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1 | Read the F-ing Papers! |
2 | ||
3 | ||
4 | This document describes RCU-related publications, and is followed by | |
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5 | the corresponding bibtex entries. A number of the publications may |
6 | be found at http://www.rdrop.com/users/paulmck/RCU/. | |
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7 | |
8 | The first thing resembling RCU was published in 1980, when Kung and Lehman | |
9 | [Kung80] recommended use of a garbage collector to defer destruction | |
10 | of nodes in a parallel binary search tree in order to simplify its | |
11 | implementation. This works well in environments that have garbage | |
12 | collectors, but current production garbage collectors incur significant | |
13 | read-side overhead. | |
14 | ||
15 | In 1982, Manber and Ladner [Manber82,Manber84] recommended deferring | |
16 | destruction until all threads running at that time have terminated, again | |
17 | for a parallel binary search tree. This approach works well in systems | |
18 | with short-lived threads, such as the K42 research operating system. | |
19 | However, Linux has long-lived tasks, so more is needed. | |
20 | ||
21 | In 1986, Hennessy, Osisek, and Seigh [Hennessy89] introduced passive | |
22 | serialization, which is an RCU-like mechanism that relies on the presence | |
23 | of "quiescent states" in the VM/XA hypervisor that are guaranteed not | |
24 | to be referencing the data structure. However, this mechanism was not | |
25 | optimized for modern computer systems, which is not surprising given | |
26 | that these overheads were not so expensive in the mid-80s. Nonetheless, | |
27 | passive serialization appears to be the first deferred-destruction | |
28 | mechanism to be used in production. Furthermore, the relevant patent has | |
29 | lapsed, so this approach may be used in non-GPL software, if desired. | |
30 | (In contrast, use of RCU is permitted only in software licensed under | |
31 | GPL. Sorry!!!) | |
32 | ||
33 | In 1990, Pugh [Pugh90] noted that explicitly tracking which threads | |
34 | were reading a given data structure permitted deferred free to operate | |
35 | in the presence of non-terminating threads. However, this explicit | |
36 | tracking imposes significant read-side overhead, which is undesirable | |
37 | in read-mostly situations. This algorithm does take pains to avoid | |
38 | write-side contention and parallelize the other write-side overheads by | |
39 | providing a fine-grained locking design, however, it would be interesting | |
40 | to see how much of the performance advantage reported in 1990 remains | |
41 | in 2004. | |
42 | ||
43 | At about this same time, Adams [Adams91] described ``chaotic relaxation'', | |
44 | where the normal barriers between successive iterations of convergent | |
45 | numerical algorithms are relaxed, so that iteration $n$ might use | |
46 | data from iteration $n-1$ or even $n-2$. This introduces error, | |
47 | which typically slows convergence and thus increases the number of | |
48 | iterations required. However, this increase is sometimes more than made | |
49 | up for by a reduction in the number of expensive barrier operations, | |
50 | which are otherwise required to synchronize the threads at the end | |
51 | of each iteration. Unfortunately, chaotic relaxation requires highly | |
52 | structured data, such as the matrices used in scientific programs, and | |
53 | is thus inapplicable to most data structures in operating-system kernels. | |
54 | ||
55 | In 1993, Jacobson [Jacobson93] verbally described what is perhaps the | |
56 | simplest deferred-free technique: simply waiting a fixed amount of time | |
57 | before freeing blocks awaiting deferred free. Jacobson did not describe | |
58 | any write-side changes he might have made in this work using SGI's Irix | |
59 | kernel. Aju John published a similar technique in 1995 [AjuJohn95]. | |
60 | This works well if there is a well-defined upper bound on the length of | |
61 | time that reading threads can hold references, as there might well be in | |
62 | hard real-time systems. However, if this time is exceeded, perhaps due | |
63 | to preemption, excessive interrupts, or larger-than-anticipated load, | |
64 | memory corruption can ensue, with no reasonable means of diagnosis. | |
65 | Jacobson's technique is therefore inappropriate for use in production | |
66 | operating-system kernels, except when such kernels can provide hard | |
67 | real-time response guarantees for all operations. | |
68 | ||
69 | Also in 1995, Pu et al. [Pu95a] applied a technique similar to that of Pugh's | |
70 | read-side-tracking to permit replugging of algorithms within a commercial | |
71 | Unix operating system. However, this replugging permitted only a single | |
72 | reader at a time. The following year, this same group of researchers | |
73 | extended their technique to allow for multiple readers [Cowan96a]. | |
74 | Their approach requires memory barriers (and thus pipeline stalls), | |
75 | but reduces memory latency, contention, and locking overheads. | |
76 | ||
77 | 1995 also saw the first publication of DYNIX/ptx's RCU mechanism | |
78 | [Slingwine95], which was optimized for modern CPU architectures, | |
79 | and was successfully applied to a number of situations within the | |
80 | DYNIX/ptx kernel. The corresponding conference paper appeared in 1998 | |
81 | [McKenney98]. | |
82 | ||
83 | In 1999, the Tornado and K42 groups described their "generations" | |
84 | mechanism, which quite similar to RCU [Gamsa99]. These operating systems | |
85 | made pervasive use of RCU in place of "existence locks", which greatly | |
86 | simplifies locking hierarchies. | |
87 | ||
88 | 2001 saw the first RCU presentation involving Linux [McKenney01a] | |
89 | at OLS. The resulting abundance of RCU patches was presented the | |
90 | following year [McKenney02a], and use of RCU in dcache was first | |
91 | described that same year [Linder02a]. | |
92 | ||
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93 | Also in 2002, Michael [Michael02b,Michael02a] presented "hazard-pointer" |
94 | techniques that defer the destruction of data structures to simplify | |
95 | non-blocking synchronization (wait-free synchronization, lock-free | |
96 | synchronization, and obstruction-free synchronization are all examples of | |
97 | non-blocking synchronization). In particular, this technique eliminates | |
98 | locking, reduces contention, reduces memory latency for readers, and | |
99 | parallelizes pipeline stalls and memory latency for writers. However, | |
100 | these techniques still impose significant read-side overhead in the | |
101 | form of memory barriers. Researchers at Sun worked along similar lines | |
102 | in the same timeframe [HerlihyLM02,HerlihyLMS03]. These techniques | |
103 | can be thought of as inside-out reference counts, where the count is | |
104 | represented by the number of hazard pointers referencing a given data | |
105 | structure (rather than the more conventional counter field within the | |
106 | data structure itself). | |
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107 | |
108 | In 2003, the K42 group described how RCU could be used to create | |
109 | hot-pluggable implementations of operating-system functions. Later that | |
110 | year saw a paper describing an RCU implementation of System V IPC | |
111 | [Arcangeli03], and an introduction to RCU in Linux Journal [McKenney03a]. | |
112 | ||
113 | 2004 has seen a Linux-Journal article on use of RCU in dcache | |
114 | [McKenney04a], a performance comparison of locking to RCU on several | |
115 | different CPUs [McKenney04b], a dissertation describing use of RCU in a | |
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116 | number of operating-system kernels [PaulEdwardMcKenneyPhD], a paper |
117 | describing how to make RCU safe for soft-realtime applications [Sarma04c], | |
118 | and a paper describing SELinux performance with RCU [JamesMorris04b]. | |
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120 | 2005 has seen further adaptation of RCU to realtime use, permitting |
121 | preemption of RCU realtime critical sections [PaulMcKenney05a, | |
122 | PaulMcKenney05b]. | |
123 | ||
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124 | Bibtex Entries |
125 | ||
126 | @article{Kung80 | |
127 | ,author="H. T. Kung and Q. Lehman" | |
128 | ,title="Concurrent Maintenance of Binary Search Trees" | |
129 | ,Year="1980" | |
130 | ,Month="September" | |
131 | ,journal="ACM Transactions on Database Systems" | |
132 | ,volume="5" | |
133 | ,number="3" | |
134 | ,pages="354-382" | |
135 | } | |
136 | ||
137 | @techreport{Manber82 | |
138 | ,author="Udi Manber and Richard E. Ladner" | |
139 | ,title="Concurrency Control in a Dynamic Search Structure" | |
140 | ,institution="Department of Computer Science, University of Washington" | |
141 | ,address="Seattle, Washington" | |
142 | ,year="1982" | |
143 | ,number="82-01-01" | |
144 | ,month="January" | |
145 | ,pages="28" | |
146 | } | |
147 | ||
148 | @article{Manber84 | |
149 | ,author="Udi Manber and Richard E. Ladner" | |
150 | ,title="Concurrency Control in a Dynamic Search Structure" | |
151 | ,Year="1984" | |
152 | ,Month="September" | |
153 | ,journal="ACM Transactions on Database Systems" | |
154 | ,volume="9" | |
155 | ,number="3" | |
156 | ,pages="439-455" | |
157 | } | |
158 | ||
159 | @techreport{Hennessy89 | |
160 | ,author="James P. Hennessy and Damian L. Osisek and Joseph W. {Seigh II}" | |
161 | ,title="Passive Serialization in a Multitasking Environment" | |
162 | ,institution="US Patent and Trademark Office" | |
163 | ,address="Washington, DC" | |
164 | ,year="1989" | |
165 | ,number="US Patent 4,809,168 (lapsed)" | |
166 | ,month="February" | |
167 | ,pages="11" | |
168 | } | |
169 | ||
170 | @techreport{Pugh90 | |
171 | ,author="William Pugh" | |
172 | ,title="Concurrent Maintenance of Skip Lists" | |
173 | ,institution="Institute of Advanced Computer Science Studies, Department of Computer Science, University of Maryland" | |
174 | ,address="College Park, Maryland" | |
175 | ,year="1990" | |
176 | ,number="CS-TR-2222.1" | |
177 | ,month="June" | |
178 | } | |
179 | ||
180 | @Book{Adams91 | |
181 | ,Author="Gregory R. Adams" | |
182 | ,title="Concurrent Programming, Principles, and Practices" | |
183 | ,Publisher="Benjamin Cummins" | |
184 | ,Year="1991" | |
185 | } | |
186 | ||
187 | @unpublished{Jacobson93 | |
188 | ,author="Van Jacobson" | |
189 | ,title="Avoid Read-Side Locking Via Delayed Free" | |
190 | ,year="1993" | |
191 | ,month="September" | |
192 | ,note="Verbal discussion" | |
193 | } | |
194 | ||
195 | @Conference{AjuJohn95 | |
196 | ,Author="Aju John" | |
197 | ,Title="Dynamic vnodes -- Design and Implementation" | |
198 | ,Booktitle="{USENIX Winter 1995}" | |
199 | ,Publisher="USENIX Association" | |
200 | ,Month="January" | |
201 | ,Year="1995" | |
202 | ,pages="11-23" | |
203 | ,Address="New Orleans, LA" | |
204 | } | |
205 | ||
206 | @techreport{Slingwine95 | |
207 | ,author="John D. Slingwine and Paul E. McKenney" | |
208 | ,title="Apparatus and Method for Achieving Reduced Overhead Mutual | |
209 | Exclusion and Maintaining Coherency in a Multiprocessor System | |
210 | Utilizing Execution History and Thread Monitoring" | |
211 | ,institution="US Patent and Trademark Office" | |
212 | ,address="Washington, DC" | |
213 | ,year="1995" | |
214 | ,number="US Patent 5,442,758 (contributed under GPL)" | |
215 | ,month="August" | |
216 | } | |
217 | ||
218 | @techreport{Slingwine97 | |
219 | ,author="John D. Slingwine and Paul E. McKenney" | |
220 | ,title="Method for maintaining data coherency using thread | |
221 | activity summaries in a multicomputer system" | |
222 | ,institution="US Patent and Trademark Office" | |
223 | ,address="Washington, DC" | |
224 | ,year="1997" | |
225 | ,number="US Patent 5,608,893 (contributed under GPL)" | |
226 | ,month="March" | |
227 | } | |
228 | ||
229 | @techreport{Slingwine98 | |
230 | ,author="John D. Slingwine and Paul E. McKenney" | |
231 | ,title="Apparatus and method for achieving reduced overhead | |
232 | mutual exclusion and maintaining coherency in a multiprocessor | |
233 | system utilizing execution history and thread monitoring" | |
234 | ,institution="US Patent and Trademark Office" | |
235 | ,address="Washington, DC" | |
236 | ,year="1998" | |
237 | ,number="US Patent 5,727,209 (contributed under GPL)" | |
238 | ,month="March" | |
239 | } | |
240 | ||
241 | @Conference{McKenney98 | |
242 | ,Author="Paul E. McKenney and John D. Slingwine" | |
243 | ,Title="Read-Copy Update: Using Execution History to Solve Concurrency | |
244 | Problems" | |
245 | ,Booktitle="{Parallel and Distributed Computing and Systems}" | |
246 | ,Month="October" | |
247 | ,Year="1998" | |
248 | ,pages="509-518" | |
249 | ,Address="Las Vegas, NV" | |
250 | } | |
251 | ||
252 | @Conference{Gamsa99 | |
253 | ,Author="Ben Gamsa and Orran Krieger and Jonathan Appavoo and Michael Stumm" | |
254 | ,Title="Tornado: Maximizing Locality and Concurrency in a Shared Memory | |
255 | Multiprocessor Operating System" | |
256 | ,Booktitle="{Proceedings of the 3\textsuperscript{rd} Symposium on | |
257 | Operating System Design and Implementation}" | |
258 | ,Month="February" | |
259 | ,Year="1999" | |
260 | ,pages="87-100" | |
261 | ,Address="New Orleans, LA" | |
262 | } | |
263 | ||
264 | @techreport{Slingwine01 | |
265 | ,author="John D. Slingwine and Paul E. McKenney" | |
266 | ,title="Apparatus and method for achieving reduced overhead | |
267 | mutual exclusion and maintaining coherency in a multiprocessor | |
268 | system utilizing execution history and thread monitoring" | |
269 | ,institution="US Patent and Trademark Office" | |
270 | ,address="Washington, DC" | |
271 | ,year="2001" | |
272 | ,number="US Patent 5,219,690 (contributed under GPL)" | |
273 | ,month="April" | |
274 | } | |
275 | ||
276 | @Conference{McKenney01a | |
277 | ,Author="Paul E. McKenney and Jonathan Appavoo and Andi Kleen and | |
278 | Orran Krieger and Rusty Russell and Dipankar Sarma and Maneesh Soni" | |
279 | ,Title="Read-Copy Update" | |
280 | ,Booktitle="{Ottawa Linux Symposium}" | |
281 | ,Month="July" | |
282 | ,Year="2001" | |
283 | ,note="Available: | |
284 | \url{http://www.linuxsymposium.org/2001/abstracts/readcopy.php} | |
285 | \url{http://www.rdrop.com/users/paulmck/rclock/rclock_OLS.2001.05.01c.pdf} | |
286 | [Viewed June 23, 2004]" | |
287 | annotation=" | |
288 | Described RCU, and presented some patches implementing and using it in | |
289 | the Linux kernel. | |
290 | " | |
291 | } | |
292 | ||
293 | @Conference{Linder02a | |
294 | ,Author="Hanna Linder and Dipankar Sarma and Maneesh Soni" | |
295 | ,Title="Scalability of the Directory Entry Cache" | |
296 | ,Booktitle="{Ottawa Linux Symposium}" | |
297 | ,Month="June" | |
298 | ,Year="2002" | |
299 | ,pages="289-300" | |
300 | } | |
301 | ||
302 | @Conference{McKenney02a | |
303 | ,Author="Paul E. McKenney and Dipankar Sarma and | |
304 | Andrea Arcangeli and Andi Kleen and Orran Krieger and Rusty Russell" | |
305 | ,Title="Read-Copy Update" | |
306 | ,Booktitle="{Ottawa Linux Symposium}" | |
307 | ,Month="June" | |
308 | ,Year="2002" | |
309 | ,pages="338-367" | |
310 | ,note="Available: | |
311 | \url{http://www.linux.org.uk/~ajh/ols2002_proceedings.pdf.gz} | |
312 | [Viewed June 23, 2004]" | |
313 | } | |
314 | ||
315 | @article{Appavoo03a | |
316 | ,author="J. Appavoo and K. Hui and C. A. N. Soules and R. W. Wisniewski and | |
317 | D. M. {Da Silva} and O. Krieger and M. A. Auslander and D. J. Edelsohn and | |
318 | B. Gamsa and G. R. Ganger and P. McKenney and M. Ostrowski and | |
319 | B. Rosenburg and M. Stumm and J. Xenidis" | |
320 | ,title="Enabling Autonomic Behavior in Systems Software With Hot Swapping" | |
321 | ,Year="2003" | |
322 | ,Month="January" | |
323 | ,journal="IBM Systems Journal" | |
324 | ,volume="42" | |
325 | ,number="1" | |
326 | ,pages="60-76" | |
327 | } | |
328 | ||
329 | @Conference{Arcangeli03 | |
330 | ,Author="Andrea Arcangeli and Mingming Cao and Paul E. McKenney and | |
331 | Dipankar Sarma" | |
332 | ,Title="Using Read-Copy Update Techniques for {System V IPC} in the | |
333 | {Linux} 2.5 Kernel" | |
334 | ,Booktitle="Proceedings of the 2003 USENIX Annual Technical Conference | |
335 | (FREENIX Track)" | |
336 | ,Publisher="USENIX Association" | |
337 | ,year="2003" | |
338 | ,month="June" | |
339 | ,pages="297-310" | |
340 | } | |
341 | ||
342 | @article{McKenney03a | |
343 | ,author="Paul E. McKenney" | |
344 | ,title="Using {RCU} in the {Linux} 2.5 Kernel" | |
345 | ,Year="2003" | |
346 | ,Month="October" | |
347 | ,journal="Linux Journal" | |
348 | ,volume="1" | |
349 | ,number="114" | |
350 | ,pages="18-26" | |
351 | } | |
352 | ||
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353 | @techreport{Friedberg03a |
354 | ,author="Stuart A. Friedberg" | |
355 | ,title="Lock-Free Wild Card Search Data Structure and Method" | |
356 | ,institution="US Patent and Trademark Office" | |
357 | ,address="Washington, DC" | |
358 | ,year="2003" | |
359 | ,number="US Patent 6,662,184 (contributed under GPL)" | |
360 | ,month="December" | |
361 | ,pages="112" | |
362 | } | |
363 | ||
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364 | @article{McKenney04a |
365 | ,author="Paul E. McKenney and Dipankar Sarma and Maneesh Soni" | |
366 | ,title="Scaling dcache with {RCU}" | |
367 | ,Year="2004" | |
368 | ,Month="January" | |
369 | ,journal="Linux Journal" | |
370 | ,volume="1" | |
371 | ,number="118" | |
372 | ,pages="38-46" | |
373 | } | |
374 | ||
375 | @Conference{McKenney04b | |
376 | ,Author="Paul E. McKenney" | |
377 | ,Title="{RCU} vs. Locking Performance on Different {CPUs}" | |
378 | ,Booktitle="{linux.conf.au}" | |
379 | ,Month="January" | |
380 | ,Year="2004" | |
381 | ,Address="Adelaide, Australia" | |
382 | ,note="Available: | |
383 | \url{http://www.linux.org.au/conf/2004/abstracts.html#90} | |
384 | \url{http://www.rdrop.com/users/paulmck/rclock/lockperf.2004.01.17a.pdf} | |
385 | [Viewed June 23, 2004]" | |
386 | } | |
387 | ||
388 | @phdthesis{PaulEdwardMcKenneyPhD | |
389 | ,author="Paul E. McKenney" | |
390 | ,title="Exploiting Deferred Destruction: | |
391 | An Analysis of Read-Copy-Update Techniques | |
392 | in Operating System Kernels" | |
393 | ,school="OGI School of Science and Engineering at | |
394 | Oregon Health and Sciences University" | |
395 | ,year="2004" | |
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396 | ,note="Available: |
397 | \url{http://www.rdrop.com/users/paulmck/RCU/RCUdissertation.2004.07.14e1.pdf} | |
398 | [Viewed October 15, 2004]" | |
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399 | } |
400 | ||
401 | @Conference{Sarma04c | |
402 | ,Author="Dipankar Sarma and Paul E. McKenney" | |
403 | ,Title="Making RCU Safe for Deep Sub-Millisecond Response Realtime Applications" | |
404 | ,Booktitle="Proceedings of the 2004 USENIX Annual Technical Conference | |
405 | (FREENIX Track)" | |
406 | ,Publisher="USENIX Association" | |
407 | ,year="2004" | |
408 | ,month="June" | |
409 | ,pages="182-191" | |
410 | } | |
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411 | |
412 | @unpublished{JamesMorris04b | |
413 | ,Author="James Morris" | |
414 | ,Title="Recent Developments in {SELinux} Kernel Performance" | |
415 | ,month="December" | |
416 | ,year="2004" | |
417 | ,note="Available: | |
418 | \url{http://www.livejournal.com/users/james_morris/2153.html} | |
419 | [Viewed December 10, 2004]" | |
420 | } | |
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421 | |
422 | @unpublished{PaulMcKenney05a | |
423 | ,Author="Paul E. McKenney" | |
424 | ,Title="{[RFC]} {RCU} and {CONFIG\_PREEMPT\_RT} progress" | |
425 | ,month="May" | |
426 | ,year="2005" | |
427 | ,note="Available: | |
428 | \url{http://lkml.org/lkml/2005/5/9/185} | |
429 | [Viewed May 13, 2005]" | |
430 | ,annotation=" | |
431 | First publication of working lock-based deferred free patches | |
432 | for the CONFIG_PREEMPT_RT environment. | |
433 | " | |
434 | } | |
435 | ||
436 | @conference{PaulMcKenney05b | |
437 | ,Author="Paul E. McKenney and Dipankar Sarma" | |
438 | ,Title="Towards Hard Realtime Response from the Linux Kernel on SMP Hardware" | |
439 | ,Booktitle="linux.conf.au 2005" | |
440 | ,month="April" | |
441 | ,year="2005" | |
442 | ,address="Canberra, Australia" | |
443 | ,note="Available: | |
444 | \url{http://www.rdrop.com/users/paulmck/RCU/realtimeRCU.2005.04.23a.pdf} | |
445 | [Viewed May 13, 2005]" | |
446 | ,annotation=" | |
447 | Realtime turns into making RCU yet more realtime friendly. | |
448 | " | |
449 | } |