The Design and Implementation of the Anykernel and Rump Kernels

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220 It needs to be stressed that Table 4.3 only measures the amount of memory used by the virtualized NetBSD instance. The true cost is the amount of memory used on the system hosting the virtualized instance. This cost includes the virtualization container itself. The memory consumption, ignoring disk cache, for the second qemu -n 24 instance for NetBSD 5.99.48 on the host is 38.2MB — measuring the second instance avoids one-off costs, which are not relevant when talking about scaling capability. The difference between what the guest uses and what the host uses in this case is an additional 14.2MB in total memory consumption. When compared to the memory usage of 38.2MB for a virtual QEMU instance, a rump kernel’s default consumption is smaller by a factor of more than 20. This difference exists because a rump kernel does not need to duplicate features which it borrows from the host, and due to its flexible configurability, only the truly necessary set of components is required in the guest. 4.6.2 Bootstrap Time Startup time is important when the rump kernel is frequently bootstrapped and “thrown away”. This transitory execution happens for example with utilities and in test runs. It is also an enjoyment factor with interactive tasks, such as development work with a frequent iteration. As we mentioned in Section 2.1, delays of over 100ms are perceivable to humans [78]. We measured the bootstrap times of a full NetBSD system for two setups, one on hardware and one in a QEMU guest. While bootstrap times can at least to some degree be optimized by customization, the figures in Table 4.4 give us an indication of how long it takes to boot NetBSD. To put the figures into use case context, let us think about the testing setup we mentioned in Section 4.5.3. The test suite boots 911 rump kernels and an entire run takes 56 minutes. Extrapolating from Table 4.4,
221 platform version kernel boot login prompt hardware NetBSD 5.1 8s 22s QEMU NetBSD 5.99.48 14s 28s Table 4.4: Bootstrap times for standard NetBSD installations. 12 bootstrap time (ms) 10 8 6 4 2 0 kern dev net vfs Figure 4.11: Time required to bootstrap one rump kernel. The time varies from configuration to configuration because of the the initialization code that must be run during bootstrap. bootstrapping 911 instances of NetBSD in QEMU takes 7.1 hours, which is seven and a half times as long as running the entire test suite took using rump kernels. The bootstrap times for various rump kernel faction configurations are presented in Figure 4.11. In general, it can be said that a rump kernel bootstraps itself in a matter of milliseconds, i.e. a rump kernel outperforms a full system by a factor of 1000 with this metric.
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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
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55 We must solve the lack of a rump
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57 2.3.1 Kernel threads Up until no
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59 void * pool_cache_get_paddr(pool
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61 2.3.4 An Example We present an e
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63 Figure 2.6: Prov
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65 The straightforward use of exist
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68 We identified three obstacles fo
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70 for loadable kernel modules (dis
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72 e.g. the routine for mapping a p
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74 3.2.1 C Symbol Namespaces In the
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76 the double underscore namespace
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78 since the representation might n
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80 The following rumpuser interface
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82 The entry point rump_schedule()
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84 3.3.1 CPU Scheduling Recall from
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86 The fastpath is taken in cases w
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88 Releasing a CPU requires the fol
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90 10 8 seconds 6 4 2 0 1CPU 2CPU n
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92 Hardware interrupt handlers are
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94 Due to the design choice that a
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96 in. Therefore, we should critica
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98 Pager window create+access time
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100 A rump kernel can be configured
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102 Since all pages managed by the
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104 not in control of thread schedu
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106 synchronization part of the alg
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108 /* * Run a cross call to cycle
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110 kernel needs to do is make sure
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112 The kernel with uniprocessor lo
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114 the header file while open() c
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116 The same wrapper works both for
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118 5. Some calling conventions (e.
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120 int rump_pub_lwproc_rfork(int a
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122 By convention, file system devi
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124 ule directory tree from /stand
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126 After these steps have been per
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128 Host Dynamic Linker Using the h
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130 for (i = 0; i < SYS_NSYSENT; i+
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132 into a rump kernel and the driv
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134 sys/arch/x86/include/cpu.h: #de
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136 3.8.4 Rump Component Init Routi
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138 RUMP_COMPONENT(RUMP_COMPONENT_N
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140 We have three distinct cases we
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142 # ifconfig tap0 create # ifconf
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144 Unprivileged use of host’s ne
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146 DOMAIN_DEFINE(sockindomain); co
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148 issue another write before the
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150 using an interface called USBDI
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152 The kernel device configuration
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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
Page 172 and 173: 170 Host syscall rump syscall 1. op
Page 174 and 175: 172 A client’s initial connection
Page 176 and 177: 174 their system calls to a rump ke
Page 178 and 179: 176 stdin/stdout, the new file desc
Page 180 and 181: 178 Supporting fork() Recall, the f
Page 182 and 183: 180 As with fork, most of the kerne
Page 184 and 185: 182 Anecdotal analysis For several
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Page 188 and 189: 186 SLOC 8000 7000 6000 5000 4000 3
Page 190 and 191: 188 Total commits to the kernel 9,6
Page 192 and 193: 190 120 build time (minutes) 100 80
Page 194 and 195: 192 4.2.2 makefs For a source tree
Page 196 and 197: 194 not include later debugging [76
Page 198 and 199: 196 the necessary tools such as mak
Page 200 and 201: 198 proach of supplying alternate c
Page 202 and 203: 200 are not out-of-the-box compatib
Page 204 and 205: 202 golem> mount -t msdos -o rump /
Page 206 and 207: 204 Full OS By a full OS we mean a
Page 208 and 209: 206 • Rapid prototyping: One of t
Page 210 and 211: 208 4.5.3 Testing: Case Studies We
Page 212 and 213: 210 static void scsitest_request(st
Page 214 and 215: 212 waits for the timeout and check
Page 216 and 217: 214 • We noticed that even in sup
Page 218 and 219: 216 which were discovered during wr
Page 220 and 221: 218 version swap no swap NetBSD 5.1
Page 224 and 225: 222 Network clusters Bootstrapping
Page 226 and 227: 224 8 7 Standard components Self-co
Page 228 and 229: 226 Rump kernel calls, as expected,
Page 230 and 231: 228 Traditional FFS We measure the
Page 232 and 233: 230 80 70 60 seconds 50 40 30 20 10
Page 234 and 235: 232 The results are presented in Fi
Page 236 and 237: 234 behavior is required by the act
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Page 240 and 241: 238 Rialto [29] is an operating sys
Page 242 and 243: 240 One argument for partitioned op
Page 244 and 245: 242 View OS The View OS [37] approa
Page 246 and 247: 244 OSKit Instead of making system
Page 248 and 249: 246 discussing the type incompatibi
Page 250 and 251: 248 difference to the abovementione
Page 252 and 253: 250 At runtime, a rump kernel can a
Page 254 and 255: 252 For testing and development we
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Page 258 and 259: 256 Art of Virtualization. In: Proc
Page 260 and 261: 258 [30] Adam Dunkels. 2001. Design
Page 262 and 263: 260 [47] Galen C. Hunt and James R.
Page 264 and 265: 262 [67] Steven McCanne and Van Jac
Page 266 and 267: 264 [87] NetBSD Project. URL http:/
Page 268 and 269: 266 of the 6th Workshop on Programm
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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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