FreeBSD SMP プロジェクト (しばしば SMPng (次世代 SMP) と 呼ばれます) は FreeBSD 5.0 カーネル (2002年11月を予定) 向けの fine-grained な SMP サポートを実装することに集中 しています。 FreeBSD の歴史のため、これは丸い穴に四角いくさびを打ち込むような 作業であり、途中経過はあまり美しいものとはいえません。; 私たちはカーネルを一から書き直そうとはしていませんし、 今のカーネルにある問題点の全てを修正しようとしている わけでもありません。 実際、私たちは FreeBSD 5.0 がリリースされるときに、 構造上の問題点の痕跡が、様々な形でそれとわかるように残しておく つもりです。 これは理論的なプロジェクトというよりは、実際的なものであり、 この一年間カーネルがうまく働き、安定して動作するようにしておく 必要があります。 なので、時間的制約からも私たちはいつ何をしなければならないのか について現実的でなければなりません。
このウェブページには FreeBSD における SMP サポートの改良 に関する情報が掲載されています。 一般に、このプロジェクトは BSD/OS 5.0 開発版カーネルで 使われているものを用い、コードベースの違いから そのまま使うことができないものに関しては再実装するように しています。
他のフリーソフトウェアプロジェクトと同様に、詳細なスケジュール を立てることはできません。 私たちはこのプロジェクトの最初の数ヵ月で、うまく動作しつつ 大幅な性能改善と安定性を得ることを期待しています。 そして、それらは -current ができるかぎりちゃんと働き続ける ようにして行われなければなりません。
Most SMP-related discussion takes place on the freebsd-smp メーリングリスト。 FreeBSD ハンドブック の インターネット上のリソース にメーリングリストに関する詳しい情報が載っています。
Steve Passe は将来的にこのページに統合されるであろう 追加情報を含む SMP プロジェクトページ を管理しています。
&dillon; は彼が SMP プロジェクトで何をしているのか についての ウェブページ を管理しています。
この一般タスクリストは完全ではありません。
| タスク | 担当者 | 最終更新 | ステータス |
|---|---|---|---|
| Convert the giant lock from spinning to blocking, add the scheduler lock, add per-CPU idle processes. | &dillon; | 25 June 2000 | &status.done; |
| Port the BSD/OS locking primitives (i386). | &jake; | 3 July 2000 | &status.done; |
| Implement heavy-weight interrupt threads (i386). | &grog; | 3 August 2000 | &status.done; |
| Rewrite the low level interrupt code (i386 UP). | &grog; | 3 August 2000 | &status.done; |
| Demonstrated reasonable stability (self-hosted buildworld) (i386 UP). | -smp developers | 12 August 2000 | &status.done; |
| Port the BSD/OS locking primitives (alpha). | 𝔡 | 24 August 2000 | &status.done; |
| Stub out (disable) spl()s. | &grog; | 30 August 2000 | &status.done; |
| Port the BSD/OS ktr code. | &grog;, &jhb; | 30 August 2000 | &status.done; |
| Rewrite the low level interrupt code (i386 SMP). | &jhb; | 1 September 2000 | &status.done; |
| Demonstrated reasonable stability (self-hosted buildworld) (i386 SMP). | -smp developers | 6 September 2000 | &status.done; |
| Demonstrated reasonable stability (self-hosted buildworld) (alpha). | -smp developers | 6 September 2000 | &status.done; |
| Make malloc and friends thread-safe. | &jasone; | 10 September 2000 | &status.done; |
| Implement msleep(), make tsleep() an msleep() wrapper. | &jake; | 11 September 2000 | &status.done; |
| Make fxp driver thread-safe. | &cp; | 17 September 2000 | &status.done; |
| Make mbuf's thread-safe. | &bmilekic; | 29 September 2000 | &status.done; |
| Lock manager re-work. | &jasone; | 3 October 2000 | &status.done; |
| Implement heavy-weight interrupt threads (alpha). | &jhb;, 𝔡 | 5 October 2000 | &status.done; |
| Rewrite the low level interrupt code (alpha). | 𝔡, &jhb; | 5 October 2000 | &status.done; |
| Process accounting. | Tor Egge, &jhb; | 5 October 2000 | &status.done; |
| Make ethernet drivers thread-safe. | Bill Paul | 15 October 2000 | &status.done; |
| Make the mutex headers mostly machine-independent. | &jhb; | 20 October 2000 | &status.done; |
| Rename SMP_DEBUG to MUTEX_DEBUG. | &jhb; | 20 October 2000 | &status.done; |
| Give each soft interrupt its own thread. | &cp; | 25 October 2000 | &status.done; |
| Make sf_bufs (sendfile(2)) thread-safe. | &bmilekic; | 5 November 2000 | &status.done; |
| Make the witness code work correctly. | &jhb; | 18 November 2000 | &status.done; |
| Split the ktr-specific code out of db_interface.c. | &jhb; | 15 December 2000 | &status.done; |
| Convert the sio driver to using a spin mutex. | &jhb; | 18 December 2000 | &status.done; |
| Implement condition variables. | &jake;, &jasone; | 15 January 2001 | &status.done; |
| Add a flag to mtx_init() (MTX_RECURSE) that denotes whether a mutex is allowed to recurse. | &bmilekic; | 19 January 2001 | &status.done; |
| Make the zone allocator thread-safe. | Dag-Erling Smorgrav | 21 January 2001 | &status.done; |
| Convert simplelocks to mutexes. | &jasone; | 24 January 2001 | &status.done; |
| Make kernel preemptive with respect to interrupts. | &jake; | 31 January 2001 | &status.done; |
| Cleanup of mutex API. | &bmilekic; | 8 February 2001 | &status.done; |
| Remove COM_LOCK. | &markm; | 11 February 2001 | &status.done; |
| Merge various scheduling classes into one run queue. Modify scheduler to support preemptable kernel. | &jake; | 11 February 2001 | &status.done; |
| Make priority propagation work correctly. | &jake; | 11 February 2001 | &status.done; |
| Make most of the interrupt thread code MI and shared between hardware and software interrupts. | &jhb; | 18 February 2001 | &status.done; |
| Implement sx (shared/exclusive) locks. | &jasone; | 5 March 2001 | &status.done; |
| Generalize/improve witness to handle more complex locking primitives (mtx, sx). | &jhb; | 28 March 2001 | &status.done; |
| Convert the allproc and proctree locks from lockmgr locks to sx locks. | &jhb; | 28 March 2001 | &status.done; |
| Make mbuf system use condition variables instead of msleep()/wakeup(). | &bmilekic; | 2 April 2001 | &status.done; |
| Remove <sys/mutex.h> includes from other kernel headers such as <vm/vm_zone.h>, <sys/resourcevar.h>, <sys/ucred.h>, and <sys/mbuf.h>. | &markm; | 15 May 2001 | &status.done; |
| Cleanup the various mp_machdep.c's, unify various SMP API's such as IPI delivery, etc. | &jhb; | 15 May 2001 | &status.done; |
| Make most of the forward_* and forwarded_* functions MI. | &jhb; | 15 May 2001 | &status.done; |
| Complete the MD support for SMP on the Alpha platform. | &gallatin;, 𝔡, &jhb; | 15 May 2001 | &status.done; |
| Convert select() to use condition variables. | &tanimura; | 15 May 2001 | &status.done; |
| Add a "giant" lock around the VM subsystem. | &alfred; | 13 June 2001 | &status.done; |
| Introduce a modified slab allocator for the mbuf subsystem. | &bmilekic; | 21 June 2001 | &status.done; |
| Add a witness_assert() function to handle lock assertions. | &jhb; | 27 June 2001 | &status.done; |
| Extend sx locks to support try lock operations. | &jhb; | 27 June 2001 | &status.done; |
| Document KTR. | &jhb; | 28 June 2001 | &status.done; |
| Make fork_return, fork_exit, ast, and userret MI. | &jhb; | 29 June 2001 | &status.done; |
| Make sched_lock's savecrit a per-process property saved and restored in mi_switch and initialized in fork_exit. | &jhb; | 30 June 2001 | &status.done; |
| Make ast() loop. | &jhb; | 10 August 2001 | &status.done; |
| Add upgrade/downgrade sx lock operations. | Alexander Kabaev, &jasone; | 13 August 2001 | &status.done; |
| Implement semaphores. | &jasone; | 14 August 2001 | &status.done; |
| Add support for upgrade/downgrades in witness. | &jhb; | 23 August 2001 | &status.done; |
| Remove the MP safe syscall flag from the syscall table and add explicit mtx_lock/unlock's of Giant to all syscalls. | &dillon; | 7 September 2001 | &status.done; |
| Make most of cpu_wait() and cpu_exit() MI. | &peter; | 9 September 2001 | &status.done; |
| Split NFS into client and server. | &peter; | 18 Oct 2001 | &status.done; |
| Lock taskqueues. | Andrew Reiter, &jhb; | 25 October 2001 | &status.done; |
| Add a per-thread ucred reference. | &jhb; | 25 October 2001 | &status.done; |
| Make most of the per-CPU stuff MI. | &jhb; | 11 December 2001 | &status.done; |
| Make critical section saved state per-thread instead of per-lock so that interlocking spin locks work properly. | &jhb; | 17 December 2001 | &status.done; |
| Replace the APIC-specific imen_mtx with a MI-named icu_lock to protect interrupt controllers and associated data within the kernel for both i386 and alpha. | &jhb; | 20 December 2001 | &status.done; |
| Use the per-thread critical section nesting level in the mutex and interrupt thread code to automatically determine when to not preempt. This makes the MTX_NOSWITCH, SWI_SWITCH, and SWI_NOSWITCH flags obslete as the kernel will be able to figure out the proper behavior on its own. | &jhb; | 5 January 2002 | &status.done; |
| Lock struct filedesc and struct file. | &tanimura;, &alfred; | 12 January 2002 | &status.done; |
| Lock struct proc. | &jhb; | 20 February 2001 | &status.wip; |
| Lock struct pgrp, struct session, and struct sigio. | &tanimura; | 13 June 2001 | &status.wip; |
| Make KTRACE write into tracefiles asynchronously. | &jhb; | 6 September 2001 | &status.wip; |
| Make the kernel fully preemptive. | &jhb; | 7 September 2001 | &status.wip; |
| Convert vm_map locks to sx locks. | &green; | 18 October 2001 | &status.wip; |
| Lock down the tty subsystem. | Dick Garner, Jeremy Scofield | 16 November 2001 | &status.wip; |
| Fix clock locking to be the same on all platforms. | &jhb; | 16 November 2001 | &status.wip; |
| Make sleep mutexes spin if the current lock holder is executing on another CPU. | &jhb; | 16 November 2001 | &status.wip; |
| Add support for the IA32 pause instruction to spin loops in locks. | &jhb; | 16 November 2001 | &status.wip; |
| Optimize UP support by changing spin locks to only perform critical section enter and exits. | &jhb; | 20 December 2001 | &status.wip; |
| Implement lazy interrupt thread switching (context stealing) on i386. | &bmilekic; | 4 January 2002 | &status.wip; |
| Fix synchronization of TLB flushes and invlpg() on x86 SMP. | &peter; | 4 January 2002 | &status.wip; |
| Create mechanism in cdevsw structure to protect thread-unsafe drivers. | &jhb; | 15 May 2001 | &status.stalled; |
| Make printf() safe to call in almost any situation to avoid deadlocks. | &cp; | 15 May 2001 | &status.stalled; |
| Implement trap handler for cmpxchgl on 80386 to support generic userland atomic operations. | &jake; | 15 May 2001 | &status.stalled; |
| Add locking to NFS. | 15 May 2001 | &status.new; | |
| Use per-CPU buffers for ktr to reduce synchronization. | 5 September 2000 | &status.new; | |
| Remove priority argument from tsleep(), msleep(), cv_*wait*(). | 12 January 2001 | &status.new; | |
| Reimplement kqueue using condition variables. | &jlemon; | 15 March 2001 | &status.new; |
| Conditionalize atomic ops in the SMP code that are used for debugging statistics. | &peter; | 15 March 2001 | &status.new; |
| Add a new witness check for exiting processes to verify that an exiting process holds no locks. | &jhb; | 13 June 2001 | &status.new; |
| Make cpu_core MI. | 13 June 2001 | &status.new; | |
| Lock struct pargs. | 20 June 2001 | &status.new; | |
| Specify priorities for condition variables, semaphores, and sx locks. | 7 September 2001 | &status.new; | |
| Fix SIGXPU and other #if 0'd things in mi_switch(). | 7 September 2001 | &status.new; | |
| Axe schedpu() in favor of event driven priority updates as much as possible. | 7 September 2001 | &status.new; | |
| Fix PHOLD() so that it blocks to guarantee PS_INMEM. | 7 September 2001 | &status.new; | |
| Make grow_stack() MI. Possibly even a macro or inline. | 7 September 2001 | &status.new; | |
| Fix *hold (e.g. crhold) to return reference to object. | 7 September 2001 | &status.new; | |
| Fix various procfs_machdep.c to use PHOLD, not sched_lock. | 7 September 2001 | &status.new; | |
| Convert eventhandlers to sx locks. | 7 September 2001 | &status.new; | |
| Add witness checking for lockmgr locks. | 7 September 2001 | &status.new; | |
| Add ICU spin locks on ia64 and sparc64. | 4 January 2002 | &status.new; |
This table lists the todo subtasks for multithreading the network stack.
| Task | Responsible | Last updated | Status |
|---|---|---|---|
| Protect network interface queues. | &jlemon; | 24 November 2000 | &status.done; |
| Lock struct ifnet. | 19 January 2001 | &status.new; |
| Issue | Last updated | Status |
|---|---|---|
| Idle processor time is not charged to the idle processes. | 20 September 2000 | &status.resolved; |
| microuptime creeps backwards. | 4 October 2000 | &status.resolved; |
| microuptime() went backwards | 4 October 2000 | &status.resolved; |
| Process accounting is not accurate (the more CPUs, the closer to correct it is). | 5 October 2000 | &status.resolved; |
| M_DEVBUF is probably the wrong memory pool for interrupt stuff and we should think about creating a new malloc pool for that stuff. | 9 February 2001 | &status.resolved; |
| PC card eject panics due to a race condition in the interrupt thread code. | 15 March 2001 | &status.resolved; |
| SMP x86 boxes are seeing NCPU * 100 clk interrupts and NCPU * 128 rtc interrupts. | 15 May 2001 | &status.resolved; |
| Witness will infinitely recurse when it acquires Giant after sleeping with a sleepable lock. | 27 June 2001 | &status.resolved; |
| Serial gdb does not work if boot_ddb and boot_gdb options are specified. | 5 September 2000 | &status.unresolved; |
| Serial gdb does not work at 115200 baud. | 5 September 2000 | &status.unresolved; |
| Profiling is broken. | 20 February 2001 | &status.unresolved; |
このページの残りは新しいものから順に並んでいます。
15 May 2001&grog; has made his USENIX paper available, which he will present in Boston at the end of June.
A status report was sent to the -smp mailing list.
A status report was sent to the -smp mailing list.
A status report was sent to the -smp mailing list.
A status report was sent to the -smp mailing list.
&jhb; and &cp; came up with a preliminary list of rules that should be followed when working on kernel synchronization.
Here's a copy of an article sent to BSDtoday and linked at Daemon News.
The SMP code has been committed. All further work is being done in cvs rather than with patches.
An updated patch is available for download. This patch is proably what will actually get committed.
An updated patch is available for download. This patch makes rtc a fast interrupt, uses locked instructions for mutexes in MP kernels, and corrects mtx_*() linkage within modules.
The code is working for the most part now on i386 (UP and MP). Some additional coding is still necessary for the alpha, which is being done now.
Updated patches for i386 and alpha are available here.
Updated patches for i386 are available here. Process accounting still doesn't work correctly, but a number of other improvements have been made.
Patches with functional heavy-weight threads for the i386 platform are available here. There are a couple of minor issues with this patch set. Specifically, process accounting doesn't work correctly.
Sheldon Hearn has prepared a mutex(9) man page based on the BSD/OS one, which is available here.
&jake; put an updated patch here.
&jake; has the BSD/OS lock code working now, and has incorporated the pertinent portions of &dillon;'s patches (idle processes, some of the schedlock changes, etc.). His patch set is available here.
&cp; has provided the PostScript versions of his presentation slides for the first day and second day of the SMP meeting.
Here's a copy of the SMP meeting summary that was posted to the -smp mailing list.
Here's a copy of the SMP project announcement that was posted to the -current mailing list.