- 10 Sep, 2005 23 commits
-
-
Alexey Dobriyan authored
Signed-off-by:
Alexey Dobriyan <adobriyan@gmail.com> Signed-off-by:
Domen Puncer <domen@coderock.org> Signed-off-by:
Andrew Morton <akpm@osdl.org> Signed-off-by:
Linus Torvalds <torvalds@osdl.org>
-
Christophe Lucas authored
Signed-off-by:
Christophe Lucas <clucas@rotomalug.org> Signed-off-by:
-
Christophe Lucas authored
Signed-off-by:
-
Christophe Lucas authored
misc_register() can fail. Signed-off-by:
-
Adrian Bunk authored
With Nick Piggin <npiggin@suse.de> Give some things static scope. Signed-off-by:
Adrian Bunk <bunk@stusta.de> Signed-off-by:
Nick Piggin <npiggin@suse.de> Signed-off-by:
-
Paul E. McKenney authored
Update RCU documentation based on discussions and review of RCU-based tree patches. Add an introductory whatisRCU.txt file. Signed-off-by: <paulmck@us.ibm.com> Signed-off-by:
-
Arthur Othieno authored
Randy cleaned out the bulk of these stale references to the now long gone Documentation/smp.tex back in 2004. I followed this up with a few more sweeps. Somehow, these have managed to sneak back in since. I can't seem to figure out a contact point for M32R (no one listed in MAINTAINERS!), but, these patches are only but trivial. Signed-off-by:
Arthur Othieno <a.othieno@bluewin.ch> Acked-by:
Russell King <rmk+kernel@arm.linux.org.uk> Signed-off-by:
-
Siddha, Suresh B authored
Don't pull tasks from a group if that would cause the group's total load to drop below its total cpu_power (ie. cause the group to start going idle). Signed-off-by:
Suresh Siddha <suresh.b.siddha@intel.com> Signed-off-by:
Ingo Molnar <mingo@elte.hu> Signed-off-by:
-
Siddha, Suresh B authored
Jack Steiner brought this issue at my OLS talk. Take a scenario where two tasks are pinned to two HT threads in a physical package. Idle packages in the system will keep kicking migration_thread on the busy package with out any success. We will run into similar scenarios in the presence of CMP/NUMA. Signed-off-by:
-
Renaud Lienhart authored
In sys_sched_yield(), we cache current->array in the "array" variable, thus there's no need to dereference "current" again later. Signed-Off-By:
Renaud Lienhart <renaud.lienhart@free.fr> Signed-off-by:
-
Nick Piggin authored
If an idle sibling of an HT queue encounters a busy sibling, then make higher level load balancing of the non-idle variety. Performance of multiprocessor HT systems with low numbers of tasks (generally < number of virtual CPUs) can be significantly worse than the exact same workloads when running in non-HT mode. The reason is largely due to poor scheduling behaviour. This patch improves the situation, making the performance gap far less significant on one problematic test case (tbench). Signed-off-by:
-
Nick Piggin authored
During periodic load balancing, don't hold this runqueue's lock while scanning remote runqueues, which can take a non trivial amount of time especially on very large systems. Holding the runqueue lock will only help to stabilise ->nr_running, however this doesn't do much to help because tasks being woken will simply get held up on the runqueue lock, so ->nr_running would not provide a really accurate picture of runqueue load in that case anyway. What's more, ->nr_running (and possibly the cpu_load averages) of remote runqueues won't be stable anyway, so load balancing is always an inexact operation. Signed-off-by:
-
Nick Piggin authored
Similarly to the earlier change in load_balance, only lock the runqueue in load_balance_newidle if the busiest queue found has a nr_running > 1. This will reduce frequency of expensive remote runqueue lock aquisitions in the schedule() path on some workloads. Signed-off-by:
-
Ingo Molnar authored
William Weston reported unusually high scheduling latencies on his x86 HT box, on the -RT kernel. I managed to reproduce it on my HT box and the latency tracer shows the incident in action: _------=> CPU# / _-----=> irqs-off | / _----=> need-resched || / _---=> hardirq/softirq ||| / _--=> preempt-depth |||| / ||||| delay cmd pid ||||| time | caller \ / ||||| \ | / du-2803 3Dnh2 0us : __trace_start_sched_wakeup (try_to_wake_up) .............................................................. ... we are running on CPU#3, PID 2778 gets woken to CPU#1: ... .............................................................. du-2803 3Dnh2 0us : __trace_start_sched_wakeup <<...>-2778> (73 1) du-2803 3Dnh2 0us : _raw_spin_unlock (try_to_wake_up) ................................................ ... still on CPU#3, we send an IPI to CPU#1: ... ................................................ du-2803 3Dnh1 0us : resched_task (try_to_wake_up) du-2803 3Dnh1 1us : smp_send_reschedule (try_to_wake_up) du-2803 3Dnh1 1us : send_IPI_mask_bitmask (smp_send_reschedule) du-2803 3Dnh1 2us : _raw_spin_unlock_irqrestore (try_to_wake_up) ............................................... ... 1 usec later, the IPI arrives on CPU#1: ... ............................................... <idle>-0 1Dnh. 2us : smp_reschedule_interrupt (c0100c5a 0 0) So far so good, this is the normal wakeup/preemption mechanism. But here comes the scheduler anomaly on CPU#1: <idle>-0 1Dnh. 2us : preempt_schedule_irq (need_resched) <idle>-0 1Dnh. 2us : preempt_schedule_irq (need_resched) <idle>-0 1Dnh. 3us : __schedule (preempt_schedule_irq) <idle>-0 1Dnh. 3us : profile_hit (__schedule) <idle>-0 1Dnh1 3us : sched_clock (__schedule) <idle>-0 1Dnh1 4us : _raw_spin_lock_irq (__schedule) <idle>-0 1Dnh1 4us : _raw_spin_lock_irqsave (__schedule) <idle>-0 1Dnh2 5us : _raw_spin_unlock (__schedule) <idle>-0 1Dnh1 5us : preempt_schedule (__schedule) <idle>-0 1Dnh1 6us : _raw_spin_lock (__schedule) <idle>-0 1Dnh2 6us : find_next_bit (__schedule) <idle>-0 1Dnh2 6us : _raw_spin_lock (__schedule) <idle>-0 1Dnh3 7us : find_next_bit (__schedule) <idle>-0 1Dnh3 7us : find_next_bit (__schedule) <idle>-0 1Dnh3 8us : _raw_spin_unlock (__schedule) <idle>-0 1Dnh2 8us : preempt_schedule (__schedule) <idle>-0 1Dnh2 8us : find_next_bit (__schedule) <idle>-0 1Dnh2 9us : trace_stop_sched_switched (__schedule) <idle>-0 1Dnh2 9us : _raw_spin_lock (trace_stop_sched_switched) <idle>-0 1Dnh3 10us : trace_stop_sched_switched <<...>-2778> (73 8c) <idle>-0 1Dnh3 10us : _raw_spin_unlock (trace_stop_sched_switched) <idle>-0 1Dnh1 10us : _raw_spin_unlock (__schedule) <idle>-0 1Dnh. 11us : local_irq_enable_noresched (preempt_schedule_irq) <idle>-0 1Dnh. 11us < (0) we didnt pick up pid 2778! It only gets scheduled much later: <...>-2778 1Dnh2 412us : __switch_to (__schedule) <...>-2778 1Dnh2 413us : __schedule <<idle>-0> (8c 73) <...>-2778 1Dnh2 413us : _raw_spin_unlock (__schedule) <...>-2778 1Dnh1 413us : trace_stop_sched_switched (__schedule) <...>-2778 1Dnh1 414us : _raw_spin_lock (trace_stop_sched_switched) <...>-2778 1Dnh2 414us : trace_stop_sched_switched <<...>-2778> (73 1) <...>-2778 1Dnh2 414us : _raw_spin_unlock (trace_stop_sched_switched) <...>-2778 1Dnh1 415us : trace_stop_sched_switched (__schedule) the reason for this anomaly is the following code in dependent_sleeper(): /* * If a user task with lower static priority than the * running task on the SMT sibling is trying to schedule, * delay it till there is proportionately less timeslice * left of the sibling task to prevent a lower priority * task from using an unfair proportion of the * physical cpu's resources. -ck */ [...] if (((smt_curr->time_slice * (100 - sd->per_cpu_gain) / 100) > task_timeslice(p))) ret = 1; Note that in contrast to the comment above, we dont actually do the check based on static priority, we do the check based on timeslices. But timeslices go up and down, and even highprio tasks can randomly have very low timeslices (just before their next refill) and can thus be judged as 'lowprio' by the above piece of code. This condition is clearly buggy. The correct test is to check for static_prio _and_ to check for the preemption priority. Even on different static priority levels, a higher-prio interactive task should not be delayed due to a higher-static-prio CPU hog. There is a symmetric bug in the 'kick SMT sibling' code of this function as well, which can be solved in a similar way. The patch below (against the current scheduler queue in -mm) fixes both bugs. I have build and boot-tested this on x86 SMT, and nice +20 tasks still get properly throttled - so the dependent-sleeper logic is still in action. btw., these bugs pessimised the SMT scheduler because the 'delay wakeup' property was applied too liberally, so this fix is likely a throughput improvement as well. I separated out a smt_slice() function to make the code easier to read. Signed-off-by: -
Ingo Molnar authored
This patch implements a task state bit (TASK_NONINTERACTIVE), which can be used by blocking points to mark the task's wait as "non-interactive". This does not mean the task will be considered a CPU-hog - the wait will simply not have an effect on the waiting task's priority - positive or negative alike. Right now only pipe_wait() will make use of it, because it's a common source of not-so-interactive waits (kernel compilation jobs, etc.). Signed-off-by:
-
Ingo Molnar authored
whitespace cleanups. Signed-off-by:
-
M.Baris Demiray authored
Add relevant checks into find_idlest_group() and find_idlest_cpu() to make them return only the groups that have allowed CPUs and allowed CPUs respectively. Signed-off-by:
M.Baris Demiray <baris@labristeknoloji.com> Signed-off-by:
Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by:
-
Con Kolivas authored
The hyperthread aware nice handling currently puts to sleep any non real time task when a real time task is running on its sibling cpu. This can lead to prolonged starvation by having the non real time task pegged to the cpu with load balancing not pulling that task away. Currently we force lower priority hyperthread tasks to run a percentage of time difference based on timeslice differences which is meaningless when comparing real time tasks to SCHED_NORMAL tasks. We can allow non real time tasks to run with real time tasks on the sibling up to per_cpu_gain% if we use jiffies as a counter. Cleanups and micro-optimisations to the relevant code section should make it more understandable as well. Signed-off-by:
Con Kolivas <kernel@kolivas.org> Acked-by:
-
Paul Fulghum authored
Add ability to clear statistics. Signed-off-by:
Paul Fulghum <paulkf@microgate.com> Signed-off-by:
-
Paul Jackson authored
The cpusets-formalize-intermediate-gfp_kernel-containment patch has a deadlock problem. This patch was part of a set of four patches to make more extensive use of the cpuset 'mem_exclusive' attribute to manage kernel GFP_KERNEL memory allocations and to constrain the out-of-memory (oom) killer. A task that is changing cpusets in particular ways on a system when it is very short of free memory could double trip over the global cpuset_sem semaphore (get the lock and then deadlock trying to get it again). The second attempt to get cpuset_sem would be in the routine cpuset_zone_allowed(). This was discovered by code inspection. I can not reproduce the problem except with an artifically hacked kernel and a specialized stress test. In real life you cannot hit this unless you are manipulating cpusets, and are very unlikely to hit it unless you are rapidly modifying cpusets on a memory tight system. Even then it would be a rare occurence. If you did hit it, the task double tripping over cpuset_sem would deadlock in the kernel, and any other task also trying to manipulate cpusets would deadlock there too, on cpuset_sem. Your batch manager would be wedged solid (if it was cpuset savvy), but classic Unix shells and utilities would work well enough to reboot the system. The unusual condition that led to this bug is that unlike most semaphores, cpuset_sem _can_ be acquired while in the page allocation code, when __alloc_pages() calls cpuset_zone_allowed. So it easy to mistakenly perform the following sequence: 1) task makes system call to alter a cpuset 2) take cpuset_sem 3) try to allocate memory 4) memory allocator, via cpuset_zone_allowed, trys to take cpuset_sem 5) deadlock The reason that this is not a serious bug for most users is that almost all calls to allocate memory don't require taking cpuset_sem. Only some code paths off the beaten track require taking cpuset_sem -- which is good. Taking a global semaphore on the main code path for allocating memory would not scale well. This patch fixes this deadlock by wrapping the up() and down() calls on cpuset_sem in kernel/cpuset.c with code that tracks the nesting depth of the current task on that semaphore, and only does the real down() if the task doesn't hold the lock already, and only does the real up() if the nesting depth (number of unmatched downs) is exactly one. The previous required use of refresh_mems(), anytime that the cpuset_sem semaphore was acquired and the code executed while holding that semaphore might try to allocate memory, is no longer required. Two refresh_mems() calls were removed thanks to this. This is a good change, as failing to get all the necessary refresh_mems() calls placed was a primary source of bugs in this cpuset code. The only remaining call to refresh_mems() is made while doing a memory allocation, if certain task memory placement data needs to be updated from its cpuset, due to the cpuset having been changed behind the tasks back. Signed-off-by:
Paul Jackson <pj@sgi.com> Signed-off-by:
-
Ingo Molnar authored
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:
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:
-
Alan Cox authored
pcibus_to_cpumask expands into more than just an initialiser so gcc moans about code before variable declarations. Signed-off-by:
Alan Cox <alan@redhat.com> Signed-off-by:
-
Andrew Morton authored
*** Warning: "bit_spin_lock" [fs/ntfs/ntfs.ko] undefined! *** Warning: "bit_spin_unlock" [fs/ntfs/ntfs.ko] undefined! Cc: Anton Altaparmakov <aia21@cantab.net> Signed-off-by:
-
- 09 Sep, 2005 17 commits
-
-
NeilBrown authored
This shouldn't be a BUG. We should cope. Signed-off-by:
Neil Brown <neilb@suse.de> Signed-off-by:
-
NeilBrown authored
If you try to assemble an array with too many missing devices, raid10 will now reject the attempt, instead of allowing it. Also check when hot-adding a drive and refuse the hot-add if the array is beyond hope. Signed-off-by:
-
NeilBrown authored
There was another case where sb_size wasn't being set, so instead do the sensible thing and set if when filling in the content of a superblock. That ensures that whenever we write a superblock, the sb_size MUST be set. Signed-off-by:
-
NeilBrown authored
[PATCH] md: make sure the new 'sb_size' is set properly device added without pre-existing superblock. There are two ways to add devices to an md/raid array. It can have superblock written to it, and then given to the md driver, which will read the superblock (the new way) or md can be told (through SET_ARRAY_INFO) the shape of the array, and the told about individual drives, and md will create the required superblock (the old way). The newly introduced sb_size was only set for drives being added the new way, not the old ways. Oops :-( Signed-off-by:
-
NeilBrown authored
Just like failed drives have (F), so spare drives now have (S). Signed-off-by:
-
NeilBrown authored
Leave it unchanged if the original (0.90) is used, incase it might be a compatability problem. Signed-off-by:
-
NeilBrown authored
Doh. I want the physical hard-sector-size, not the current block size... Signed-off-by:
-
NeilBrown authored
On reflection, a better default location for hot-adding bitmaps with version-1 superblocks is immediately after the superblock. There might not be much room there, but there is usually atleast 3k, and that is a good start. Signed-off-by:
-
NeilBrown authored
The bitmap code used to have two daemons, so there is some 'common' start/stop code. But now there is only one, so the common code is just noise. This patch tidies this up somewhat. Signed-off-by:
Neil Brown <neilb@cse.unsw.edu.au> Signed-off-by:
-
NeilBrown authored
mddev->bitmap gets clearred before the writeback daemon is stopped. So the write_back daemon needs to be careful not to dereference the 'bitmap' if it is NULL. Signed-off-by:
-
NeilBrown authored
Switch MD to use the kthread infrastructure, to simplify the code and get rid of tasklist_lock abuse in md_unregister_thread. Also don't flush signals in md_thread, as the called thread will always do that. Signed-off-by:
Christoph Hellwig <hch@lst.de> Signed-off-by:
-
NeilBrown authored
This is a direct port of the raid5 patch. Signed-off-by:
-
NeilBrown authored
Most awkward part of this is delaying write requests until bitmap updates have been flushed. To achieve this, we have a sequence number (seq_flush) which is incremented each time the raid5 is unplugged. If the raid thread notices that this has changed, it flushes bitmap changes, and assigned the value of seq_flush to seq_write. When a write request arrives, it is given the number from seq_write, and that write request may not complete until seq_flush is larger than the saved seq number. We have a new queue for storing stripes which are waiting for a bitmap flush and an extra flag for stripes to record if the write was 'degraded' and so should not clear the a bit in the bitmap. Signed-off-by:
-
NeilBrown authored
version-1 superblocks are not (normally) 4K long, and can be of variable size. Writing the full 4K can cause corruption (but only in non-default configurations). With this patch the super-block-flavour can choose a size to read, and set a size to write based on what it finds. Signed-off-by:
-
NeilBrown authored
These inlines haven't been used for ages, they should go. Signed-off-by:
-
NeilBrown authored
read_sb_page() assumed that if sync_page_io fails, the device would be marked faultly. However it isn't. So in the face of error, read_sb_page would loop forever. Redo the logic so that this cannot happen. Signed-off-by:
-
NeilBrown authored
As this is used to flag an internal bitmap. Also, introduce symbolic names for feature bits. Signed-off-by:
-
