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* block: blk_max_pfn is somtimes wrongVasily Tarasov2007-03-271-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | There is a small problem in handling page bounce. At the moment blk_max_pfn equals max_pfn, which is in fact not maximum possible _number_ of a page frame, but the _amount_ of page frames. For example for the 32bit x86 node with 4Gb RAM, max_pfn = 0x100000, but not 0xFFFF. request_queue structure has a member q->bounce_pfn and queue needs bounce pages for the pages _above_ this limit. This routine is handled by blk_queue_bounce(), where the following check is produced: if (q->bounce_pfn >= blk_max_pfn) return; Assume, that a driver has set q->bounce_pfn to 0xFFFF, but blk_max_pfn equals 0x10000. In such situation the check above fails and for each bio we always fall down for iterating over pages tied to the bio. I want to notice, that for quite a big range of device drivers (ide, md, ...) such problem doesn't happen because they use BLK_BOUNCE_ANY for bounce_pfn. BLK_BOUNCE_ANY is defined as blk_max_pfn << PAGE_SHIFT, and then the check above doesn't fail. But for other drivers, which obtain reuired value from drivers, it fails. For example sata_nv uses ATA_DMA_MASK or dev->dma_mask. I propose to use (max_pfn - 1) for blk_max_pfn. And the same for blk_max_low_pfn. The patch also cleanses some checks related with bounce_pfn. Signed-off-by: Vasily Tarasov <vtaras@openvz.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] md: fix various bugs with aligned reads in RAID5Neil Brown2007-02-091-1/+1
| | | | | | | | | | | | | | | | | | | | | | | | | It is possible for raid5 to be sent a bio that is too big for an underlying device. So if it is a READ that we pass stright down to a device, it will fail and confuse RAID5. So in 'chunk_aligned_read' we check that the bio fits within the parameters for the target device and if it doesn't fit, fall back on reading through the stripe cache and making lots of one-page requests. Note that this is the earliest time we can check against the device because earlier we don't have a lock on the device, so it could change underneath us. Also, the code for handling a retry through the cache when a read fails has not been tested and was badly broken. This patch fixes that code. Signed-off-by: Neil Brown <neilb@suse.de> Cc: "Kai" <epimetreus@fastmail.fm> Cc: <stable@suse.de> Cc: <org@suse.de> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
* [PATCH] fix kernel-doc warnings in 2.6.20-rc1Randy Dunlap2006-12-221-0/+1
| | | | | | | | Fix kernel-doc warnings in 2.6.20-rc1. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] Fixup blk_rq_unmap_user() APIJens Axboe2006-12-191-12/+16
| | | | | | | | | The blk_rq_unmap_user() API is not very nice. It expects the caller to know that rq->bio has to be reset to the original bio, and it will silently do nothing if that is not done. Instead make it explicit that we need to pass in the first bio, by expecting a bio argument. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] __blk_rq_unmap_user() fails to return errorJens Axboe2006-12-191-2/+7
| | | | | | | If the bio is user copied, the copy back could return -EFAULT. Make sure we return any error seen during unmapping. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] __blk_rq_map_user() doesn't need to grab the queue_lockJens Axboe2006-12-191-9/+0
| | | | | | | It was for driver private back_merge_fn hooks, but they don't exist anymore. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] Remove queue merging hooksJens Axboe2006-12-191-9/+6
| | | | | | | | We have full flexibility of merging parameters now, so we can remove the hooks that define back/front/request merge strategies. Nobody is using them anymore. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] ->nr_sectors and ->hard_nr_sectors are not used for BLOCK_PC requestsJens Axboe2006-12-191-4/+2
| | | | | | | It's a file system thing, for block requests the only size used in the io paths is ->data_len as it is in bytes, not sectors. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] Propagate down request sync flagJens Axboe2006-12-131-8/+20
| | | | | | | | We need to do this, otherwise the io schedulers don't get access to the sync flag. Then they cannot tell the difference between a regular write and an O_DIRECT write, which can cause a performance loss. Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] remove blk_queue_activity_fnBoaz Harrosh2006-12-121-12/+0
| | | | | | | | | | | | | | | | | | While working on bidi support at struct request level I have found that blk_queue_activity_fn is actually never used. The only user is in ide-probe.c with this code: /* enable led activity for disk drives only */ if (drive->media == ide_disk && hwif->led_act) blk_queue_activity_fn(q, hwif->led_act, drive); And led_act is never initialized anywhere. (Looking back at older kernels it was used in the PPC arch, but was removed around 2.6.18) Unless it is all for future use off course. (this patch is against linux-2.6-block.git as off 2006/12/4) Signed-off-by: Boaz Harrosh <bharrosh@panasas.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] io-accounting: read accountingAndrew Morton2006-12-101-2/+5
| | | | | | | | | | | | | | Wire up read accounting for block devices, within submit_bio(). Cc: Jay Lan <jlan@sgi.com> Cc: Shailabh Nagar <nagar@watson.ibm.com> Cc: Balbir Singh <balbir@in.ibm.com> Cc: Chris Sturtivant <csturtiv@sgi.com> Cc: Tony Ernst <tee@sgi.com> Cc: Guillaume Thouvenin <guillaume.thouvenin@bull.net> Cc: David Wright <daw@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] fault-injection capability for disk IOAkinobu Mita2006-12-081-0/+40
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | This patch provides fault-injection capability for disk IO. Boot option: fail_make_request=<probability>,<interval>,<space>,<times> <interval> -- specifies the interval of failures. <probability> -- specifies how often it should fail in percent. <space> -- specifies the size of free space where disk IO can be issued safely in bytes. <times> -- specifies how many times failures may happen at most. Debugfs: /debug/fail_make_request/interval /debug/fail_make_request/probability /debug/fail_make_request/specifies /debug/fail_make_request/times Example: fail_make_request=10,100,0,-1 echo 1 > /sys/blocks/hda/hda1/make-it-fail generic_make_request() on /dev/hda1 fails once per 10 times. Cc: Jens Axboe <axboe@suse.de> Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] hotplug CPU: clean up hotcpu_notifier() useIngo Molnar2006-12-071-4/+0
| | | | | | | | | | | | | | | | | | There was lots of #ifdef noise in the kernel due to hotcpu_notifier(fn, prio) not correctly marking 'fn' as used in the !HOTPLUG_CPU case, and thus generating compiler warnings of unused symbols, hence forcing people to add #ifdefs. the compiler can skip truly unused functions just fine: text data bss dec hex filename 1624412 728710 3674856 6027978 5bfaca vmlinux.before 1624412 728710 3674856 6027978 5bfaca vmlinux.after [akpm@osdl.org: topology.c fix] Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] slab: remove kmem_cache_tChristoph Lameter2006-12-071-3/+3
| | | | | | | | | | | | | | | | | | | | | | | | | | | | Replace all uses of kmem_cache_t with struct kmem_cache. The patch was generated using the following script: #!/bin/sh # # Replace one string by another in all the kernel sources. # set -e for file in `find * -name "*.c" -o -name "*.h"|xargs grep -l $1`; do quilt add $file sed -e "1,\$s/$1/$2/g" $file >/tmp/$$ mv /tmp/$$ $file quilt refresh done The script was run like this sh replace kmem_cache_t "struct kmem_cache" Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Merge branch 'master' of ↵David Howells2006-12-051-40/+126
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux-2.6 Conflicts: drivers/infiniband/core/iwcm.c drivers/net/chelsio/cxgb2.c drivers/net/wireless/bcm43xx/bcm43xx_main.c drivers/net/wireless/prism54/islpci_eth.c drivers/usb/core/hub.h drivers/usb/input/hid-core.c net/core/netpoll.c Fix up merge failures with Linus's head and fix new compilation failures. Signed-Off-By: David Howells <dhowells@redhat.com>
| * [PATCH] block: support larger block pc requestsMike Christie2006-12-011-40/+126
| | | | | | | | | | | | | | | | This patch modifies blk_rq_map/unmap_user() and the cdrom and scsi_ioctl.c users so that it supports requests larger than bio by chaining them together. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* | WorkStruct: Pass the work_struct pointer instead of context dataDavid Howells2006-11-221-4/+4
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Pass the work_struct pointer to the work function rather than context data. The work function can use container_of() to work out the data. For the cases where the container of the work_struct may go away the moment the pending bit is cleared, it is made possible to defer the release of the structure by deferring the clearing of the pending bit. To make this work, an extra flag is introduced into the management side of the work_struct. This governs auto-release of the structure upon execution. Ordinarily, the work queue executor would release the work_struct for further scheduling or deallocation by clearing the pending bit prior to jumping to the work function. This means that, unless the driver makes some guarantee itself that the work_struct won't go away, the work function may not access anything else in the work_struct or its container lest they be deallocated.. This is a problem if the auxiliary data is taken away (as done by the last patch). However, if the pending bit is *not* cleared before jumping to the work function, then the work function *may* access the work_struct and its container with no problems. But then the work function must itself release the work_struct by calling work_release(). In most cases, automatic release is fine, so this is the default. Special initiators exist for the non-auto-release case (ending in _NAR). Signed-Off-By: David Howells <dhowells@redhat.com>
* [PATCH] tidy "md: check bio address after mapping through partitions"Andrew Morton2006-11-031-4/+5
| | | | | | | | | Neil's xterms are too wide. Cc: Neil Brown <neilb@cse.unsw.edu.au> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] md: check bio address after mapping through partitions.NeilBrown2006-10-311-4/+20
| | | | | | | | | | | | | | | Partitions are not limited to live within a device. So we should range check after partition mapping. Note that 'maxsector' was being used for two different things. I have split off the second usage into 'old_sector' so that maxsector can be still be used for it's primary usage later in the function. Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Neil Brown <neilb@suse.de> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] separate bdi congestion functions from queue congestion functionsAndrew Morton2006-10-201-71/+0
| | | | | | | | | | | | | | | | | | | Separate out the concept of "queue congestion" from "backing-dev congestion". Congestion is a backing-dev concept, not a queue concept. The blk_* congestion functions are retained, as wrappers around the core backing-dev congestion functions. This proper layering is needed so that NFS can cleanly use the congestion functions, and so that CONFIG_BLOCK=n actually links. Cc: "Thomas Maier" <balagi@justmail.de> Cc: "Jens Axboe" <jens.axboe@oracle.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> Cc: David Howells <dhowells@redhat.com> Cc: Peter Osterlund <petero2@telia.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] export clear_queue_congested and set_queue_congestedThomas Maier2006-10-201-10/+10
| | | | | | | | | | | | | | | | Export the clear_queue_congested() and set_queue_congested() functions located in ll_rw_blk.c The functions are renamed to blk_clear_queue_congested() and blk_set_queue_congested(). (needed in the pktcdvd driver's bio write congestion control) Signed-off-by: Thomas Maier <balagi@justmail.de> Cc: Peter Osterlund <petero2@telia.com> Cc: Jens Axboe <jens.axboe@oracle.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] helper function for retrieving scsi_cmd given host based block layer tagDavid C Somayajulu2006-10-041-6/+1
| | | | | | | | | | This was necessitated by the need for a function to get back to a scsi_cmnd, when an hba the posts its (corresponding) completion interrupt with a block layer tag as its reference. Signed-off-by: Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: David Somayajulu <david.somayajulu@qlogic.com> Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
* [PATCH] blk_queue_start_tag() shared map race fixJens Axboe2006-09-301-4/+9
| | | | | | | | | | | If we share the tag map between two or more queues, then we cannot use __set_bit() to set the bit. In fact we need to make sure we atomically acquire this tag, so loop using test_and_set_bit() to protect from that. Noticed by Mike Christie <michaelc@cs.wisc.edu> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* [PATCH] exit_io_context: don't disable irqsOleg Nesterov2006-09-301-5/+2
| | | | | | | | | | | | | We don't need to disable irqs to clear current->io_context, it is protected by ->alloc_lock. Even IF it was possible to submit I/O from IRQ on behalf of current this irq_disable() can't help: current_io_context() will re-instantiate ->io_context after irq_enable(). We don't need task_lock() or local_irq_disable() to clear ioc->task. This can't prevent other CPUs from playing with our io_context anyway. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Jens Axboe <axboe@kernel.dk>
* [PATCH] Allow file systems to differentiate between data and meta readsJens Axboe2006-09-301-0/+2
| | | | | | | We can use this information for making more intelligent priority decisions, and it will also be useful for blktrace. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] ll_rw_blk: allow more flexibility for read_ahead_kb storeJens Axboe2006-09-301-3/+0
| | | | | | | | | | | It can make sense to set read-ahead larger than a single request. We should not be enforcing such policy on the user. Additionally, using the BLKRASET ioctl doesn't impose such a restriction. So additionally we now expose identical behaviour through the two. Issue also reported by Anton <cbou@mail.ru> Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Add blk_start_queueing() helperJens Axboe2006-09-301-5/+20
| | | | | | | | | | CFQ implements this on its own now, but it's really block layer knowledge. Tells a device queue to start dispatching requests to the driver, taking care to unplug if needed. Also fixes the issue where as/cfq will invoke a stopped queue, which we really don't want. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Make sure all block/io scheduler setups are node awareJens Axboe2006-09-301-6/+7
| | | | | | | Some were kmalloc_node(), some were still kmalloc(). Change them all to kmalloc_node(). Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Audit block layer inlinesJens Axboe2006-09-301-4/+4
| | | | | | | Kill a few inlines that bring in too much code to more than one location Shrinks kernel text by about 300 bytes on 32-bit x86. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] cfq-iosched: kill cfq_exit_lockJens Axboe2006-09-301-1/+1
| | | | | | | | | | | | | | | | | | | | | cfq_exit_lock is protecting two things now: - The per-ioc rbtree of cfq_io_contexts - The per-cfqd linked list of cfq_io_contexts The per-cfqd linked list can be protected by the queue lock, as it is (by definition) per cfqd as the queue lock is. The per-ioc rbtree is mainly used and updated by the process itself only. The only outside use is the io priority changing. If we move the priority changing to not browsing the rbtree, we can remove any locking from the rbtree updates and lookup completely. Let the sys_ioprio syscall just mark processes as having the iopriority changed and lazily update the private cfq io contexts the next time io is queued, and we can remove this locking as well. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] ll_rw_blk: cleanup __make_request()Jens Axboe2006-09-301-15/+7
| | | | | | | | - Don't assign variables that are only used once. - Kill spin_lock() prefetching, it's opportunistic at best. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Drop useless bio passing in may_queue/set_request APIJens Axboe2006-09-301-5/+4
| | | | | | It's not needed for anything, so kill the bio passing. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Remove ->rq_status from struct requestJens Axboe2006-09-301-3/+0
| | | | | | | | | | | After Christophs SCSI change, the only usage left is RQ_ACTIVE and RQ_INACTIVE. The block layer sets RQ_INACTIVE right before freeing the request, so any check for RQ_INACTIVE in a driver is a bug and indicates use-after-free. So kill/clean the remaining users, straight forward. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Remove struct request_list from struct requestJens Axboe2006-09-301-8/+2
| | | | | | | | It is always identical to &q->rq, and we only use it for detecting whether this request came out of our mempool or not. So replace it with an additional ->flags bit flag. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Remove ->waiting member from struct requestJens Axboe2006-09-301-7/+6
| | | | | | | | As the comments indicates in blkdev.h, we can fold it into ->end_io_data usage as that is really what ->waiting is. Fixup the users of blk_end_sync_rq(). Signed-off-by: Jens Axboe <axboe@kernel.dk>
* [PATCH] elevator: abstract out the rbtree sort handlingJens Axboe2006-09-301-3/+4
| | | | | | | | | | | | The rbtree sort/lookup/reposition logic is mostly duplicated in cfq/deadline/as, so move it to the elevator core. The io schedulers still provide the actual rb root, as we don't want to impose any sort of specific handling on the schedulers. Introduce the helpers and rb_node in struct request to help migrate the IO schedulers. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] elevator: move the backmerging logic into the elevator coreJens Axboe2006-09-301-0/+2
| | | | | | | | | | | Right now, every IO scheduler implements its own backmerging (except for noop, which does no merging). That results in duplicated code for essentially the same operation, which is never a good thing. This patch moves the backmerging out of the io schedulers and into the elevator core. We save 1.6kb of text and as a bonus get backmerging for noop as well. Win-win! Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Split struct request ->flags into two partsJens Axboe2006-09-301-66/+35
| | | | | | | | | | Right now ->flags is a bit of a mess: some are request types, and others are just modifiers. Clean this up by splitting it into ->cmd_type and ->cmd_flags. This allows introduction of generic Linux block message types, useful for sending generic Linux commands to block devices. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] ifdef blktrace debugging fieldsAlexey Dobriyan2006-09-291-2/+1
| | | | | | | Signed-off-by: Alexey Dobriyan <adobriyan@gmail.com> Acked-by: Jens Axboe <axboe@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Merge mulgrave-w:git/linux-2.6James Bottomley2006-09-231-0/+12
|\ | | | | | | | | | | | | | | Conflicts: include/linux/blkdev.h Trivial merge to incorporate tag prototypes.
| * Add a real API for dealing with blk_congestion_wait()Trond Myklebust2006-09-221-0/+12
| | | | | | | | Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
* | [SCSI] block: add support for shared tag mapsJames Bottomley2006-08-311-21/+88
|/ | | | | | | | | | The current block queue implementation already contains most of the machinery for shared tag maps. The only remaining pieces are a way to allocate and destroy a tag map independently of the queues (so that the maps can be managed on the life cycle of the overseeing entity) Acked-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>
* [PATCH] Fix current_io_context() vs set_task_ioprio() raceOleg Nesterov2006-08-211-0/+2
| | | | | | | | | | | I know nothing about io scheduler, but I suspect set_task_ioprio() is not safe. current_io_context() initializes "struct io_context", then sets ->io_context. set_task_ioprio() running on another cpu may see the changes out of order, so ->set_ioprio(ioc) may use io_context which was not initialized properly. Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru> Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] Only the first two bits in bio->bi_rw and rq->flags matchJens Axboe2006-07-061-2/+2
| | | | | | | Not three, as assumed. This causes the barrier bit to be needlessly set for some IO. Signed-off-by: Jens Axboe <axboe@suse.de>
* [PATCH] lockdep: annotate on-stack completionsIngo Molnar2006-07-031-1/+1
| | | | | | | | | | | | lockdep needs to have the waitqueue lock initialized for on-stack waitqueues implicitly initialized by DECLARE_COMPLETION(). Annotate on-stack completions accordingly. Has no effect on non-lockdep kernels. Signed-off-by: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* Merge git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivialLinus Torvalds2006-06-301-1/+0
|\ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | * git://git.kernel.org/pub/scm/linux/kernel/git/bunk/trivial: Remove obsolete #include <linux/config.h> remove obsolete swsusp_encrypt arch/arm26/Kconfig typos Documentation/IPMI typos Kconfig: Typos in net/sched/Kconfig v9fs: do not include linux/version.h Documentation/DocBook/mtdnand.tmpl: typo fixes typo fixes: specfic -> specific typo fixes in Documentation/networking/pktgen.txt typo fixes: occuring -> occurring typo fixes: infomation -> information typo fixes: disadvantadge -> disadvantage typo fixes: aquire -> acquire typo fixes: mecanism -> mechanism typo fixes: bandwith -> bandwidth fix a typo in the RTC_CLASS help text smb is no longer maintained Manually merged trivial conflict in arch/um/kernel/vmlinux.lds.S
| * Remove obsolete #include <linux/config.h>Jörn Engel2006-06-301-1/+0
| | | | | | | | | | Signed-off-by: Jörn Engel <joern@wohnheim.fh-wedel.de> Signed-off-by: Adrian Bunk <bunk@stusta.de>
* | [PATCH] Light weight event countersChristoph Lameter2006-06-301-2/+2
|/ | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | The remaining counters in page_state after the zoned VM counter patches have been applied are all just for show in /proc/vmstat. They have no essential function for the VM. We use a simple increment of per cpu variables. In order to avoid the most severe races we disable preempt. Preempt does not prevent the race between an increment and an interrupt handler incrementing the same statistics counter. However, that race is exceedingly rare, we may only loose one increment or so and there is no requirement (at least not in kernel) that the vm event counters have to be accurate. In the non preempt case this results in a simple increment for each counter. For many architectures this will be reduced by the compiler to a single instruction. This single instruction is atomic for i386 and x86_64. And therefore even the rare race condition in an interrupt is avoided for both architectures in most cases. The patchset also adds an off switch for embedded systems that allows a building of linux kernels without these counters. The implementation of these counters is through inline code that hopefully results in only a single instruction increment instruction being emitted (i386, x86_64) or in the increment being hidden though instruction concurrency (EPIC architectures such as ia64 can get that done). Benefits: - VM event counter operations usually reduce to a single inline instruction on i386 and x86_64. - No interrupt disable, only preempt disable for the preempt case. Preempt disable can also be avoided by moving the counter into a spinlock. - Handling is similar to zoned VM counters. - Simple and easily extendable. - Can be omitted to reduce memory use for embedded use. References: RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=113512330605497&w=2 RFC http://marc.theaimsgroup.com/?l=linux-kernel&m=114988082814934&w=2 local_t http://marc.theaimsgroup.com/?l=linux-kernel&m=114991748606690&w=2 V2 http://marc.theaimsgroup.com/?t=115014808400007&r=1&w=2 V3 http://marc.theaimsgroup.com/?l=linux-kernel&m=115024767022346&w=2 V4 http://marc.theaimsgroup.com/?l=linux-kernel&m=115047968808926&w=2 Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cpu hotplug: use hotplug version of cpu notifier in appropriate placesChandra Seetharaman2006-06-271-3/+1
| | | | | | | | | | Make use the of newly defined hotplug version of cpu_notifier functionality wherever appropriate. Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* [PATCH] cpu hotplug: revert initdata patch submitted for 2.6.17Chandra Seetharaman2006-06-271-1/+1
| | | | | | | | | This patch reverts notifier_block changes made in 2.6.17 Signed-off-by: Chandra Seetharaman <sekharan@us.ibm.com> Cc: Ashok Raj <ashok.raj@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
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