- 07 May, 2007 40 commits
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Christoph Lameter authored
If we add a new flag so that we can distinguish between the first page and the tail pages then we can avoid to use page->private in the first page. page->private == page for the first page, so there is no real information in there. Freeing up page->private makes the use of compound pages more transparent. They become more usable like real pages. Right now we have to be careful f.e. if we are going beyond PAGE_SIZE allocations in the slab on i386 because we can then no longer use the private field. This is one of the issues that cause us not to support debugging for page size slabs in SLAB. Having page->private available for SLUB would allow more meta information in the page struct. I can probably avoid the 16 bit ints that I have in there right now. Also if page->private is available then a compound page may be equipped with buffer heads. This may free up the way for filesystems to support larger blocks than page size. We add PageTail as an alias of PageReclaim. Compound pages cannot currently be reclaimed. Because of the alias one needs to check PageCompound first. The RFC for the this approach was discussed at http://marc.info/?t=117574302800001&r=1&w=2 [nacc@us.ibm.com: fix hugetlbfs] Signed-off-by:
Christoph Lameter <clameter@sgi.com> Signed-off-by:
Nishanth Aravamudan <nacc@us.ibm.com> Signed-off-by:
Andrew Morton <akpm@linux-foundation.org> Signed-off-by:
Linus Torvalds <torvalds@linux-foundation.org>
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Christoph Lameter authored
PowerPC uses the slab allocator to manage the lowest level of the page table. In high cpu configurations we also use the page struct to split the page table lock. Disallow the selection of SLUB for that case. Signed-off-by:
Benjamin Herrenschmidt <benh@kernel.crashing.org> Signed-off-by:
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Christoph Lameter authored
Makes SLUB behave like SLAB in this area to avoid issues.... Throw a stack dump to alert people. At some point the behavior should be switched back. NULL is no memory as far as I can tell and if the use asked for 0 bytes then he need to get no memory. Signed-off-by:
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Christoph Lameter authored
Structures may contain u64 items on 32 bit platforms that are only able to address 64 bit items on 64 bit boundaries. Change the mininum alignment of slabs to conform to those expectations. ARCH_KMALLOC_MINALIGN must be changed for good since a variety of structure are mixed in the general slabs. ARCH_SLAB_MINALIGN is changed because currently there is no consistent specification of object alignment. We may have that in the future when the KMEM_CACHE and related macros are used to generate slabs. These pass the alignment of the structure generated by the compiler to the slab. With KMEM_CACHE etc we could align structures that do not contain 64 bit values to 32 bit boundaries potentially saving some memory. Signed-off-by:
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Christoph Lameter authored
This is a new slab allocator which was motivated by the complexity of the existing code in mm/slab.c. It attempts to address a variety of concerns with the existing implementation. A. Management of object queues A particular concern was the complex management of the numerous object queues in SLAB. SLUB has no such queues. Instead we dedicate a slab for each allocating CPU and use objects from a slab directly instead of queueing them up. B. Storage overhead of object queues SLAB Object queues exist per node, per CPU. The alien cache queue even has a queue array that contain a queue for each processor on each node. For very large systems the number of queues and the number of objects that may be caught in those queues grows exponentially. On our systems with 1k nodes / processors we have several gigabytes just tied up for storing references to objects for those queues This does not include the objects that could be on those queues. One fears that the whole memory of the machine could one day be consumed by those queues. C. SLAB meta data overhead SLAB has overhead at the beginning of each slab. This means that data cannot be naturally aligned at the beginning of a slab block. SLUB keeps all meta data in the corresponding page_struct. Objects can be naturally aligned in the slab. F.e. a 128 byte object will be aligned at 128 byte boundaries and can fit tightly into a 4k page with no bytes left over. SLAB cannot do this. D. SLAB has a complex cache reaper SLUB does not need a cache reaper for UP systems. On SMP systems the per CPU slab may be pushed back into partial list but that operation is simple and does not require an iteration over a list of objects. SLAB expires per CPU, shared and alien object queues during cache reaping which may cause strange hold offs. E. SLAB has complex NUMA policy layer support SLUB pushes NUMA policy handling into the page allocator. This means that allocation is coarser (SLUB does interleave on a page level) but that situation was also present before 2.6.13. SLABs application of policies to individual slab objects allocated in SLAB is certainly a performance concern due to the frequent references to memory policies which may lead a sequence of objects to come from one node after another. SLUB will get a slab full of objects from one node and then will switch to the next. F. Reduction of the size of partial slab lists SLAB has per node partial lists. This means that over time a large number of partial slabs may accumulate on those lists. These can only be reused if allocator occur on specific nodes. SLUB has a global pool of partial slabs and will consume slabs from that pool to decrease fragmentation. G. Tunables SLAB has sophisticated tuning abilities for each slab cache. One can manipulate the queue sizes in detail. However, filling the queues still requires the uses of the spin lock to check out slabs. SLUB has a global parameter (min_slab_order) for tuning. Increasing the minimum slab order can decrease the locking overhead. The bigger the slab order the less motions of pages between per CPU and partial lists occur and the better SLUB will be scaling. G. Slab merging We often have slab caches with similar parameters. SLUB detects those on boot up and merges them into the corresponding general caches. This leads to more effective memory use. About 50% of all caches can be eliminated through slab merging. This will also decrease slab fragmentation because partial allocated slabs can be filled up again. Slab merging can be switched off by specifying slub_nomerge on boot up. Note that merging can expose heretofore unknown bugs in the kernel because corrupted objects may now be placed differently and corrupt differing neighboring objects. Enable sanity checks to find those. H. Diagnostics The current slab diagnostics are difficult to use and require a recompilation of the kernel. SLUB contains debugging code that is always available (but is kept out of the hot code paths). SLUB diagnostics can be enabled via the "slab_debug" option. Parameters can be specified to select a single or a group of slab caches for diagnostics. This means that the system is running with the usual performance and it is much more likely that race conditions can be reproduced. I. Resiliency If basic sanity checks are on then SLUB is capable of detecting common error conditions and recover as best as possible to allow the system to continue. J. Tracing Tracing can be enabled via the slab_debug=T,<slabcache> option during boot. SLUB will then protocol all actions on that slabcache and dump the object contents on free. K. On demand DMA cache creation. Generally DMA caches are not needed. If a kmalloc is used with __GFP_DMA then just create this single slabcache that is needed. For systems that have no ZONE_DMA requirement the support is completely eliminated. L. Performance increase Some benchmarks have shown speed improvements on kernbench in the range of 5-10%. The locking overhead of slub is based on the underlying base allocation size. If we can reliably allocate larger order pages then it is possible to increase slub performance much further. The anti-fragmentation patches may enable further performance increases. Tested on: i386 UP + SMP, x86_64 UP + SMP + NUMA emulation, IA64 NUMA + Simulator SLUB Boot options slub_nomerge Disable merging of slabs slub_min_order=x Require a minimum order for slab caches. This increases the managed chunk size and therefore reduces meta data and locking overhead. slub_min_objects=x Mininum objects per slab. Default is 8. slub_max_order=x Avoid generating slabs larger than order specified. slub_debug Enable all diagnostics for all caches slub_debug=<options> Enable selective options for all caches slub_debug=<o>,<cache> Enable selective options for a certain set of caches Available Debug options F Double Free checking, sanity and resiliency R Red zoning P Object / padding poisoning U Track last free / alloc T Trace all allocs / frees (only use for individual slabs). To use SLUB: Apply this patch and then select SLUB as the default slab allocator. [hugh@veritas.com: fix an oops-causing locking error] [akpm@linux-foundation.org: various stupid cleanups and small fixes] Signed-off-by:
Hugh Dickins <hugh@veritas.com> Signed-off-by:
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Andy Whitcroft authored
If device->num is zero we attempt to kmalloc() zero bytes. When SLUB is enabled this returns a null pointer and take that as an allocation failure and fail the device register. Check for no devices and avoid the allocation. [akpm: opportunistic kzalloc() conversion] Signed-off-by:
Andy Whitcroft <apw@shadowen.org> Signed-off-by:
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Christoph Lameter authored
i386 uses kmalloc to allocate the threadinfo structure assuming that the allocations result in a page sized aligned allocation. That has worked so far because SLAB exempts page sized slabs from debugging and aligns them in special ways that goes beyond the restrictions imposed by KMALLOC_ARCH_MINALIGN valid for other slabs in the kmalloc array. SLUB also works fine without debugging since page sized allocations neatly align at page boundaries. However, if debugging is switched on then SLUB will extend the slab with debug information. The resulting slab is not longer of page size. It will only be aligned following the requirements imposed by KMALLOC_ARCH_MINALIGN. As a result the threadinfo structure may not be page aligned which makes i386 fail to boot with SLUB debug on. Replace the calls to kmalloc with calls into the page allocator. An alternate solution may be to create a custom slab cache where the alignment is set to PAGE_SIZE. That would allow slub debugging to be applied to the threadinfo structure. Signed-off-by:
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David Rientjes authored
OOM killed tasks have access to memory reserves as specified by the TIF_MEMDIE flag in the hopes that it will quickly exit. If such a task has memory allocations constrained by cpusets, we may encounter a deadlock if a blocking task cannot exit because it cannot allocate the necessary memory. We allow tasks that have the TIF_MEMDIE flag to allocate memory anywhere, including outside its cpuset restriction, so that it can quickly die regardless of whether it is __GFP_HARDWALL. Cc: Andi Kleen <ak@suse.de> Cc: Paul Jackson <pj@sgi.com> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by:
David Rientjes <rientjes@google.com> Signed-off-by:
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Andrew Morton authored
It is only ever used prior to free_initmem(). (It will cause a warning when we run the section checking, but that's a false-positive and it simply changes the source of an existing warning, which is also a false-positive) Cc: Christoph Lameter <clameter@engr.sgi.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Signed-off-by:
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Mel Gorman authored
The sysctl handler for min_free_kbytes calls setup_per_zone_pages_min() on read or write. This function iterates through every zone and calls spin_lock_irqsave() on the zone LRU lock. When reading min_free_kbytes, this is a total waste of time that disables interrupts on the local processor. It might even be noticable machines with large numbers of zones if a process started constantly reading min_free_kbytes. This patch only calls setup_per_zone_pages_min() only on write. Tested on an x86 laptop and it did the right thing. Signed-off-by:
Mel Gorman <mel@csn.ul.ie> Acked-by:
Christoph Lameter <clameter@engr.sgi.com> Signed-off-by:
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Eric Dumazet authored
Some NUMA machines have a big MAX_NUMNODES (possibly 1024), but fewer possible nodes. This patch dynamically sizes the 'struct kmem_cache' to allocate only needed space. I moved nodelists[] field at the end of struct kmem_cache, and use the following computation in kmem_cache_init() cache_cache.buffer_size = offsetof(struct kmem_cache, nodelists) + nr_node_ids * sizeof(struct kmem_list3 *); On my two nodes x86_64 machine, kmem_cache.obj_size is now 192 instead of 704 (This is because on x86_64, MAX_NUMNODES is 64) On bigger NUMA setups, this might reduce the gfporder of "cache_cache" Signed-off-by:Eric Dumazet <dada1@cosmosbay.com> Cc: Pekka Enberg <penberg@cs.helsinki.fi> Cc: Andy Whitcroft <apw@shadowen.org> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by:
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Eric Dumazet authored
We can avoid allocating empty shared caches and avoid unecessary check of cache->limit. We save some memory. We avoid bringing into CPU cache unecessary cache lines. All accesses to l3->shared are already checking NULL pointers so this patch is safe. Signed-off-by:
Pekka Enberg <penberg@cs.helsinki.fi> Cc: Christoph Lameter <clameter@engr.sgi.com> Signed-off-by:
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Eric Dumazet authored
The existing comment in mm/slab.c is *perfect*, so I reproduce it : /* * CPU bound tasks (e.g. network routing) can exhibit cpu bound * allocation behaviour: Most allocs on one cpu, most free operations * on another cpu. For these cases, an efficient object passing between * cpus is necessary. This is provided by a shared array. The array * replaces Bonwick's magazine layer. * On uniprocessor, it's functionally equivalent (but less efficient) * to a larger limit. Thus disabled by default. */ As most shiped linux kernels are now compiled with CONFIG_SMP, there is no way a preprocessor #if can detect if the machine is UP or SMP. Better to use num_possible_cpus(). This means on UP we allocate a 'size=0 shared array', to be more efficient. Another patch can later avoid the allocations of 'empty shared arrays', to save some memory. Signed-off-by: -
Jan Kara authored
Rename file_ra_state.prev_page to prev_index and file_ra_state.offset to prev_offset. Also update of prev_index in do_generic_mapping_read() is now moved close to the update of prev_offset. [wfg@mail.ustc.edu.cn: fix it] Signed-off-by:
Jan Kara <jack@suse.cz> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Cc: WU Fengguang <wfg@mail.ustc.edu.cn> Signed-off-by:
Fengguang Wu <wfg@mail.ustc.edu.cn> Signed-off-by:
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Jan Kara authored
Introduce ra.offset and store in it an offset where the previous read ended. This way we can detect whether reads are really sequential (and thus we should not mark the page as accessed repeatedly) or whether they are random and just happen to be in the same page (and the page should really be marked accessed again). Signed-off-by:
Nick Piggin <nickpiggin@yahoo.com.au> Cc: WU Fengguang <wfg@mail.ustc.edu.cn> Signed-off-by:
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David Rientjes authored
Adds /proc/pid/clear_refs. When any non-zero number is written to this file, pte_mkold() and ClearPageReferenced() is called for each pte and its corresponding page, respectively, in that task's VMAs. This file is only writable by the user who owns the task. It is now possible to measure _approximately_ how much memory a task is using by clearing the reference bits with echo 1 > /proc/pid/clear_refs and checking the reference count for each VMA from the /proc/pid/smaps output at a measured time interval. For example, to observe the approximate change in memory footprint for a task, write a script that clears the references (echo 1 > /proc/pid/clear_refs), sleeps, and then greps for Pgs_Referenced and extracts the size in kB. Add the sizes for each VMA together for the total referenced footprint. Moments later, repeat the process and observe the difference. For example, using an efficient Mozilla: accumulated time referenced memory ---------------- ----------------- 0 s 408 kB 1 s 408 kB 2 s 556 kB 3 s 1028 kB 4 s 872 kB 5 s 1956 kB 6 s 416 kB 7 s 1560 kB 8 s 2336 kB 9 s 1044 kB 10 s 416 kB This is a valuable tool to get an approximate measurement of the memory footprint for a task. Cc: Hugh Dickins <hugh@veritas.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by:
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David Rientjes authored
Adds an additional unsigned long field to struct mem_size_stats called 'referenced'. For each pte walked in the smaps code, this field is incremented by PAGE_SIZE if it has pte-reference bits. An additional line was added to the /proc/pid/smaps output for each VMA to indicate how many pages within it are currently marked as referenced or accessed. Cc: Hugh Dickins <hugh@veritas.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by:
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David Rientjes authored
Extracts the pmd walker from smaps-specific code in fs/proc/task_mmu.c. The new struct pmd_walker includes the struct vm_area_struct of the memory to walk over. Iteration begins at the vma->vm_start and completes at vma->vm_end. A pointer to another data structure may be stored in the private field such as struct mem_size_stats, which acts as the smaps accumulator. For each pmd in the VMA, the action function is called with a pointer to its struct vm_area_struct, a pointer to the pmd_t, its start and end addresses, and the private field. The interface for walking pmd's in a VMA for fs/proc/task_mmu.c is now: void for_each_pmd(struct vm_area_struct *vma, void (*action)(struct vm_area_struct *vma, pmd_t *pmd, unsigned long addr, unsigned long end, void *private), void *private); Since the pmd walker is now extracted from the smaps code, smaps_one_pmd() is invoked for each pmd in the VMA. Its behavior and efficiency is identical to the existing implementation. Cc: Hugh Dickins <hugh@veritas.com> Cc: Paul Mundt <lethal@linux-sh.org> Cc: Christoph Lameter <clameter@sgi.com> Signed-off-by:
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Zachary Amsden authored
If you actually clear the bit, you need to: + pte_update_defer(vma->vm_mm, addr, ptep); The reason is, when updating PTEs, the hypervisor must be notified. Using atomic operations to do this is fine for all hypervisors I am aware of. However, for hypervisors which shadow page tables, if these PTE modifications are not trapped, you need a post-modification call to fulfill the update of the shadow page table. Acked-by:
Zachary Amsden <zach@vmware.com> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by:
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David Rientjes authored
Add ptep_test_and_clear_{dirty,young} to i386. They advertise that they have it and there is at least one place where it needs to be called without the page table lock: to clear the accessed bit on write to /proc/pid/clear_refs. ptep_clear_flush_{dirty,young} are updated to use the new functions. The overall net effect to current users of ptep_clear_flush_{dirty,young} is that we introduce an additional branch. Cc: Hugh Dickins <hugh@veritas.com> Cc: Ingo Molnar <mingo@redhat.com> Signed-off-by: -
Borislav Petkov authored
Introduce a macro for suppressing gcc from generating a warning about a probable uninitialized state of a variable. Example: - spinlock_t *ptl; + spinlock_t *uninitialized_var(ptl); Not a happy solution, but those warnings are obnoxious. - Using the usual pointlessly-set-it-to-zero approach wastes several bytes of text. - Using a macro means we can (hopefully) do something else if gcc changes cause the `x = x' hack to stop working - Using a macro means that people who are worried about hiding true bugs can easily turn it off. Signed-off-by:
Borislav Petkov <bbpetkov@yahoo.de> Signed-off-by:
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Nick Piggin authored
Identical block is duplicated twice: contrary to the comment, we have been re-reading the page *twice* in filemap_nopage rather than once. If any retry logic or anything is needed, it belongs in lower levels anyway. Only retry once. Linus agrees. Signed-off-by:
Nick Piggin <npiggin@suse.de> Signed-off-by:
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Andy Whitcroft authored
Generally we work under the assumption that memory the mem_map array is contigious and valid out to MAX_ORDER_NR_PAGES block of pages, ie. that if we have validated any page within this MAX_ORDER_NR_PAGES block we need not check any other. This is not true when CONFIG_HOLES_IN_ZONE is set and we must check each and every reference we make from a pfn. Add a pfn_valid_within() helper which should be used when scanning pages within a MAX_ORDER_NR_PAGES block when we have already checked the validility of the block normally with pfn_valid(). This can then be optimised away when we do not have holes within a MAX_ORDER_NR_PAGES block of pages. Signed-off-by:
Bob Picco <bob.picco@hp.com> Signed-off-by:
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Adrian Bunk authored
Add proper prototypes in include/linux/slab.h. Signed-off-by:
Adrian Bunk <bunk@stusta.de> Signed-off-by:
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Heiko Carstens authored
Architectures that don't support DMA can say so by adding a config NO_DMA to their Kconfig file. This will prevent compilation of some dma specific driver code. Also dma-mapping-broken.h isn't needed anymore on at least s390. This avoids compilation and linking of otherwise dead/broken code. Other architectures that include dma-mapping-broken.h are arm26, h8300, m68k, m68knommu and v850. If these could be converted as well we could get rid of the header file. Signed-off-by:
Heiko Carstens <heiko.carstens@de.ibm.com> "John W. Linville" <linville@tuxdriver.com> Cc: Kyle McMartin <kyle@parisc-linux.org> Cc: <James.Bottomley@SteelEye.com> Cc: Tejun Heo <htejun@gmail.com> Cc: Jeff Garzik <jeff@garzik.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: <geert@linux-m68k.org> Cc: <zippel@linux-m68k.org> Cc: <spyro@f2s.com> Cc: <uclinux-v850@lsi.nec.co.jp> Cc: <ysato@users.sourceforge.jp> Signed-off-by:
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Joshua N Pritikin authored
If the badness of a process is zero then oom_adj>0 has no effect. This patch makes sure that the oom_adj shift actually increases badness points appropriately. Signed-off-by:
Joshua N. Pritikin <jpritikin@pobox.com> Cc: Andrea Arcangeli <andrea@novell.com> Signed-off-by:
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Nick Piggin authored
__block_write_full_page is calling SetPageUptodate without the page locked. This is unusual, but not incorrect, as PG_writeback is still set. However the next patch will require that SetPageUptodate always be called with the page locked. Simply don't bother setting the page uptodate in this case (it is unusual that the write path does such a thing anyway). Instead just leave it to the read side to bring the page uptodate when it notices that all buffers are uptodate. Signed-off-by:
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Nick Piggin authored
Ensure pages are uptodate after returning from read_cache_page, which allows us to cut out most of the filesystem-internal PageUptodate calls. I didn't have a great look down the call chains, but this appears to fixes 7 possible use-before uptodate in hfs, 2 in hfsplus, 1 in jfs, a few in ecryptfs, 1 in jffs2, and a possible cleared data overwritten with readpage in block2mtd. All depending on whether the filler is async and/or can return with a !uptodate page. Signed-off-by:
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Pekka Enberg authored
If slab->inuse is corrupted, cache_alloc_refill can enter an infinite loop as detailed by Michael Richardson in the following post: <http://lkml.org/lkml/2007/2/16/292>. This adds a BUG_ON to catch those cases. Cc: Michael Richardson <mcr@sandelman.ca> Acked-by:
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Nick Piggin authored
Minimum gcc version is 3.2 now. However, with likely profiling, even modern gcc versions cannot always eliminate the call. Replace the placeholder functions with the more conventional empty static inlines, which should be optimal for everyone. Signed-off-by:
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Adrian Bunk authored
Add a proper prototype for hugetlb_get_unmapped_area() in include/linux/hugetlb.h. Signed-off-by:
William Irwin <wli@holomorphy.com> Signed-off-by:
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Christoph Lameter authored
We can use the global ZVC counters to establish the exact size of the LRU and the free pages. This allows a more accurate determination of the dirty ratio. This patch will fix the broken ratio calculations if large amounts of memory are allocated to huge pags or other consumers that do not put the pages on to the LRU. Notes: - I did not add NR_SLAB_RECLAIMABLE to the calculation of the dirtyable pages. Those may be reclaimable but they are at this point not dirtyable. If NR_SLAB_RECLAIMABLE would be considered then a huge number of reclaimable pages would stop writeback from occurring. - This patch used to be in mm as the last one in a series of patches. It was removed when Linus updated the treatment of highmem because there was a conflict. I updated the patch to follow Linus' approach. This patch is neede to fulfill the claims made in the beginning of the patchset that is now in Linus' tree. Signed-off-by:
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Christoph Lameter authored
The nr_cpu_ids value is currently only calculated in smp_init. However, it may be needed before (SLUB needs it on kmem_cache_init!) and other kernel components may also want to allocate dynamically sized per cpu array before smp_init. So move the determination of possible cpus into sched_init() where we already loop over all possible cpus early in boot. Also initialize both nr_node_ids and nr_cpu_ids with the highest value they could take. If we have accidental users before these values are determined then the current valud of 0 may cause too small per cpu and per node arrays to be allocated. If it is set to the maximum possible then we only waste some memory for early boot users. Signed-off-by:
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Jeremy Fitzhardinge authored
Add a new mm function apply_to_page_range() which applies a given function to every pte in a given virtual address range in a given mm structure. This is a generic alternative to cut-and-pasting the Linux idiomatic pagetable walking code in every place that a sequence of PTEs must be accessed. Although this interface is intended to be useful in a wide range of situations, it is currently used specifically by several Xen subsystems, for example: to ensure that pagetables have been allocated for a virtual address range, and to construct batched special pagetable update requests to map I/O memory (in ioremap()). [akpm@linux-foundation.org: fix warning, unpleasantly] Signed-off-by:
Ian Pratt <ian.pratt@xensource.com> Signed-off-by:
Christian Limpach <Christian.Limpach@cl.cam.ac.uk> Signed-off-by:
Chris Wright <chrisw@sous-sol.org> Signed-off-by:
Jeremy Fitzhardinge <jeremy@xensource.com> Cc: Christoph Lameter <clameter@sgi.com> Cc: Matt Mackall <mpm@waste.org> Acked-by:
Ingo Molnar <mingo@elte.hu> Signed-off-by:
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Jiri Slaby authored
serial_core, use pr_debug Signed-off-by:
Jiri Slaby <jirislaby@gmail.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by:
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Dave Jiang authored
The MPSC serial driver assumes that interrupt is always on to pick up the DMA transmit ops that aren't submitted while the DMA engine is active. However when irqs are off for a period of time such as operations under kernel crash dump console messages do not show up due to additional DMA ops are being dropped. This makes console writes to process through all the tx DMAs queued up before submitting a new request. Also, the current locking mechanism does not protect the hardware registers and ring buffer when a printk is done during the serial write operations. The additional per port transmit lock provides a finer granular locking and protects registers being clobbered while printks are nested within UART writes. Signed-off-by:
Dave Jiang <djiang@mvista.com> Signed-off-by:
Mark A. Greer <mgreer@mvista.com> Signed-off-by:
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David Gibson authored
At present, the serial core always allows setserial in userspace to change the port address, irq and base clock of any serial port. That makes sense for legacy ISA ports, but not for (say) embedded ns16550 compatible serial ports at peculiar addresses. In these cases, the kernel code configuring the ports must know exactly where they are, and their clocking arrangements (which can be unusual on embedded boards). It doesn't make sense for userspace to change these settings. Therefore, this patch defines a UPF_FIXED_PORT flag for the uart_port structure. If this flag is set when the serial port is configured, any attempts to alter the port's type, io address, irq or base clock with setserial are ignored. In addition this patch uses the new flag for on-chip serial ports probed in arch/powerpc/kernel/legacy_serial.c, and for other hard-wired serial ports probed by drivers/serial/of_serial.c. Signed-off-by:
David Gibson <dwg@au1.ibm.com> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by:
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Thomas Koeller authored
Add support for the integrated serial ports of the MIPS RM9122 processor and its relatives. The patch also does some whitespace cleanup. [akpm@linux-foundation.org: cleanups] Signed-off-by:
Thomas Koeller <thomas.koeller@baslerweb.com> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Russell King <rmk@arm.linux.org.uk> Signed-off-by:
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Marc St-Jean authored
Serial driver patch for the PMC-Sierra MSP71xx devices. There are three different fixes: 1 Fix for DesignWare APB THRE errata: In brief, this is a non-standard 16550 in that the THRE interrupt will not re-assert itself simply by disabling and re-enabling the THRI bit in the IER, it is only re-enabled if a character is actually sent out. It appears that the "8250-uart-backup-timer.patch" in the "mm" tree also fixes it so we have dropped our initial workaround. This patch now needs to be applied on top of that "mm" patch. 2 Fix for Busy Detect on LCR write: The DesignWare APB UART has a feature which causes a new Busy Detect interrupt to be generated if it's busy when the LCR is written. This fix saves the value of the LCR and rewrites it after clearing the interrupt. 3 Workaround for interrupt/data concurrency issue: The SoC needs to ensure that writes that can cause interrupts to be cleared reach the UART before returning from the ISR. This fix reads a non-destructive register on the UART so the read transaction completion ensures the previously queued write transaction has also completed. Signed-off-by:
Marc St-Jean <Marc_St-Jean@pmc-sierra.com> Cc: Russell King <rmk@arm.linux.org.uk> Cc: Ralf Baechle <ralf@linux-mips.org> Signed-off-by:
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Bernhard Walle authored
PCI drivers have the new_id file in sysfs which allows new IDs to be added at runtime. The advantage is to avoid re-compilation of a driver that works for a new device, but it's ID table doesn't contain the new device. This mechanism is only meant for testing, after the driver has been tested successfully, the ID should be added in source code so that new revisions of the kernel automatically detect the device. The implementation follows the PCI implementation. The interface is documented in Documentation/pcmcia/driver.txt. Computations should be done in userspace, so the sysfs string contains the raw structure members for matching. Signed-off-by:
Bernhard Walle <bwalle@suse.de> Cc: Dominik Brodowski <linux@dominikbrodowski.net> Cc: Greg KH <greg@kroah.com> Signed-off-by:
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