The Design and Implementation of the Anykernel and Rump Kernels

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146 DOMAIN_DEFINE(sockindomain); const struct protosw sockinsw[] = { { .pr_type = SOCK_DGRAM, /* UDP */ .pr_domain = &sockindomain, .pr_protocol = IPPROTO_UDP, .pr_flags = PR_ATOMIC | PR_ADDR, .pr_usrreq = sockin_usrreq, .pr_ctloutput = sockin_ctloutput, },{ .pr_type = SOCK_STREAM, /* TCP */ .pr_domain = &sockindomain, .pr_protocol = IPPROTO_TCP, .pr_flags = PR_CONNREQUIRED | PR_WANTRCVD | PR_LISTEN | PR_ABRTACPTDIS, .pr_usrreq = sockin_usrreq, .pr_ctloutput = sockin_ctloutput, }}; struct domain sockindomain = { .dom_family = PF_INET, .dom_name = "socket_inet", .dom_init = sockin_init, .dom_externalize = NULL, .dom_dispose = NULL, .dom_protosw = sockinsw, .dom_protoswNPROTOSW = &sockinsw[__arraycount(sockinsw)], .dom_rtattach = rn_inithead, .dom_rtoffset = 32, .dom_maxrtkey = sizeof(struct sockaddr_in), .dom_ifattach = NULL, .dom_ifdetach = NULL, .dom_ifqueues = { NULL }, .dom_link = { NULL }, .dom_mowner = MOWNER_INIT("",""), .dom_rtcache = { NULL }, .dom_sockaddr_cmp = NULL }; Figure 3.23: sockin attachment. Networking domains in NetBSD are attached by specifying a struct domain. Notably, the sockin family attaches a PF_INET type family since it aims to provide an alternative implementation for inet sockets.
147 the object the data belongs to (e.g. vm page) is held locked. Once the request is complete, the driver signals the kernel that the request has been completed. In case the caller waits for the request to complete, the request is said to be synchronous, otherwise asynchronous. There are two ways to provide a disk backend: buffered and unbuffered. A buffered backend stores writes to a buffer and flushes them to the backing storage later. An unbuffered backend will write to storage immediately. Examples of these backend types are a regular file and a character special device, respectively. There are three approaches to implementing the block driver using standard userspace interfaces. • Use read() and write() in caller context: this is the simplest method. However, this method effectively makes all requests synchronous. Additionally, this method blocks other read operations when read-ahead is being performed. • Asynchronous read/write: in this model the request is handed off to an I/O thread. When the request has been completed, the I/O thread signals completion. A buffered backend must flush synchronously executed writes. The only standard interface available for flushing is fsync(). However, it will flush all buffered data before returning, including previous asynchronous writes. Nonstandard ranged interfaces such as fsync_range() exist, but they usually flush at least some file metadata in addition the actual data causing extra unnecessary I/O. A userlevel write to an unbuffered backend goes directly to storage. The system call will return only after the write has been completed. No flushing is required, but since userlevel I/O is serialized on Unix, it is not possible to
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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
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 108 and 109: 106 synchronization part of the alg
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 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
Page 158 and 159: 156 USB Host Controller Hub0 (root)
Page 160 and 161: 158 Figure 3.30: File s
Page 162 and 163: 160 in-kernel mount: /dev/sd0e /m/u
Page 164 and 165: 162 structure being created by rump
Page 166 and 167: 164 3.12.1 Client-Kernel Locators B
Page 168 and 169: 166 A tmpfs server listening on INA
Page 170 and 171: 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
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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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The Design and Implementation of the Anykernel and Rump Kernels

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