- 08 Jan, 2005 40 commits
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Ingo Molnar authored
SMP locking latencies are one of the last architectural problems that cause millisec-category scheduling delays. CONFIG_PREEMPT tries to solve some of the SMP issues but there are still lots of problems remaining: spinlocks nested at multiple levels, spinning with irqs turned off, and non-nested spinning with preemption turned off permanently. The nesting problem goes like this: if a piece of kernel code (e.g. the MM or ext3's journalling code) does the following: spin_lock(&spinlock_1); ... spin_lock(&spinlock_2); ... then even with CONFIG_PREEMPT enabled, current kernels may spin on spinlock_2 indefinitely. A number of critical sections break their long paths by using cond_resched_lock(), but this does not break the path on SMP, because need_resched() *of the other CPU* is not set so cond_resched_lock() doesnt notice that a reschedule is due. to solve this problem i've introduced a new spinlock field, lock->break_lock, which signals towards the holding CPU that a spinlock-break is requested by another CPU. This field is only set if a CPU is spinning in a spinlock function [at any locking depth], so the default overhead is zero. I've extended cond_resched_lock() to check for this flag - in this case we can also save a reschedule. I've added the lock_need_resched(lock) and need_lockbreak(lock) methods to check for the need to break out of a critical section. Another latency problem was that the stock kernel, even with CONFIG_PREEMPT enabled, didnt have any spin-nicely preemption logic for the following, commonly used SMP locking primitives: read_lock(), spin_lock_irqsave(), spin_lock_irq(), spin_lock_bh(), read_lock_irqsave(), read_lock_irq(), read_lock_bh(), write_lock_irqsave(), write_lock_irq(), write_lock_bh(). Only spin_lock() and write_lock() [the two simplest cases] where covered. In addition to the preemption latency problems, the _irq() variants in the above list didnt do any IRQ-enabling while spinning - possibly resulting in excessive irqs-off sections of code! preempt-smp.patch fixes all these latency problems by spinning irq-nicely (if possible) and by requesting lock-breaks if needed. Two architecture-level changes were necessary for this: the addition of the break_lock field to spinlock_t and rwlock_t, and the addition of the _raw_read_trylock() function. Testing done by Mark H Johnson and myself indicate SMP latencies comparable to the UP kernel - while they were basically indefinitely high without this patch. i successfully test-compiled and test-booted this patch ontop of BK-curr using the following .config combinations: SMP && PREEMPT, !SMP && PREEMPT, SMP && !PREEMPT and !SMP && !PREEMPT on x86, !SMP && !PREEMPT and SMP && PREEMPT on x64. I also test-booted x86 with the generic_read_trylock function to check that it works fine. Essentially the same patch has been in testing as part of the voluntary-preempt patches for some time already. NOTE to architecture maintainers: generic_raw_read_trylock() is a crude version that should be replaced with the proper arch-optimized version ASAP. From: Hugh Dickins <hugh@veritas.com> The i386 and x86_64 _raw_read_trylocks in preempt-smp.patch are too successful: atomic_read() returns a signed integer. Signed-off-by:
Ingo Molnar <mingo@elte.hu> Signed-off-by:
Hugh Dickins <hugh@veritas.com> Signed-off-by:
Andrew Morton <akpm@osdl.org> Signed-off-by:
Linus Torvalds <torvalds@osdl.org>
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Nathan Lynch authored
Call idle_task_exit from cpu_die to avoid mm_struct leak. Signed-off-by:
Nathan Lynch <nathanl@austin.ibm.com> Signed-off-by:
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Nathan Lynch authored
Heiko Carstens figured out that offlining a cpu can leak mm_structs because the dying cpu's idle task fails to switch to init_mm and mmdrop its active_mm before the cpu is down. This patch introduces idle_task_exit, which allows the idle task to do this as Ingo suggested. I will follow this up with a patch for ppc64 which calls idle_task_exit from cpu_die. Signed-off-by:
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Josh Aas authored
This patch removes two outdated/misleading comments from the CPU scheduler. 1) The first comment removed is simply incorrect. The function it comments on is not used for what the comments says it is anymore. 2) The second comment is a leftover from when the "if" block it comments on contained a goto. It does not any more, and the comment doesn't make sense. There isn't really a reason to add different comments, though someone might feel differently in the case of the second one. I'll leave adding a comment to anybody who wants to - more important to just get rid of them now. Signed-off-by:
Josh Aas <josha@sgi.com> Acked-by:
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Dean Nelson authored
This patch exports sched_setscheduler() so that it can be used by a kernel module to set a kthread's scheduling policy and associated parameters. Signed-off-by:
Dean Nelson <dcn@sgi.com> Acked-by:
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Robert Love authored
no need to call task_rq in setscheduler; just use rq Signed-Off-By:
Robert Love <rml@novell.com> Acked-by:
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Oleg Nesterov authored
Replace open-coded thread_group_leader() calls. Signed-off-by:
Oleg Nesterov <oleg@tv-sign.ru> Acked-by:
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Oleg Nesterov authored
schedule() can use prev instead of get_current(). Signed-off-by:
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Con Kolivas authored
Special casing tasks by interactive credit was helpful for preventing fully cpu bound tasks from easily rising to interactive status. However it did not select out tasks that had periods of being fully cpu bound and then sleeping while waiting on pipes, signals etc. This led to a more disproportionate share of cpu time. Backing this out will no longer special case only fully cpu bound tasks, and prevents the variable behaviour that occurs at startup before tasks declare themseleves interactive or not, and speeds up application startup slightly under certain circumstances. It does cost in interactivity slightly as load rises but it is worth it for the fairness gains. Signed-off-by:
Con Kolivas <kernel@kolivas.org> Acked-by:
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Con Kolivas authored
Change the granularity code to requeue tasks at their best priority instead of changing priority while they're running. This keeps tasks at their top interactive level during their whole timeslice. Signed-off-by:
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Con Kolivas authored
We can requeue tasks for cheaper then doing a complete dequeue followed by an enqueue. Add the requeue_task function and perform it where possible. This will be hit frequently by upcoming changes to the requeueing in timeslice granularity. Signed-off-by:
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Con Kolivas authored
The minimum timeslice was decreased from 10ms to 5ms. In the process, the timeslice granularity was leading to much more rapid round robinning of interactive tasks at cache trashing levels. Restore minimum granularity to 10ms. Signed-off-by:
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Con Kolivas authored
Timeslice proportion has been increased substantially for -niced tasks. As a result of this kernel threads have much larger timeslices than they previously had. Change kernel threads' nice value to -5 to bring their timeslice back in line with previous behaviour. This means kernel threads will be less likely to cause large latencies under periods of system stress for normal nice 0 tasks. Signed-off-by:
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Con Kolivas authored
Convert whitespace in sched.c to tabs Signed-off-by:
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Anton Blanchard authored
Reset cache_hot_time to sane values (in the ms range). Some recent changes resulted in values in the us range. Signed-off-by:
Anton Blanchard <anton@samba.org> Signed-off-by:
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Matthew Dobson authored
There is a small problem with the active_load_balance() patch that Darren sent out last week. As soon as we discover a potential 'target_cpu' from 'cpu_group' to try to push tasks to, we cease considering other CPUs in that group as potential 'target_cpu's. We break out of the for_each_cpu_mask() loop and try to push tasks to that CPU. The problem is that there may well be other idle cpus in that group that we should also try to push tasks to. Here is a patch to fix that small problem. The solution is to simply move the code that tries to push the tasks into the for_each_cpu_mask() loop and do away with the whole 'target_cpu' thing entirely. Compiled & booted on a 16-way x440. Signed-off-by:
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Andrew Theurer authored
Allow idle_balance to search an incresingly larger span of cpus to find a cpu. Minor change, NODE_SD_INIT gets SD_BALANCE_NEWIDLE flag. This is critical for x86_64, where there is only one cpu oer node. In the current code, idle_balance for Opteron -never- works. Signed-off-by: <habanero@us.ibm.com> Signed-off-by:
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Andrew Theurer authored
Fix can_migrate to allow aggressive steal for idle cpus. This -was- in mainline, but I believe sched_domains kind of blasted it outta there. IMO, it's a no brainer for an idle cpu (with all that cache going to waste) to be granted to steal a task. The one enhancement I have made was to make sure the whole cpu was idle. Signed-off-by: <habanero@us.ibm.com> Signed-off-by:
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Andrew Theurer authored
This patch addresses some problems with wake_idle(). Currently wake_idle() will wake a task on an alternate cpu if: 1) task->cpu is not idle 2) an idle cpu can be found However the span of cpus to look for is very limited (only the task->cpu's sibling). The scheduler should find the closest idle cpu, starting with the lowest level domain, then going to higher level domains if allowed (doamin has flag SD_WAKE_IDLE). This patch does this. This and the other two patches (also to be submitted) combined have provided as much at 5% improvement on that "online transaction DB workload" and 2% on the industry standard J@EE workload. I asked Martin Bligh to test these for regression, and he did not find any. I would like to submit for inclusion to -mm and barring any problems eventually to mainline. Signed-off-by: <habanero@us.ibm.com> Signed-off-by:
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Neil Brown authored
Avoid unlock-without-lock problem on error path in nfsd4_setclientid_confirm Signed-off-by:
Neil Brown <neilb@cse.unsw.edu.au> Signed-off-by:
J. Bruce Fields <bfields@citi.umich.edu> Signed-off-by:
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Greg Banks authored
With Keith Owens <kaos@sgi.com> This patch from Keith Owens fixes a bug in the ia64 port of oprofile when built without the kdb patch and with a pre-3.4 gcc. If you build a standard kernel with gcc < 3.4 then ia64_spinlock_contention_pre3_4 is defined. But a standard kernel does not have ia64_spinlock_contention_pre3_4_end, that label is only added by the kdb patch. To get the backtrace profiling with gcc < 3.4, the _end label needs to be added as part of the kernprof patch, then I will remove it from kdb. Signed-off-by:
Keith Owens <kaos@sgi.com> Signed-off-by:
Greg Banks <gnb@melbourne.sgi.com> Signed-off-by:
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Thayne Harbaugh authored
This patch makes several tweaks so that an initramfs image can be completely created by an unprivileged user. It should maintain compatibility with previous initramfs early userspace cpio/image creation and it updates documentation. There are a few very important tweaks: CONFIG_INITRAMFS_SOURCE is now either a single cpio archive that is directly used or a list of directories and files for building a cpio archive for the initramfs image. Making the cpio archive listable in CONFIG_INITRAMFS_SOURCE makes the cpio step more official and automated so that it doesn't have to be copied by hand to usr/initramfs_data.cpio (I think this was broken anyway and would be overwritten). The alternative list of directories *and* files means that files can be install in a "root" directory and device-special files can be listed in a file list. CONFIG_ROOT_UID and CONFIG_ROOT_GID are now available for doing simple user/group ID translation. That means that user ID 500, group ID 500 can create all the files in the "root" directory, but that they can all be owned by user ID 0, group ID 0 in the cpio image. Various documentation updates to pull it all together. Removal of old cruft that was unused/misleading. Signed-off-by:
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Theodore Y. Ts'o authored
telldir() is broken on large ext3 dir_index'd directories because getdents() gives d_off==0 for the first entry Here's a patch which fixes the problem, but note the following warning from the readdir man page: According to POSIX, the dirent structure contains a field char d_name[] of unspecified size, with at most NAME_MAX characters preceding the terminating null character. Use of other fields will harm the porta- bility of your programs. Also, as always, telldir() and seekdir() are truly awful interfaces because they implicitly assume that (a) a directory is a linear data structure, and (b) that the position in a directory can be expressed in a cookie which hsa only 31 bits on 32-bit systems. So there will be hash colliions that will cause programs that assume that seekdir(dirent->d_off) will always return the next directory entry to sometimes lose directory entries in the not-as-unlikely-as-we-would wish case of a 31-bit hash collision. Really, any program which is using telldir/seekdir really should be rewritten to not use these interfaces if at all possible. So with these caveats.... What we need to do is wire '.' and '..' to have hash values of (0,0) and (2,0), respectively, without ignoring other existing dirents with colliding hashes. (In those cases the programs will break, but they are statistically rare, and there's not much we can do in those cases anyway.) Signed-off-by:"Theodore Ts'o" <tytso@mit.edu> Signed-off-by:
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Milton D. Miller II authored
According to "initramfs buffer format -- third draft" http://lwn.net/2002/0117/a/initramfs-buffer-format.php3 "the cpio "TRAILER!!!" entry (cpio end-of-archive) is optional, but is not ignored" The kernel handling does not follow this spec. If you add null padding after an uncompressed cpio without TRAILER!!! the kernel complains "no cpio magic". In a gzipped archive one gets "junk in gzipped archive" without the TRAILER!!! This patch changes the state transitions so the kernel will follow the spec. Tested: padded uncompressed, padded compressed, unpadded compressed (error) and trailing junk in compressed (error) === I have a boot loader that knows how to load files, determine their size, and advance to the next 4-byte boundary and reports the total size of the files loaded. It doesn't understand about converting this number to some ASCII representation. With this patch I can embed the contents of a file padded with NULs with out knowing the exact size of the file with the following files: 1) file containing cpio header & file name, padded to 4 bytes 2) contents of file 3) pad file of zeros, the size at least as large as the that specified for the file. hpa points out that you should be careful with the headers, use unique inode numbers and/or add a cpio header with just TRAILER!!! to reset the inode hash table to avoid unwanted hard links. I just put this sequence as the last files loaded. Signed-off-by:
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Thayne Harbaugh authored
This patch makes gen_init_cpio more complete by adding symlink, pipe and socket support. It updates scripts/gen_initramfs_list.sh to support the new types. The patch applies to the recent mm series that already have the updated gen_init_cpio and gen_initramfs_list.sh. From: William Lee Irwin III <wli@holomorphy.com> The rest of gen_init_cpio.c seems to cast the result of strlen() to handle this situation, so this patch follows suit while killing off size_t -related printk() warnings. Signed-off-by:
William Irwin <wli@holomorphy.com> Signed-off-by:
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Randy Dunlap authored
Fix init & exit section usage, started with this diagnostic from reference_discarded.pl (make buildcheck): Error: ./drivers/misc/ibmasm/module.o .data refers to 00000058 R_386_32 .exit.text Signed-off-by:
Randy Dunlap <rddunlap@osdl.org> Signed-off-by:
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Jeff Garzik authored
Attached fixes sysfs naming of sx8 block devs to follow LANANA naming. You then get /sys/block/sx8!0, etc instead of /sys/block/sx80_0 (device names should be /dev/sx8/0 instead of /dev/sx80_0) Signed-off-by:
Jeff Garzik <jgarzik@pobox.com> Signed-off-by:
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Prasanna Meda authored
Small issue: return value missed in getdents64, but handled in getdents. Signed-Off-by:
Prasanna Meda <pmeda@akamai.com> Signed-off-by:
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Stas Sergeev authored
The attached patch fixes the CD-ROM autoclose. It is broken in recent kernels for CD-ROMs that do not properly report that the tray is opened. Now on such a drives the kernel will do one close attempt and check for the disc again. This is how it used to work in the past. Signed-off-by:
Stas Sergeev <stsp@aknet.ru> Acked-by:
Alexander Kern <alex.kern@gmx.de> Acked-by:
Jens Axboe <axboe@suse.de> Signed-off-by:
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Nathan Lynch authored
proc_create() needs to check that the name of an entry to be created does not contain a '/' character. To test, I hacked the ibmveth driver to try to call request_irq with a bogus "foo/bar" devname. The creation of the /proc/irq/1234/xxx entry silently fails, as intended. Perhaps the irq code should be made to check for the failure. Signed-off-by:
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Olaf Hering authored
A few users of request_irq pass a string with '/'. As a result, ls -l /proc/irq/*/* will fail to list these entries. Signed-off-by:
Olaf Hering <olh@suse.de> Signed-off-by:
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Olof Johansson authored
Earlier cleanup efforts of the ppc64 IOMMU code have mostly been targeted at simplifying the allocation schemes and modularising things for the various platforms. The IOMMU init functions are still a mess. This is an attempt to clean them up and make them somewhat easier to follow. The new rules are: 1. iommu_init_early_<arch> is called before any PCI/VIO init is done 2. The pcibios fixup routines will call the iommu_{bus,dev}_setup functions appropriately as devices are added. TCE space allocation has changed somewhat: * On LPARs, nothing is really different. ibm,dma-window properties are still used to determine table sizes. * On pSeries SMP-mode (non-LPAR), the full TCE space per PHB is split up in 256MB chunks, each handed out to one child bus/slot as needed. This makes current max 7 child buses per PHB, something we're currently below on all machine models I'm aware of. * Exception to the above: Pre-POWER4 machines with Python PHBs have a full GB of DMA space allocated at the PHB level, since there are no EADS-level tables on such systems. * PowerMac and Maple still work like before: all buses/slots share one table. * VIO works like before, ibm,my-dma-window is used like before. * iSeries has not been touched much at all, besides the changed unit of the it_size variable in struct iommu_table. Other things changed: * Powermac and maple PCI/IOMMU inits have been changed a bit to conform to the new init structure * pci_dma_direct.c has been renamed pci_direct_iommu.c to match pci_iommu.c (see separate patch) * Likewise, a couple of the pci direct init functions have been renamed. Signed-off-by:Olof Johansson <olof@austin.ibm.com> Acked-by:
Paul Mackerras <paulus@samba.org> Signed-off-by:
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Olof Johansson authored
This patch renames pci_dma_direct.c to pci_direct_iommu.c to comply to the naming convention of the other iommu files. This is part of the iommu cleanup, but broken out as a separate patch since for mainline, a BK rename is more appropriate. Still, we need a patch to apply for non-BK-based trees (-mm) Signed-off-by:
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Paul Mackerras authored
This patch is from Jake Moilanen <moilanen@austin.ibm.com>. Log machine check errors to error log and NVRAM. Signed-off-by:
Dave Altobelli <dalto@austin.ibm.com> Signed-off-by:
Jake Moilanen <moilanen@austin.ibm.com> Signed-off-by:
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Paul Mackerras authored
This patch is from Jake Moilanen <moilanen@austin.ibm.com>. Changed the naming conventions for head.S to more closely follow the Linux naming conventions. Signed-off-by:
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Paul Mackerras authored
This patch is from Jake Moilanen <moilanen@austin.ibm.com>. Clean-up of traps.c. Moved the machine dependent calls to a ppc_md call, and moved the pSeries specific code to ras.c. I also changed the naming convention to more closely follow the Linux standards. Signed-off-by:
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Paul Mackerras authored
This patch is from Nathan Fontenot <nfont@austin.ibm.com> originally. The PPC64 EEH code needs a small update to start using the ibm,read-slot-reset-state2 rtas call if available. The currently used ibm,read-slot-reset-state call will be going away on future machines. This patch attempts to use the newer rtas call if available and falls back the older version otherwise. This will maintain EEH slot checking capabilities on all future and current firmware levels. Signed-off-by:
Nathan Fontenot <nfont@austin.ibm.com> Signed-off-by:
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David Gibson authored
Most special purpose registers on the ppc64 have both the SPR number, and the various fields within the register defined in asm-ppc64/processor.h. So far that's not true for the performance counter control registers, MMCR0 and MMCRA. They have the SPR numbers defined, but the internal fields are defined in the oprofile code and (just a few) in traps.c where they're actually used. This patch moves all the MMCR0 and MMCRA definitions, plus the MSR performance monitor bit, MSR_PMM, into processor.h. Signed-off-by:
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Nick Piggin authored
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Rik van Riel authored
OOM kills have been observed with 70% of the pages in lowmem being in the writeback state. If we count those pages in sc->nr_scanned, the VM should throttle and wait for IO completion, instead of OOM killing. (akpm: this is how the code was designed to work - we broke it six months ago). Signed-off-by:
Rik van Riel <riel@redhat.com> Signed-off-by:
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