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By isolating the kernel from concurrency, many parts of the kernel no longer need to be modified to support SMP. However, as in giant-lock SMP systems only one processor can run the kernel code at a time, performance for applications spending significant amounts of time in the kernel is not much
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improved. Accordingly, the giant-lock approach is commonly seen as a preliminary means of bringing SMP support to an operating system, yielding benefits only in user space. Most modern operating systems use a
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family of primitives to facilitate synchronisation of critical sections within the kernel, meaning that many system calls may inhibit SMP capabilities of the system, and, according to
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78:, but no more than one thread can run in kernel space; any other threads that try to enter kernel space are forced to wait. In other words, the giant lock eliminates all
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Foundation views modern SMP support as vital to the direction of The NetBSD Project, and has offered grants to developers willing to work on SMP improvements;
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Giant is a special mutex used to protect data structures that do not yet have their own locks. Since it provides semantics akin to the old spl(9) interface, …
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was one of the projects that arose as a result of these financial incentives, but further improvements to the core networking stack may still be necessary.
164:, which provides semantics akin to the old spl interface, but performance-critical core components have long been converted to use finer-grained locking.
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removed it in 2011 in kernel version 2.6.39, with the remaining uses of the big lock removed or replaced by finer-grained locking.
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is the archetypal example. In this model, threads in user space can run concurrently on any available
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patch RFC 19/29 - printk: Add basic infrastructure for non-BKL consoles
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which are sometimes referred as BKL and its removal is in progress.
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had a big kernel lock (BKL) since the introduction of SMP, until
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A giant lock is a solitary global lock that is held whenever a
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472:"DragonFlyBSD Project Update - colo upgrade, future trends"
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PATCH - fbcon: Make fbcon a built-time depency for fbdev
545:"SMP Networking (aka remove the big network lock)"
437:"splx(9) — modify system interrupt priority level"
125:As of September 2022, Linux kernel still has
525:"locking -- kernel synchronization primitives".
501:"locking(9) — kernel synchronization primitives"
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345:rtnl mutex, the network stack big kernel lock
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253:"Before & After Under The Giant Lock"
175:general-purpose operating systems, only
62:and released when the thread returns to
309:https://kernelnewbies.org/BigKernelLock
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335:. Thomas Gleixner. September 11, 2022
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311:– BigKernelLock at kernelnewbies.org
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347:. Florian Westphal. November 2017
555:from the original on 2019-07-25
323:. Daniel Vetter. June 28, 2017
187:have modern SMP support, with
160:FreeBSD still has support for
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122:are therefore not using BKL.
16:Lock used in computer kernels
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359:. Kuniyuki Iwashima. 2024
49:symmetric multiprocessing
499:Julian Elischer (2007).
39:that may be used in the
226:Global interpreter lock
221:Lock (computer science)
141:As of July 2019,
283:BKL: that's all folks
528:FreeBSD Manual Pages
173:open-source software
149:are still using the
88:fine-grained locking
580:Concurrency control
505:BSD Cross Reference
409:BSD Cross Reference
374:BSD Cross Reference
108:Linux distributions
45:concurrency control
216:Parallel computing
27:, also known as a
281:"git.kernel.org:
249:Robert N M Watson
167:It is claimed by
116:Debian 7 (Wheezy)
82:in kernel space.
21:operating systems
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478:(Mailing list).
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287:. Archived from
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259:(Mailing list).
257:FreeBSD-Hackers@
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195:falling behind.
171:that out of the
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162:the Giant mutex
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76:processor cores
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551:. 2013-02-14.
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470:(2019-07-22).
468:Matthew Dillon
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357:Per Netns RTNL
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251:(2007-11-25).
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204:NPF (firewall)
169:Matthew Dillon
155:Matthew Dillon
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480:DragonFly BSD
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424:s = splnet();
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389:s = splnet();
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291:on 2012-07-20
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181:DragonFly BSD
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104:Arnd Bergmann
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557:. Retrieved
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415:. 2019-07-25
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382:. Retrieved
380:. 2019-06-30
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293:. Retrieved
289:the original
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264:. Retrieved
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127:console_lock
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120:Ubuntu 11.10
110:at or above
100:Linux kernel
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60:kernel space
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47:required by
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80:concurrency
68:system call
43:to provide
33:kernel-lock
559:2023-03-26
514:2019-07-25
485:2019-07-25
450:2019-07-25
419:2019-07-25
384:2019-07-25
295:2019-12-28
266:2019-07-25
232:References
90:approach.
72:processors
64:user space
25:giant lock
131:rtnl_lock
574:Category
553:Archived
210:See also
112:CentOS 7
29:big-lock
509:FreeBSD
445:OpenBSD
378:OpenBSD
261:FreeBSD
189:OpenBSD
185:FreeBSD
143:OpenBSD
58:enters
35:, is a
549:NetBSD
476:users@
441:NetBSD
413:NetBSD
200:NetBSD
193:NetBSD
147:NetBSD
56:thread
41:kernel
177:Linux
94:Linux
198:The
191:and
183:and
145:and
129:and
118:and
98:The
66:; a
37:lock
23:, a
151:spl
137:BSD
74:or
31:or
19:In
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459:^
443:,
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396:^
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240:^
179:,
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