPY ?= rust-objcopy --binary-architecture=$(ARCH)(在Makefile)中定义,把elf多余的信息头去掉,只留下可执行二进制文件 :
1 2 $(OUT_BIN) : _cargo_build $(OUT_ELF) $(call run_cmd,$(OBJCOPY) ,$(OUT_ELF) --strip -all -O binary $@ )
最后回到justrun,它调用了run_qemu(在scripts/make/qemu.mk),
1 2 3 4 define run_qemu @printf " $(CYAN_C) Running$(END_C) on qemu...\n" $(call run_cmd,$(QEMU) ,$(qemu_args-y) ) endef
这里调用了QEMU,是依赖于ARCH ?= riscv64(在Makefile):
1 QEMU := qemu-system-$(ARCH)
这里调用了qemu_args-y,同样是依赖于ARCH的这里不赘述:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 qemu_args-x86_64 := \ -machine q35 \ -kernel $(OUT_ELF) qemu_args-riscv64 := \ -machine virt \ -bios default \ -kernel $(OUT_BIN) qemu_args-aarch64 := \ -cpu cortex-a72 \ -machine virt \ -kernel $(OUT_BIN) qemu_args-y := -m 128M -smp $(SMP) $(qemu_args-$(ARCH) )
ReadPFlash 本节目标：
引入页表管理组件，通过地址空间重映射，支持设备MMIO
地址空间概念，重映射的意义，页表机制
希望能从PFlash把应用的数据加载进来,以为运行后边的程序做基础.
实验没有paging时的情况 正常运行 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 OpenSBI v0.9 ____ _____ ____ _____ / __ \ / ____| _ \_ _| | | | |_ __ ___ _ __ | (___ | |_) || | | | | | '_ \ / _ \ '_ \ \___ \| _ < | | | |__| | |_) | __/ | | |____) | |_) || |_ \____/| .__/ \___|_| |_|_____/|____/_____| | | |_| Platform Name : riscv-virtio,qemu Platform Features : timer,mfdeleg Platform HART Count : 1 Firmware Base : 0x80000000 Firmware Size : 100 KB Runtime SBI Version : 0.2 Domain0 Name : root Domain0 Boot HART : 0 Domain0 HARTs : 0* Domain0 Region00 : 0x0000000080000000-0x000000008001ffff () Domain0 Region01 : 0x0000000000000000-0xffffffffffffffff (R,W,X) Domain0 Next Address : 0x0000000080200000 Domain0 Next Arg1 : 0x0000000087000000 Domain0 Next Mode : S-mode Domain0 SysReset : yes Boot HART ID : 0 Boot HART Domain : root Boot HART ISA : rv64imafdcsu Boot HART Features : scounteren,mcounteren,time Boot HART PMP Count : 16 Boot HART PMP Granularity : 4 Boot HART PMP Address Bits: 54 Boot HART MHPM Count : 0 Boot HART MHPM Count : 0 Boot HART MIDELEG : 0x0000000000000222 Boot HART MEDELEG : 0x000000000000b109 d8888 .d88888b. .d8888b. d88888 d88P" "Y88b d88P Y88b d88P888 888 888 Y88b. d88P 888 888d888 .d8888b .d88b. 888 888 "Y888b. d88P 888 888P" d88P" d8P Y8b 888 888 "Y88b. d88P 888 888 888 88888888 888 888 "888 d8888888888 888 Y88b. Y8b. Y88b. .d88P Y88b d88P d88P 888 888 "Y8888P "Y8888 "Y88888P" "Y8888P" arch = riscv64 platform = riscv64-qemu-virt target = riscv64gc-unknown-none-elf smp = 1 build_mode = release log_level = warn Try to access dev region [0xFFFFFFC022000000], got 0x646C6670 Got pflash magic: pfld
pfld在哪?
在scripts/make/utils.mk中,在pflash中写入了pfld:
1 2 3 4 5 6 7 8 9 10 define mk_pflash @RUSTFLAGS="" cargo build -p origin --target riscv64gc-unknown-none-elf --release @rust-objcopy --binary-architecture=riscv64 --strip-all -O binary ./target/riscv64gc-unknown-none-elf/release/origin /tmp/origin.bin @printf "pfld\00\00\00\01" > /tmp/prefix.bin @printf "%08x" `stat -c "%s" /tmp/origin.bin` | xxd -r -ps > /tmp/size.bin @cat /tmp/prefix.bin /tmp/size.bin > /tmp/head.bin @dd if=/dev/zero of=./$(1) bs=1M count=32 @dd if=/tmp/head.bin of=./$(1) conv=notrunc @dd if=/tmp/origin.bin of=./$(1) seek=16 obs=1 conv=notrunc endef
那么这个在哪里调用呢?答案是没有调用 .
我们是直接pull下来的,如果调用make pflash_img就会重新生成 它.
在scripts/make/qemu.mk里:
1 2 3 4 5 6 7 8 9 10 qemu_args-y := -m 128M -smp $(SMP) $(qemu_args-$(ARCH) ) qemu_args-$(PFLASH) += \ -drive if=pflash,file=$(CURDIR) /$(PFLASH_IMG) ,format=raw,unit=1 ... ... define run_qemu @printf " $(CYAN_C) Running$(END_C) on qemu...\n" $(call run_cmd,$(QEMU) ,$(qemu_args-y) ) endef
而在Makefile里PFLASH被指定为y.这样就会在运行qemu的时候加上pflash.img这个文件.
没有指定paging的情况 代码:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 #![cfg_attr(feature = "axstd" , no_std)] #![cfg_attr(feature = "axstd" , no_main)] #[macro_use] #[cfg(feature = "axstd" )] extern crate axstd as std;use core::{mem, str };use std::os::arceos::modules::axhal::mem::phys_to_virt;const PFLASH_START: usize = 0x2200_0000 ;#[cfg_attr(feature = "axstd" , no_mangle)] fn main let va = phys_to_virt(PFLASH_START.into()).as_usize(); let ptr = va as *const u32 ; unsafe { println! ("Try to access dev region [{:#X}], got {:#X}" , va, *ptr); let magic = mem::transmute::<u32 , [u8 ; 4 ]>(*ptr); println! ("Got pflash magic: {}" , str ::from_utf8(&magic).unwrap()); } }
这里需要看下一节关于PFlash的部分,因为这时候需要访问外设,在没有remap的时候是1G的恒等映射 ,外设没有映射到地址空间中,因此报错.
一开始只映射了物理空间的0x8000_0000到0xC000_0000.
这里访问的物理地址是0x2200_0000,本来就不属于刚刚提到的物理空间,因此通过恒等映射平移也得不到恒等映射之后的虚拟地址.
产生的log:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 OpenSBI v0.9 ____ _____ ____ _____ / __ \ / ____| _ \_ _| | | | |_ __ ___ _ __ | (___ | |_) || | | | | | '_ \ / _ \ '_ \ \___ \| _ < | | | |__| | |_) | __/ | | |____) | |_) || |_ \____/| .__/ \___|_| |_|_____/|____/_____| | | |_| Platform Name : riscv-virtio,qemu Platform Features : timer,mfdeleg Platform HART Count : 1 Firmware Base : 0x80000000 Firmware Size : 100 KB Runtime SBI Version : 0.2 Domain0 Name : root Domain0 Boot HART : 0 Domain0 HARTs : 0* Domain0 Region00 : 0x0000000080000000-0x000000008001ffff () Domain0 Region01 : 0x0000000000000000-0xffffffffffffffff (R,W,X) Domain0 Next Address : 0x0000000080200000 Domain0 Next Arg1 : 0x0000000087000000 Domain0 Next Mode : S-mode Domain0 SysReset : yes Boot HART ID : 0 Boot HART Domain : root Boot HART ISA : rv64imafdcsu Boot HART Features : scounteren,mcounteren,time Boot HART PMP Count : 16 Boot HART PMP Granularity : 4 Boot HART PMP Address Bits: 54 Boot HART MHPM Count : 0 Boot HART MHPM Count : 0 Boot HART MIDELEG : 0x0000000000000222 Boot HART MEDELEG : 0x000000000000b109 d8888 .d88888b. .d8888b. d88888 d88P" "Y88b d88P Y88b d88P888 888 888 Y88b. d88P 888 888d888 .d8888b .d88b. 888 888 "Y888b. d88P 888 888P" d88P" d8P Y8b 888 888 "Y88b. d88P 888 888 888 88888888 888 888 "888 d8888888888 888 Y88b. Y8b. Y88b. .d88P Y88b d88P d88P 888 888 "Y8888P "Y8888 "Y88888P" "Y8888P" arch = riscv64 platform = riscv64-qemu-virt target = riscv64gc-unknown-none-elf smp = 1 build_mode = release log_level = warn Try to access dev region [0xFFFFFFC022000000], got [ 2.002842 0 axruntime::lang_items:5] panicked at modules/axhal/src/arch/riscv/trap.rs:55:13: Unhandled trap Exception(LoadFault) @ 0xffffffc080203fa6: TrapFrame { regs: GeneralRegisters { ra: 0xffffffc08020376c, sp: 0xffffffc0802499f0, gp: 0x0, tp: 0x0, t0: 0x3f, t1: 0x23, t2: 0x5, s0: 0xffffffc080249a80, s1: 0xffffffc080249c60, a0: 0xffffffc022000000, a1: 0xffffffc080249a80, a2: 0x0, a3: 0xffffffc080203f9e, a4: 0x2, a5: 0xffffffc080202b76, a6: 0xa, a7: 0x1, s2: 0x2, s3: 0xffffffc080249bc0, s4: 0xffffffc080249bf0, s5: 0x38, s6: 0xffffffc080205098, s7: 0x2, s8: 0x1, s9: 0x24000, s10: 0x2, s11: 0xffffffc08026e000, t3: 0x23, t4: 0x3a, t5: 0x5000, t6: 0x55555555, }, sepc: 0xffffffc080203fa6, sstatus: 0x8000000000006100, }
分支名称:tour_u_3_0_no_paging
MAP和REMAP ArceOS Unikernel包括两阶段地址空间映射，
上一节说了启动之后需要remap,这样才可以实现重映射.
那么就需要打开paging.
初始化的线性页表 其实是创建了两个映射,相当于拿前一个恒等映射做了跳板,因为要求开启MMU之后仍然可以以原来的物理地址正常访问.
#TODO
后续创建多级页表 #TODO
PFlash 是一个模拟闪存磁盘.QEMU启动的时候会自动从内存中加载内容到固定的MMIO区域.
读操作是不需要驱动的,但是写是需要驱动的.
目前我们只需要读 ,只要加载成功即可.
物理地址空间
外设被映射 到一个物理地址空间里边.
注意:linker_riscv64-qemu-virt.lds,段布局都是听的它的.
分页 类似于rCore的三级页表,我们实验中用的也是SV39.
分页阶段1-恒等映射+偏移 我们希望sbi和kernel都保存在高地址空间.
开局的时候把虚拟空间内的地址和物理空间内的地址完全对应上.
给指针寄存器pc栈寄存器sp加偏移,这里的偏移是0xffff_ffc0_0000_0000.
sbi还是放在0x8000_0000,kernel还是放在0x8020_0000.
那么在这个情况下其实已经是物理地址了,就是一个线性偏移 的操作实现虚拟地址和物理地址的映射.
如果不需要访问物理设备,现在就可以完成了.
分页阶段2-重建映射 重映射的时候干脆在虚拟地址空间里把sbi去掉,因为不应该继续访问sbi了.
不同的数据段的权限不一样,比如READ,WRITE,EXECUTE不一样.比如代码段就只能读和运行不能写.在重建的时候就不需要给它这些权限.
这样设备的地址空间也可以被映射进来,权限粒度也更细.
这里似乎仍然是线性映射 .
多任务 需求:启用多任务,开一个子任务,让子任务替主任务完成一些具体工作,然后回到主任务.
并发 是多个任务同时在等待使用CPU而不是同时运行.并行 是真的需要同时运行.
调度的一个很好的描述:一个是保存现场 ,一个是任务无感知 .
实验多任务 make run A=tour/u_4_0
任务代码解析:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 #![cfg_attr(feature = "axstd" , no_std)] #![cfg_attr(feature = "axstd" , no_main)] #[macro_use] #[cfg(feature = "axstd" )] extern crate axstd as std;use core::{mem, str };use std::thread;use std::os::arceos::modules::axhal::mem::phys_to_virt;const PFLASH_START: usize = 0x2200_0000 ;#[cfg_attr(feature = "axstd" , no_mangle)] fn main println! ("Multi-task is starting ..." ); let worker = thread::spawn(move || { println! ("Spawned-thread ..." ); let va = phys_to_virt(PFLASH_START.into()).as_usize(); let ptr = va as *const u32 ; let magic = unsafe { mem::transmute::<u32 , [u8 ; 4 ]>(*ptr) }; if let Ok (s) = str ::from_utf8(&magic) { println! ("Got pflash magic: {s}" ); 0 } else { -1 } }); let ret = worker.join(); assert_eq! (ret, Ok (0 )); println! ("Multi-task OK!" ); }
和上一节的内容一样,同样是访问了我们预导入的pflash.img的前几个字符pfld.
只不过用了spawn的方法生成,并且用join的方法等待.
任务的数据结构
有一个关键点在于task_ext,是任务的拓展属性,是面向宏内核 和Hypervisor 的关键.
通用调度框架
分层,并且实现同样的接口,这样就可以自己决定是什么样的调度机制.
系统默认内置任务
GC: 除main之外的任务(线程)退出后，由gc负责回收清理。
IDLE: 当其它所有任务都阻塞时，执行它。对某些arch，wait_for_irqs对应非忙等指令.比如等待中断什么的,而不是忙等,如果发生新的”event“(自己取的名)那么就会马上响应.
MsgQueue 本节目标：
任务的切换机制，协作式调度算法
同步的方式，Mutex的机制
运行实验 执行make run A=tour/u_5_0:
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 160 161 162 163 164 165 166 167 168 169 170 171 172 173 174 175 176 177 178 179 180 181 182 183 184 185 186 187 188 189 190 191 192 193 194 195 196 197 198 199 200 201 202 203 204 205 206 207 208 209 210 211 212 213 214 215 216 217 218 219 220 221 222 223 224 225 226 227 228 229 230 231 232 233 234 235 236 237 238 239 240 241 242 243 244 245 246 247 248 249 250 251 252 253 254 255 256 OpenSBI v0.9 ____ _____ ____ _____ / __ \ / ____| _ \_ _| | | | |_ __ ___ _ __ | (___ | |_) || | | | | | '_ \ / _ \ '_ \ \___ \| _ < | | | |__| | |_) | __/ | | |____) | |_) || |_ \____/| .__/ \___|_| |_|_____/|____/_____| | | |_| Platform Name : riscv-virtio,qemu Platform Features : timer,mfdeleg Platform HART Count : 1 Firmware Base : 0x80000000 Firmware Size : 100 KB Runtime SBI Version : 0.2 Domain0 Name : root Domain0 Boot HART : 0 Domain0 HARTs : 0* Domain0 Region00 : 0x0000000080000000-0x000000008001ffff () Domain0 Region01 : 0x0000000000000000-0xffffffffffffffff (R,W,X) Domain0 Next Address : 0x0000000080200000 Domain0 Next Arg1 : 0x0000000087000000 Domain0 Next Mode : S-mode Domain0 SysReset : yes Boot HART ID : 0 Boot HART Domain : root Boot HART ISA : rv64imafdcsu Boot HART Features : scounteren,mcounteren,time Boot HART PMP Count : 16 Boot HART PMP Granularity : 4 Boot HART PMP Address Bits: 54 Boot HART MHPM Count : 0 Boot HART MHPM Count : 0 Boot HART MIDELEG : 0x0000000000000222 Boot HART MEDELEG : 0x000000000000b109 d8888 .d88888b. .d8888b. d88888 d88P" "Y88b d88P Y88b d88P888 888 888 Y88b. d88P 888 888d888 .d8888b .d88b. 888 888 "Y888b. d88P 888 888P" d88P" d8P Y8b 888 888 "Y88b. d88P 888 888 888 88888888 888 888 "888 d8888888888 888 Y88b. Y8b. Y88b. .d88P Y88b d88P d88P 888 888 "Y8888P "Y8888 "Y88888P" "Y8888P" arch = riscv64 platform = riscv64-qemu-virt target = riscv64gc-unknown-none-elf smp = 1 build_mode = release log_level = warn Multi-task is starting ... Wait for workers to exit ... worker1 ... worker1 [0] worker2 ... worker2 [0] worker2: nothing to do! worker1 [1] worker2 [1] worker2: nothing to do! worker1 [2] worker2 [2] worker2: nothing to do! worker1 [3] worker2 [3] worker2: nothing to do! worker1 [4] worker2 [4] worker2: nothing to do! worker1 [5] worker2 [5] worker2: nothing to do! worker1 [6] worker2 [6] worker2: nothing to do! worker1 [7] worker2 [7] worker2: nothing to do! worker1 [8] worker2 [8] worker2: nothing to do! worker1 [9] worker2 [9] worker2: nothing to do! worker1 [10] worker2 [10] worker2: nothing to do! worker1 [11] worker2 [11] worker2: nothing to do! worker1 [12] worker2 [12] worker2: nothing to do! worker1 [13] worker2 [13] worker2: nothing to do! worker1 [14] worker2 [14] worker2: nothing to do! worker1 [15] worker2 [15] worker2: nothing to do! worker1 [16] worker2 [16] worker2: nothing to do! worker1 [17] worker2 [17] worker2: nothing to do! worker1 [18] worker2 [18] worker2: nothing to do! worker1 [19] worker2 [19] worker2: nothing to do! worker1 [20] worker2 [20] worker2: nothing to do! worker1 [21] worker2 [21] worker2: nothing to do! worker1 [22] worker2 [22] worker2: nothing to do! worker1 [23] worker2 [23] worker2: nothing to do! worker1 [24] worker2 [24] worker2: nothing to do! worker1 [25] worker2 [25] worker2: nothing to do! worker1 [26] worker2 [26] worker2: nothing to do! worker1 [27] worker2 [27] worker2: nothing to do! worker1 [28] worker2 [28] worker2: nothing to do! worker1 [29] worker2 [29] worker2: nothing to do! worker1 [30] worker2 [30] worker2: nothing to do! worker1 [31] worker2 [31] worker2: nothing to do! worker1 [32] worker2 [32] worker2: nothing to do! worker1 [33] worker2 [33] worker2: nothing to do! worker1 [34] worker2 [34] worker2: nothing to do! worker1 [35] worker2 [35] worker2: nothing to do! worker1 [36] worker2 [36] worker2: nothing to do! worker1 [37] worker2 [37] worker2: nothing to do! worker1 [38] worker2 [38] worker2: nothing to do! worker1 [39] worker2 [39] worker2: nothing to do! worker1 [40] worker2 [40] worker2: nothing to do! worker1 [41] worker2 [41] worker2: nothing to do! worker1 [42] worker2 [42] worker2: nothing to do! worker1 [43] worker2 [43] worker2: nothing to do! worker1 [44] worker2 [44] worker2: nothing to do! worker1 [45] worker2 [45] worker2: nothing to do! worker1 [46] worker2 [46] worker2: nothing to do! worker1 [47] worker2 [47] worker2: nothing to do! worker1 [48] worker2 [48] worker2: nothing to do! worker1 [49] worker2 [49] worker2: nothing to do! worker1 [50] worker2 [50] worker2: nothing to do! worker1 [51] worker2 [51] worker2: nothing to do! worker1 [52] worker2 [52] worker2: nothing to do! worker1 [53] worker2 [53] worker2: nothing to do! worker1 [54] worker2 [54] worker2: nothing to do! worker1 [55] worker2 [55] worker2: nothing to do! worker1 [56] worker2 [56] worker2: nothing to do! worker1 [57] worker2 [57] worker2: nothing to do! worker1 [58] worker2 [58] worker2: nothing to do! worker1 [59] worker2 [59] worker2: nothing to do! worker1 [60] worker2 [60] worker2: nothing to do! worker1 [61] worker2 [61] worker2: nothing to do! worker1 [62] worker2 [62] worker2: nothing to do! worker1 [63] worker2 [63] worker2: nothing to do! worker1 [64] worker2 [64] worker2 ok! worker1 ok! Multi-task OK!
分析代码,worker1是尝试获取Arc中的这个双端队列 ,然后尝试在队列的最后放东西.
由于是协作式调度,worker1每次放入的之后都会yield,因此worker2就会接手,然后尝试把队列里所有的内容 都打出来,如果队列为空就报告worker2: nothing to do!,然后再由worker1接手CPU.
协作式调度 与rCore不同,现在使用的是List而不是一个数组,原理上就不设置任务的个数了.
互斥锁和自旋锁 自旋锁可能是我们脑子中的那个锁,每次访问资源需要访问这个锁,如果没办法访问那你这个任务要处理这种情况.
互斥锁则是自己加了一个等待队列,如果有任务在等待这个资源,那么这个任务被加入等待队列之后不会参与调度 ,这样就节省了很多任务切换时的资源.
bump内存分配算法 #TODO
挑战性作业 initialize global allocator at: [0xffffffc08026f000, 0xffffffc088000000)
5376*2
align是8的是有关于Vec的内存的分配
131,665,920
1048576
524288+8000
#TODO
