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2006-01-08[PATCH] cpuset: memory pressure meterPaul Jackson
Provide a simple per-cpuset metric of memory pressure, tracking the -rate- that the tasks in a cpuset call try_to_free_pages(), the synchronous (direct) memory reclaim code. This enables batch managers monitoring jobs running in dedicated cpusets to efficiently detect what level of memory pressure that job is causing. This is useful both on tightly managed systems running a wide mix of submitted jobs, which may choose to terminate or reprioritize jobs that are trying to use more memory than allowed on the nodes assigned them, and with tightly coupled, long running, massively parallel scientific computing jobs that will dramatically fail to meet required performance goals if they start to use more memory than allowed to them. This patch just provides a very economical way for the batch manager to monitor a cpuset for signs of memory pressure. It's up to the batch manager or other user code to decide what to do about it and take action. ==> Unless this feature is enabled by writing "1" to the special file /dev/cpuset/memory_pressure_enabled, the hook in the rebalance code of __alloc_pages() for this metric reduces to simply noticing that the cpuset_memory_pressure_enabled flag is zero. So only systems that enable this feature will compute the metric. Why a per-cpuset, running average: Because this meter is per-cpuset, rather than per-task or mm, the system load imposed by a batch scheduler monitoring this metric is sharply reduced on large systems, because a scan of the tasklist can be avoided on each set of queries. Because this meter is a running average, instead of an accumulating counter, a batch scheduler can detect memory pressure with a single read, instead of having to read and accumulate results for a period of time. Because this meter is per-cpuset rather than per-task or mm, the batch scheduler can obtain the key information, memory pressure in a cpuset, with a single read, rather than having to query and accumulate results over all the (dynamically changing) set of tasks in the cpuset. A per-cpuset simple digital filter (requires a spinlock and 3 words of data per-cpuset) is kept, and updated by any task attached to that cpuset, if it enters the synchronous (direct) page reclaim code. A per-cpuset file provides an integer number representing the recent (half-life of 10 seconds) rate of direct page reclaims caused by the tasks in the cpuset, in units of reclaims attempted per second, times 1000. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] mm: free_pages optNick Piggin
Try to streamline free_pages_bulk by ensuring callers don't pass in a 'count' that exceeds the list size. Some cleanups: Rename __free_pages_bulk to __free_one_page. Put the page list manipulation from __free_pages_ok into free_one_page. Make __free_pages_ok static. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] mm: cleanup zone_pcpNick Piggin
Use zone_pcp everywhere even though NUMA code "knows" the internal details of the zone. Stop other people trying to copy, and it looks nicer. Also, only print the pagesets of online cpus in zoneinfo. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: "Seth, Rohit" <rohit.seth@intel.com> Cc: Christoph Lameter <christoph@lameter.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] Make high and batch sizes of per_cpu_pagelists configurableRohit Seth
As recently there has been lot of traffic on the right values for batch and high water marks for per_cpu_pagelists. This patch makes these two variables configurable through /proc interface. A new tunable /proc/sys/vm/percpu_pagelist_fraction is added. This entry controls the fraction of pages at most in each zone that are allocated for each per cpu page list. The min value for this is 8. It means that we don't allow more than 1/8th of pages in each zone to be allocated in any single per_cpu_pagelist. The batch value of each per cpu pagelist is also updated as a result. It is set to pcp->high/4. The upper limit of batch is (PAGE_SHIFT * 8) Signed-off-by: Rohit Seth <rohit.seth@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] slab: remove nested #ifdef CONFIG_NUMAChristoph Lameter
For some reason there is an #ifdef CONFIG_NUMA within another #ifdef CONFIG_NUMA in the page allocator. Remove innermost #ifdef CONFIG_NUMA Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-08[PATCH] revert "mm: page_state fixes"Andrew Morton
Hugh says: page_alloc_cpu_notify() specifically contains code to /* Add dead cpu's page_states to our own. */ which handles this more efficiently. Cc: Hugh Dickins <hugh@veritas.com> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: page_state optNick Piggin
Optimise page_state manipulations by introducing interrupt unsafe accessors to page_state fields. Callers must provide their own locking (either disable interrupts or not update from interrupt context). Switch over the hot callsites that can easily be moved under interrupts off sections. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] build_zonelists_node(): rename argsChristoph Lameter
Give j and r meaningful names. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] Fix zone policy determinationChristoph Lameter
The use k in the inner loop means that the highest zone nr is always used if any zone of a node is populated. This means that the policy zone is not correctly determined on arches that do no use HIGHMEM like ia64. Change the loop to decrement k which also simplifies the BUG_ON. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: move determination of policy_zone into page allocatorChristoph Lameter
Currently the function to build a zonelist for a BIND policy has the side effect to set the policy_zone. This seems to be a bit strange. policy zone seems to not be initialized elsewhere and therefore 0. Do we police ZONE_DMA if no bind policy has been used yet? This patch moves the determination of the zone to apply policies to into the page allocator. We determine the zone while building the zonelist for nodes. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: simplify build_zonelists_node by removing the case statement.Christoph Lameter
Simplify build_zonelists_node by removing the case statement. Signed-off-by: Christoph Lameter <clameter@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: add populated_zone() helperCon Kolivas
There are numerous places we check whether a zone is populated or not. Provide a helper function to check for populated zones and convert all checks for zone->present_pages. Signed-off-by: Con Kolivas <kernel@kolivas.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: bad_page optimisationNick Piggin
Cut down size slightly by not passing bad_page the function name (it should be able to be determined by dump_stack()). And cut down the number of printks in bad_page. Also, cut down some branching in the destroy_compound_page path. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: dma32 zone statisticsNick Piggin
Add dma32 to zone statistics. Also attempt to arrange struct page_state a bit better (visually). Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Andi Kleen <ak@muc.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] FRV: Clean up bootmem allocator's page freeing algorithmDavid Howells
The attached patch cleans up the way the bootmem allocator frees pages. A new function, __free_pages_bootmem(), is provided in mm/page_alloc.c that is called from mm/bootmem.c to turn pages over to the main allocator. All the bits of code to initialise pages (clearing PG_reserved and setting the page count) are moved to here. The checks on page validity are removed, on the assumption that the struct page arrays will have been prepared correctly. Signed-off-by: David Howells <dhowells@redhat.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: page_alloc cleanupsNick Piggin
Small cleanups that does not change generated code with the gcc's I've tested with. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: page_state fixesNick Piggin
read_page_state and __get_page_state only traverse online CPUs, which will cause results to fluctuate when CPUs are plugged in or out. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: remove pcp lowNick Piggin
struct per_cpu_pages.low is useless. Remove it. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: remove bad_rangeNick Piggin
bad_range is supposed to be a temporary check. It would be a pity to throw it out. Make it depend on CONFIG_DEBUG_VM instead. CONFIG_HOLES_IN_ZONE systems were relying on this to check pfn_valid in the page allocator. Add that to page_is_buddy instead. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: microopt conditionsNick Piggin
Micro optimise some conditionals where we don't need lazy evaluation. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: set_page_refs optNick Piggin
Inline set_page_refs. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: pagealloc optNick Piggin
Slightly optimise some page allocation and freeing functions by taking advantage of knowing whether or not interrupts are disabled. Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: remove arch independent NODES_SPAN_OTHER_NODESMike Kravetz
The NODES_SPAN_OTHER_NODES config option was created so that DISCONTIGMEM could handle pSeries numa layouts. However, support for DISCONTIGMEM has been replaced by SPARSEMEM on powerpc. As a result, this config option and supporting code is no longer needed. I have already sent a patch to Paul that removes the option from powerpc specific code. This removes the arch independent piece. Doesn't really matter which is applied first. Signed-off-by: Mike Kravetz <kravetz@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2006-01-06[PATCH] mm: fix __alloc_pages cpuset ALLOC_* flagsPaul Jackson
Two changes to the setting of the ALLOC_CPUSET flag in mm/page_alloc.c:__alloc_pages() - A bug fix - the "ignoring mins" case should not be honoring ALLOC_CPUSET. This case of all cases, since it is handling a request that will free up more memory than is asked for (exiting tasks, e.g.) should be allowed to escape cpuset constraints when memory is tight. - A logic change to make it simpler. Honor cpusets even on GFP_ATOMIC (!wait) requests. With this, cpuset confinement applies to all requests except ALLOC_NO_WATERMARKS, so that in a subsequent cleanup patch, I can remove the ALLOC_CPUSET flag entirely. Since I don't know any real reason this logic has to be either way, I am choosing the path of the simplest code. Signed-off-by: Paul Jackson <pj@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-12-15[PATCH] missing prototype (mm/page_alloc.c)Al Viro
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-12-03[PATCH] Fix up per-cpu page batch sizesNick Piggin
The code to clamp batch sizes to 2^n - 1 went missing and an extra check got added, which must have been a hunk of the "higer order pcp batch refills" work sneaking in. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-28[PATCH] mm: __alloc_pages cleanup fixNick Piggin
I believe this patch is required to fix breakage in the asynch reclaim watermark logic introduced by this patch: http://www.kernel.org/git/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiff;h=7fb1d9fca5c6e3b06773b69165a73f3fb786b8ee Just some background of the watermark logic in case it isn't clear... Basically what we have is this: --- pages_high | | (a) | --- pages_low | | (b) | --- pages_min | | (c) | --- 0 Now when pages_low is reached, we want to kick asynch reclaim, which gives us an interval of "b" before we must start synch reclaim, and gives kswapd an interval of "a" before it need go back to sleep. When pages_min is reached, normal allocators must enter synch reclaim, but PF_MEMALLOC, ALLOC_HARDER, and ALLOC_HIGH (ie. atomic allocations, recursive allocations, etc.) get access to varying amounts of the reserve "c". Signed-off-by: Nick Piggin <npiggin@suse.de> Cc: "Seth, Rohit" <rohit.seth@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-22[PATCH] unpaged: PG_reserved bad_pageHugh Dickins
It used to be the case that PG_reserved pages were silently never freed, but in 2.6.15-rc1 they may be freed with a "Bad page state" message. We should work through such cases as they appear, fixing the code; but for now it's safer to issue the message without freeing the page, leaving PG_reserved set. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-22[PATCH] unpaged: unifdefed PageCompoundHugh Dickins
It looks like snd_xxx is not the only nopage to be using PageReserved as a way of holding a high-order page together: which no longer works, but is masked by our failure to free from VM_RESERVED areas. We cannot fix that bug without first substituting another way to hold the high-order page together, while farming out the 0-order pages from within it. That's just what PageCompound is designed for, but it's been kept under CONFIG_HUGETLB_PAGE. Remove the #ifdefs: which saves some space (out- of-line put_page), doesn't slow down what most needs to be fast (already using hugetlb), and unifies the way we handle high-order pages. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-17[PATCH] VM: fix zone list restart in page allocatateJens Axboe
We must reassign z before looping through the zones kicking kswapd, since it will be NULL if we hit an OOM condition and jump back to the beginning again. 'z' is initially assigned before the restart: label. So move the restart label up a little. Signed-off-by: Jens Axboe <axboe@suse.de>
2005-11-14Merge x86-64 update from AndiLinus Torvalds
2005-11-14[PATCH] x86_64: Remove obsolete ARCH_HAS_ATOMIC_UNSIGNED and page_flags_tAndi Kleen
Has been introduced for x86-64 at some point to save memory in struct page, but has been obsolete for some time. Just remove it. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-14[PATCH] x86_64: When cpu_up fails clean up page allocator properlyAndi Kleen
Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-14[PATCH] x86_64: Add 4GB DMA32 zoneAndi Kleen
Add a new 4GB GFP_DMA32 zone between the GFP_DMA and GFP_NORMAL zones. As a bit of historical background: when the x86-64 port was originally designed we had some discussion if we should use a 16MB DMA zone like i386 or a 4GB DMA zone like IA64 or both. Both was ruled out at this point because it was in early 2.4 when VM is still quite shakey and had bad troubles even dealing with one DMA zone. We settled on the 16MB DMA zone mainly because we worried about older soundcards and the floppy. But this has always caused problems since then because device drivers had trouble getting enough DMA able memory. These days the VM works much better and the wide use of NUMA has proven it can deal with many zones successfully. So this patch adds both zones. This helps drivers who need a lot of memory below 4GB because their hardware is not accessing more (graphic drivers - proprietary and free ones, video frame buffer drivers, sound drivers etc.). Previously they could only use IOMMU+16MB GFP_DMA, which was not enough memory. Another common problem is that hardware who has full memory addressing for >4GB misses it for some control structures in memory (like transmit rings or other metadata). They tended to allocate memory in the 16MB GFP_DMA or the IOMMU/swiotlb then using pci_alloc_consistent, but that can tie up a lot of precious 16MB GFPDMA/IOMMU/swiotlb memory (even on AMD systems the IOMMU tends to be quite small) especially if you have many devices. With the new zone pci_alloc_consistent can just put this stuff into memory below 4GB which works better. One argument was still if the zone should be 4GB or 2GB. The main motivation for 2GB would be an unnamed not so unpopular hardware raid controller (mostly found in older machines from a particular four letter company) who has a strange 2GB restriction in firmware. But that one works ok with swiotlb/IOMMU anyways, so it doesn't really need GFP_DMA32. I chose 4GB to be compatible with IA64 and because it seems to be the most common restriction. The new zone is so far added only for x86-64. For other architectures who don't set up this new zone nothing changes. Architectures can set a compatibility define in Kconfig CONFIG_DMA_IS_DMA32 that will define GFP_DMA32 as GFP_DMA. Otherwise it's a nop because on 32bit architectures it's normally not needed because GFP_NORMAL (=0) is DMA able enough. One problem is still that GFP_DMA means different things on different architectures. e.g. some drivers used to have #ifdef ia64 use GFP_DMA (trusting it to be 4GB) #elif __x86_64__ (use other hacks like the swiotlb because 16MB is not enough) ... . This was quite ugly and is now obsolete. These should be now converted to use GFP_DMA32 unconditionally. I haven't done this yet. Or best only use pci_alloc_consistent/dma_alloc_coherent which will use GFP_DMA32 transparently. Signed-off-by: Andi Kleen <ak@suse.de> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-13[PATCH] mm: highmem watermarksNick Piggin
The pages_high - pages_low and pages_low - pages_min deltas are the asynch reclaim watermarks. As such, the should be in the same ratios as any other zone for highmem zones. It is the pages_min - 0 delta which is the PF_MEMALLOC reserve, and this is the region that isn't very useful for highmem. This patch ensures highmem systems have similar characteristics as non highmem ones with the same amount of memory, and also that highmem zones get similar reclaim pressures to other zones. Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-13[PATCH] mm: __alloc_pages cleanupRohit Seth
Clean up of __alloc_pages. Restoration of previous behaviour, plus further cleanups by introducing an 'alloc_flags', removing the last of should_reclaim_zone. Signed-off-by: Rohit Seth <rohit.seth@intel.com> Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-13[PATCH] mm: __GFP_NOFAIL fixKirill Korotaev
In __alloc_pages(): if ((p->flags & (PF_MEMALLOC | PF_MEMDIE)) && !in_interrupt()) { /* go through the zonelist yet again, ignoring mins */ for (i = 0; zones[i] != NULL; i++) { struct zone *z = zones[i]; page = buffered_rmqueue(z, order, gfp_mask); if (page) { zone_statistics(zonelist, z); goto got_pg; } } goto nopage; <<<< HERE!!! FAIL... } kswapd (which has PF_MEMALLOC flag) can fail to allocate memory even when it allocates it with __GFP_NOFAIL flag. Signed-Off-By: Pavel Emelianov <xemul@sw.ru> Signed-Off-By: Denis Lunev <den@sw.ru> Signed-Off-By: Kirill Korotaev <dev@sw.ru> Cc: Nick Piggin <nickpiggin@yahoo.com.au> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-10[PATCH] Don't print per-cpu vm stats for offline cpus.Dave Jones
I just hit a page allocation error on a kernel configured to support 64 CPUs. It spewed 60 completely useless unnecessary lines of info. Signed-off-by: Dave Jones <davej@redhat.com> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-11-07[PATCH] unexport nr_swap_pagesAdrian Bunk
I didn't find any possible modular usage in the kernel. Signed-off-by: Adrian Bunk <bunk@stusta.de> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] mm: wider use of for_each_*cpu()John Hawkes
In 'mm' change the explicit use of a for-loop using NR_CPUS into the general for_each_cpu() constructs. This widens the scope of potential future optimizations of the general constructs, as well as takes advantage of the existing optimizations of first_cpu() and next_cpu(), which is advantageous when the true CPU count is much smaller than NR_CPUS. Signed-off-by: John Hawkes <hawkes@sgi.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] memory hotplug: sysfs and add/remove functionsDave Hansen
This adds generic memory add/remove and supporting functions for memory hotplug into a new file as well as a memory hotplug kernel config option. Individual architecture patches will follow. For now, disable memory hotplug when swsusp is enabled. There's a lot of churn there right now. We'll fix it up properly once it calms down. Signed-off-by: Matt Tolentino <matthew.e.tolentino@intel.com> Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] memory hotplug locking: zone span seqlockDave Hansen
See the "fixup bad_range()" patch for more information, but this actually creates a the lock to protect things making assumptions about a zone's size staying constant at runtime. Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] memory hotplug locking: node_size_lockDave Hansen
pgdat->node_size_lock is basically only neeeded in one place in the normal code: show_mem(), which is the arch-specific sysrq-m printing function. Strictly speaking, the architectures not doing memory hotplug do no need this locking in show_mem(). However, they are all included for completeness. This should also make any future consolidation of all of the implementations a little more straightforward. This lock is also held in the sparsemem code during a memory removal, as sections are invalidated. This is the place there pfn_valid() is made false for a memory area that's being removed. The lock is only required when doing pfn_valid() operations on memory which the user does not already have a reference on the page, such as in show_mem(). Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] memory hotplug prep: fixup bad_range()Dave Hansen
When doing memory hotplug operations, the size of existing zones can obviously change. This means that zone->zone_{start_pfn,spanned_pages} can change. There are currently no locks that protect these structure members. However, they are rarely accessed at runtime. Outside of swsusp, the only place that I can find is bad_range(). So, split bad_range() up into two pieces: one that needs to be locked and anther that doesn't. Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] memory hotplug prep: break out zone initializationDave Hansen
If a zone is empty at boot-time and then hot-added to later, it needs to run the same init code that would have been run on it at boot. This patch breaks out zone table and per-cpu-pages functions for use by the hotplug code. You can almost see all of the free_area_init_core() function on one page now. :) Signed-off-by: Dave Hansen <haveblue@us.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] mm: split page table lockHugh Dickins
Christoph Lameter demonstrated very poor scalability on the SGI 512-way, with a many-threaded application which concurrently initializes different parts of a large anonymous area. This patch corrects that, by using a separate spinlock per page table page, to guard the page table entries in that page, instead of using the mm's single page_table_lock. (But even then, page_table_lock is still used to guard page table allocation, and anon_vma allocation.) In this implementation, the spinlock is tucked inside the struct page of the page table page: with a BUILD_BUG_ON in case it overflows - which it would in the case of 32-bit PA-RISC with spinlock debugging enabled. Splitting the lock is not quite for free: another cacheline access. Ideally, I suppose we would use split ptlock only for multi-threaded processes on multi-cpu machines; but deciding that dynamically would have its own costs. So for now enable it by config, at some number of cpus - since the Kconfig language doesn't support inequalities, let preprocessor compare that with NR_CPUS. But I don't think it's worth being user-configurable: for good testing of both split and unsplit configs, split now at 4 cpus, and perhaps change that to 8 later. There is a benefit even for singly threaded processes: kswapd can be attacking one part of the mm while another part is busy faulting. Signed-off-by: Hugh Dickins <hugh@veritas.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] core remove PageReservedNick Piggin
Remove PageReserved() calls from core code by tightening VM_RESERVED handling in mm/ to cover PageReserved functionality. PageReserved special casing is removed from get_page and put_page. All setting and clearing of PageReserved is retained, and it is now flagged in the page_alloc checks to help ensure we don't introduce any refcount based freeing of Reserved pages. MAP_PRIVATE, PROT_WRITE of VM_RESERVED regions is tentatively being deprecated. We never completely handled it correctly anyway, and is be reintroduced in future if required (Hugh has a proof of concept). Once PageReserved() calls are removed from kernel/power/swsusp.c, and all arch/ and driver code, the Set and Clear calls, and the PG_reserved bit can be trivially removed. Last real user of PageReserved is swsusp, which uses PageReserved to determine whether a struct page points to valid memory or not. This still needs to be addressed (a generic page_is_ram() should work). A last caveat: the ZERO_PAGE is now refcounted and managed with rmap (and thus mapcounted and count towards shared rss). These writes to the struct page could cause excessive cacheline bouncing on big systems. There are a number of ways this could be addressed if it is an issue. Signed-off-by: Nick Piggin <npiggin@suse.de> Refcount bug fix for filemap_xip.c Signed-off-by: Carsten Otte <cotte@de.ibm.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] mm: set per-cpu-pages lower threshold to zeroSeth, Rohit
Set the low water mark for hot pages in pcp to zero. (akpm: for the life of me I cannot remember why we created pcp->low. Neither can Martin and the changelog is silent. Maybe it was just a brainfart, but I have this feeling that there was a reason. If not, we should remove the fields completely. We'll see.) Signed-off-by: Rohit Seth <rohit.seth@intel.com> Cc: <linux-mm@kvack.org> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-29[PATCH] mm: page_alloc: increase size of per-cpu-pagesSeth, Rohit
Increase the page allocator's per-cpu magazines from 1/4MB to 1/2MB. Over 100+ runs for a workload, the difference in mean is about 2%. The best results for both are almost same. Though the max variation in results with 1/2MB is only 2.2%, whereas with 1/4MB it is 12%. Signed-off-by: Rohit Seth <rohit.seth@intel.com> Signed-off-by: Andrew Morton <akpm@osdl.org> Signed-off-by: Linus Torvalds <torvalds@osdl.org>
2005-10-28[PATCH] gfp_t: the restAl Viro
zone handling, mapping->flags handling Signed-off-by: Al Viro <viro@zeniv.linux.org.uk> Signed-off-by: Linus Torvalds <torvalds@osdl.org>