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2008-05-10BKL: revert back to the old spinlock implementationLinus Torvalds1-39/+81
The generic semaphore rewrite had a huge performance regression on AIM7 (and potentially other BKL-heavy benchmarks) because the generic semaphores had been rewritten to be simple to understand and fair. The latter, in particular, turns a semaphore-based BKL implementation into a mess of scheduling. The attempt to fix the performance regression failed miserably (see the previous commit 00b41ec2611dc98f87f30753ee00a53db648d662 'Revert "semaphore: fix"'), and so for now the simple and sane approach is to instead just go back to the old spinlock-based BKL implementation that never had any issues like this. This patch also has the advantage of being reported to fix the regression completely according to Yanmin Zhang, unlike the semaphore hack which still left a couple percentage point regression. As a spinlock, the BKL obviously has the potential to be a latency issue, but it's not really any different from any other spinlock in that respect. We do want to get rid of the BKL asap, but that has been the plan for several years. These days, the biggest users are in the tty layer (open/release in particular) and Alan holds out some hope: "tty release is probably a few months away from getting cured - I'm afraid it will almost certainly be the very last user of the BKL in tty to get fixed as it depends on everything else being sanely locked." so while we're not there yet, we do have a plan of action. Tested-by: Yanmin Zhang <yanmin_zhang@linux.intel.com> Cc: Ingo Molnar <mingo@elte.hu> Cc: Andi Kleen <andi@firstfloor.org> Cc: Matthew Wilcox <matthew@wil.cx> Cc: Alexander Viro <viro@ftp.linux.org.uk> Cc: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-18Convert asm/semaphore.h users to linux/semaphore.hMatthew Wilcox1-1/+1
Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
2008-04-17Add semaphore.h to kernel_lock.cMatthew Wilcox1-0/+1
kernel_lock.c uses DECLARE_MUTEX, up() and down() without explicitly including asm/semaphore.h. This is fragile and leaves it vulnerable to breakage during header reorganisations. Signed-off-by: Matthew Wilcox <willy@linux.intel.com>
2008-01-25sched: remove the !PREEMPT_BKL codeIngo Molnar1-123/+0
remove the !PREEMPT_BKL code. this removes 160 lines of legacy code. Signed-off-by: Ingo Molnar <mingo@elte.hu>
2007-10-20spelling fixes: lib/Simon Arlott1-1/+1
Spelling fix in lib/. Signed-off-by: Simon Arlott <simon@fire.lp0.eu> Signed-off-by: Adrian Bunk <bunk@kernel.org>
2006-07-03[PATCH] lockdep: prove spinlock rwlock locking correctnessIngo Molnar1-1/+6
Use the lock validator framework to prove spinlock and rwlock locking correctness. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@linux.intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-06-26spelling fixesAndreas Mohr1-2/+2
acquired (aquired) contiguous (contigious) successful (succesful, succesfull) surprise (suprise) whether (weather) some other misspellings Signed-off-by: Andreas Mohr <andi@lisas.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
2005-09-10[PATCH] spinlock consolidationIngo Molnar1-2/+1
This patch (written by me and also containing many suggestions of Arjan van de Ven) does a major cleanup of the spinlock code. It does the following things: - consolidates and enhances the spinlock/rwlock debugging code - simplifies the asm/spinlock.h files - encapsulates the raw spinlock type and moves generic spinlock features (such as ->break_lock) into the generic code. - cleans up the spinlock code hierarchy to get rid of the spaghetti. Most notably there's now only a single variant of the debugging code, located in lib/spinlock_debug.c. (previously we had one SMP debugging variant per architecture, plus a separate generic one for UP builds) Also, i've enhanced the rwlock debugging facility, it will now track write-owners. There is new spinlock-owner/CPU-tracking on SMP builds too. All locks have lockup detection now, which will work for both soft and hard spin/rwlock lockups. The arch-level include files now only contain the minimally necessary subset of the spinlock code - all the rest that can be generalized now lives in the generic headers: include/asm-i386/spinlock_types.h | 16 include/asm-x86_64/spinlock_types.h | 16 I have also split up the various spinlock variants into separate files, making it easier to see which does what. The new layout is: SMP | UP ----------------------------|----------------------------------- asm/spinlock_types_smp.h | linux/spinlock_types_up.h linux/spinlock_types.h | linux/spinlock_types.h asm/spinlock_smp.h | linux/spinlock_up.h linux/spinlock_api_smp.h | linux/spinlock_api_up.h linux/spinlock.h | linux/spinlock.h /* * here's the role of the various spinlock/rwlock related include files: * * on SMP builds: * * asm/spinlock_types.h: contains the raw_spinlock_t/raw_rwlock_t and the * initializers * * linux/spinlock_types.h: * defines the generic type and initializers * * asm/spinlock.h: contains the __raw_spin_*()/etc. lowlevel * implementations, mostly inline assembly code * * (also included on UP-debug builds:) * * linux/spinlock_api_smp.h: * contains the prototypes for the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. * * on UP builds: * * linux/spinlock_type_up.h: * contains the generic, simplified UP spinlock type. * (which is an empty structure on non-debug builds) * * linux/spinlock_types.h: * defines the generic type and initializers * * linux/spinlock_up.h: * contains the __raw_spin_*()/etc. version of UP * builds. (which are NOPs on non-debug, non-preempt * builds) * * (included on UP-non-debug builds:) * * linux/spinlock_api_up.h: * builds the _spin_*() APIs. * * linux/spinlock.h: builds the final spin_*() APIs. */ All SMP and UP architectures are converted by this patch. arm, i386, ia64, ppc, ppc64, s390/s390x, x64 was build-tested via crosscompilers. m32r, mips, sh, sparc, have not been tested yet, but should be mostly fine. From: Grant Grundler <grundler@parisc-linux.org> Booted and lightly tested on a500-44 (64-bit, SMP kernel, dual CPU). Builds 32-bit SMP kernel (not booted or tested). I did not try to build non-SMP kernels. That should be trivial to fix up later if necessary. I converted bit ops atomic_hash lock to raw_spinlock_t. Doing so avoids some ugly nesting of linux/*.h and asm/*.h files. Those particular locks are well tested and contained entirely inside arch specific code. I do NOT expect any new issues to arise with them. If someone does ever need to use debug/metrics with them, then they will need to unravel this hairball between spinlocks, atomic ops, and bit ops that exist only because parisc has exactly one atomic instruction: LDCW (load and clear word). From: "Luck, Tony" <tony.luck@intel.com> ia64 fix Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjanv@infradead.org> Signed-off-by: Grant Grundler <grundler@parisc-linux.org> Cc: Matthew Wilcox <willy@debian.org> Signed-off-by: Hirokazu Takata <takata@linux-m32r.org> Signed-off-by: Mikael Pettersson <mikpe@csd.uu.se> Signed-off-by: Benoit Boissinot <benoit.boissinot@ens-lyon.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-06-21[PATCH] smp_processor_id() cleanupIngo Molnar1-55/+0
This patch implements a number of smp_processor_id() cleanup ideas that Arjan van de Ven and I came up with. The previous __smp_processor_id/_smp_processor_id/smp_processor_id API spaghetti was hard to follow both on the implementational and on the usage side. Some of the complexity arose from picking wrong names, some of the complexity comes from the fact that not all architectures defined __smp_processor_id. In the new code, there are two externally visible symbols: - smp_processor_id(): debug variant. - raw_smp_processor_id(): nondebug variant. Replaces all existing uses of _smp_processor_id() and __smp_processor_id(). Defined by every SMP architecture in include/asm-*/smp.h. There is one new internal symbol, dependent on DEBUG_PREEMPT: - debug_smp_processor_id(): internal debug variant, mapped to smp_processor_id(). Also, i moved debug_smp_processor_id() from lib/kernel_lock.c into a new lib/smp_processor_id.c file. All related comments got updated and/or clarified. I have build/boot tested the following 8 .config combinations on x86: {SMP,UP} x {PREEMPT,!PREEMPT} x {DEBUG_PREEMPT,!DEBUG_PREEMPT} I have also build/boot tested x64 on UP/PREEMPT/DEBUG_PREEMPT. (Other architectures are untested, but should work just fine.) Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Arjan van de Ven <arjan@infradead.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-04-16Linux-2.6.12-rc2Linus Torvalds1-0/+264
Initial git repository build. I'm not bothering with the full history, even though we have it. We can create a separate "historical" git archive of that later if we want to, and in the meantime it's about 3.2GB when imported into git - space that would just make the early git days unnecessarily complicated, when we don't have a lot of good infrastructure for it. Let it rip!

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