The Design and Implementation of the Anykernel and Rump Kernels

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106 synchronization part of the algorithm, and then explain how it works in a rump kernel. Four cases must be handled: 1. execution of a system call which is loaded and functional (fast path) 2. loading a system call 3. attempting to execute an absent system call 4. unloading a system call 1: Regular Execution Executing a system call is considered a read side lock. The essential steps are: 1. Set currently executing system call in curlwp->l_sysent. This step is executed lockless and without memory barriers. 2. Execute system call. 3. Clear curlwp->l_sysent. 2: Loading a System Call Modifying the syscall vector is serialized using a lock. Since modification happens seldom compared to syscall execution, this is not a performance issue. 1. Take the kernel configuration lock.
107 2. Check that the system call handler was not loading before we got the lock. If it was, another thread raced us into loading the call and we abort. 3. Patch the new value to the system call vector. 4. Release the configuration lock. 3: Absent System Call NetBSD supports autoloading absent system calls. This means that when a process makes a system call that is not supported, loading a handler may be automatically attempted. If loading a handler is successful, the system call may be able to complete without returning an error to the caller. System calls which may be loaded at runtime are set to the following stub in the syscall vector: 1. Take the kernel configuration lock. Locking is not a performance problem, since any unloaded system calls will not be frequently used by applications, and therefore will not affect system performance. 2. Check that the system call handler was not loading before we got the lock. If it was, another thread raced us into loading the call and we restart handling. Otherwise, we attempt to load the system call and patch the syscall vector. 3. Release the configuration lock. 4. If the system call handler was loaded (by us or another thread), restart system call handling. Otherwise, return ENOSYS and, due to Unix semantics, post SIGSYS.
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Department of Computer Science and
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9 Preface Meet the new boss Same as
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11 Then there is my dear Xi, who, s
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14 2.3.3 InterruptsandPreemption...
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16 4.1.1 Implementation Effort ....
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18 Appendix C Patches to the 5.99.4
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20 ISA LGPL LRU LWP MD MI MMU NIC O
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23 List of Figures 2.1 Rumpkernelhi
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25 4.14 Time to execute 5M system c
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29 1 Introduction In its classic ro
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31 and application-level drivers. T
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33 We define an anykernel to be an
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35 Our implementation supports rump
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37 The project was done in small in
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39 2 The Anykernel and Rump Kernels
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41 building on top of the entities
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43 Drivers in a rump kernel remain
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45 Figure 2.1: Rump k
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47 in Section 3.2.3. Whenever discu
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49 int rumpns_bpfopen(dev_t, int, i
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51 Figure 2.4:
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53 while the application logic stil
Page 57 and 58: 55 We must solve the lack of a rump
Page 59 and 60: 57 2.3.1 Kernel threads Up until no
Page 61 and 62: 59 void * pool_cache_get_paddr(pool
Page 63 and 64: 61 2.3.4 An Example We present an e
Page 65 and 66: 63 Figure 2.6: Prov
Page 67: 65 The straightforward use of exist
Page 70 and 71: 68 We identified three obstacles fo
Page 72 and 73: 70 for loadable kernel modules (dis
Page 74 and 75: 72 e.g. the routine for mapping a p
Page 76 and 77: 74 3.2.1 C Symbol Namespaces In the
Page 78 and 79: 76 the double underscore namespace
Page 80 and 81: 78 since the representation might n
Page 82 and 83: 80 The following rumpuser interface
Page 84 and 85: 82 The entry point rump_schedule()
Page 86 and 87: 84 3.3.1 CPU Scheduling Recall from
Page 88 and 89: 86 The fastpath is taken in cases w
Page 90 and 91: 88 Releasing a CPU requires the fol
Page 92 and 93: 90 10 8 seconds 6 4 2 0 1CPU 2CPU n
Page 94 and 95: 92 Hardware interrupt handlers are
Page 96 and 97: 94 Due to the design choice that a
Page 98 and 99: 96 in. Therefore, we should critica
Page 100 and 101: 98 Pager window create+access time
Page 102 and 103: 100 A rump kernel can be configured
Page 104 and 105: 102 Since all pages managed by the
Page 106 and 107: 104 not in control of thread schedu
Page 110 and 111: 108 /* * Run a cross call to cycle
Page 112 and 113: 110 kernel needs to do is make sure
Page 114 and 115: 112 The kernel with uniprocessor lo
Page 116 and 117: 114 the header file while open() c
Page 118 and 119: 116 The same wrapper works both for
Page 120 and 121: 118 5. Some calling conventions (e.
Page 122 and 123: 120 int rump_pub_lwproc_rfork(int a
Page 124 and 125: 122 By convention, file system devi
Page 126 and 127: 124 ule directory tree from /stand
Page 128 and 129: 126 After these steps have been per
Page 130 and 131: 128 Host Dynamic Linker Using the h
Page 132 and 133: 130 for (i = 0; i < SYS_NSYSENT; i+
Page 134 and 135: 132 into a rump kernel and the driv
Page 136 and 137: 134 sys/arch/x86/include/cpu.h: #de
Page 138 and 139: 136 3.8.4 Rump Component Init Routi
Page 140 and 141: 138 RUMP_COMPONENT(RUMP_COMPONENT_N
Page 142 and 143: 140 We have three distinct cases we
Page 144 and 145: 142 # ifconfig tap0 create # ifconf
Page 146 and 147: 144 Unprivileged use of host’s ne
Page 148 and 149: 146 DOMAIN_DEFINE(sockindomain); co
Page 150 and 151: 148 issue another write before the
Page 152 and 153: 150 using an interface called USBDI
Page 154 and 155: 152 The kernel device configuration
Page 156 and 157: 154 # $NetBSD: UMASS.ioconf,v 1.4 2
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156 USB Host Controller Hub0 (root)
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158 Figure 3.30: File s
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160 in-kernel mount: /dev/sd0e /m/u
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162 structure being created by rump
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164 3.12.1 Client-Kernel Locators B
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166 A tmpfs server listening on INA
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168 Request Arguments Response Desc
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170 Host syscall rump syscall 1. op
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172 A client’s initial connection
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174 their system calls to a rump ke
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176 stdin/stdout, the new file desc
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178 Supporting fork() Recall, the f
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180 As with fork, most of the kerne
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182 Anecdotal analysis For several
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184
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186 SLOC 8000 7000 6000 5000 4000 3
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188 Total commits to the kernel 9,6
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190 120 build time (minutes) 100 80
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192 4.2.2 makefs For a source tree
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194 not include later debugging [76
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196 the necessary tools such as mak
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198 proach of supplying alternate c
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200 are not out-of-the-box compatib
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202 golem> mount -t msdos -o rump /
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204 Full OS By a full OS we mean a
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206 • Rapid prototyping: One of t
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208 4.5.3 Testing: Case Studies We
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210 static void scsitest_request(st
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212 waits for the timeout and check
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214 • We noticed that even in sup
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216 which were discovered during wr
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218 version swap no swap NetBSD 5.1
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220 It needs to be stressed that Ta
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222 Network clusters Bootstrapping
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224 8 7 Standard components Self-co
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226 Rump kernel calls, as expected,
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228 Traditional FFS We measure the
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230 80 70 60 seconds 50 40 30 20 10
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232 The results are presented in Fi
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234 behavior is required by the act
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236
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238 Rialto [29] is an operating sys
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240 One argument for partitioned op
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242 View OS The View OS [37] approa
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244 OSKit Instead of making system
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246 discussing the type incompatibi
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248 difference to the abovementione
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250 At runtime, a rump kernel can a
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252 For testing and development we
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254
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256 Art of Virtualization. In: Proc
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258 [30] Adam Dunkels. 2001. Design
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260 [47] Galen C. Hunt and James R.
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262 [67] Steven McCanne and Van Jac
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264 [87] NetBSD Project. URL http:/
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266 of the 6th Workshop on Programm
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268
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A-2 RUMP.DHCPCLIENT(1) NetBSD Gener
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A-4 RUMP.HALT(1) NetBSD General Com
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A-6 RUMP_SERVER(1) NetBSD General C
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A-8 RUMP_SERVER(1) NetBSD General C
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A-10 SHMIF_DUMPBUS(1) NetBSD Genera
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A-12 P2K(3) NetBSD Library Function
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A-14 P2K(3) NetBSD Library Function
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A-16 RUMP(3) NetBSD Library Functio
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A-18 RUMP(3) NetBSD Library Functio
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A-20 RUMP_ETFS(3) NetBSD Library Fu
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A-22 RUMP_ETFS(3) NetBSD Library Fu
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A-24 RUMP_LWPROC(3) NetBSD Library
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A-26 RUMP_LWPROC(3) NetBSD Library
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A-28 RUMPCLIENT(3) NetBSD Library F
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A-30 RUMPCLIENT(3) NetBSD Library F
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A-32 RUMPHIJACK(3) NetBSD Library F
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A-38 UKFS(3) NetBSD Library Functio
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A-48 SHMIF(4) NetBSD Kernel Interfa
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A-50 RUMP_SP(7) NetBSD Miscellaneou
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A-52 RUMP_SP(7) NetBSD Miscellaneou
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B-2 TCP connections use standard TC
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B-4 rump clients. This means that j
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B-6 ponents. That can be done simpl
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B-8 Our goal is to add another part
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B-10 golem> export RUMP_SERVER=unix
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B-12 golem> rump.dd if=/dev/rcgd0d
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B-14 demogorgon# cgdconfig cgd0 /de
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B-16 rump_server -lrumpnet -lrumpne
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B-18 golem> rump.ifconfig virt0 cre
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B-20 Congratulations, that’s it.
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B-22 purely in userspace, it does n
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B-24 We then proceed to create a mo
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B-26 Then, the only thing left is t
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B-28 -d key=/dk,hostpath=${NFSX}/ff
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B-30 configuration. golem> sh rumpn
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B-32
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C-2 This is a quick fix for making
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C-4 This fixes the conditionally co
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Aalto-DD 171/2012 9HSTFMG*aejbgi+ I
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