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>
Conversion of nr_writeback to per zone counter.
This removes the last page_state counter from arch/i386/mm/pgtable.c so we
drop the page_state from there.
[akpm@osdl.org: bugfix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
This makes nr_dirty a per zone counter. Looping over all processors is
avoided during writeback state determination.
The counter aggregation for nr_dirty had to be undone in the NFS layer since
we summed up the page counts from multiple zones. Someone more familiar with
NFS should probably review what I have done.
[akpm@osdl.org: bugfix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Conversion of nr_page_table_pages to a per zone counter
[akpm@osdl.org: bugfix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
- Allows reclaim to access counter without looping over processor counts.
- Allows accurate statistics on how many pages are used in a zone by
the slab. This may become useful to balance slab allocations over
various zones.
[akpm@osdl.org: bugfix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Currently a single atomic variable is used to establish the size of the page
cache in the whole machine. The zoned VM counters have the same method of
implementation as the nr_pagecache code but also allow the determination of
the pagecache size per zone.
Remove the special implementation for nr_pagecache and make it a zoned counter
named NR_FILE_PAGES.
Updates of the page cache counters are always performed with interrupts off.
We can therefore use the __ variant here.
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
nr_mapped is important because it allows a determination of how many pages of
a zone are not mapped, which would allow a more efficient means of determining
when we need to reclaim memory in a zone.
We take the nr_mapped field out of the page state structure and define a new
per zone counter named NR_FILE_MAPPED (the anonymous pages will be split off
from NR_MAPPED in the next patch).
We replace the use of nr_mapped in various kernel locations. This avoids the
looping over all processors in try_to_free_pages(), writeback, reclaim (swap +
zone reclaim).
[akpm@osdl.org: bugfix]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Per zone counter infrastructure
The counters that we currently have for the VM are split per processor. The
processor however has not much to do with the zone these pages belong to. We
cannot tell f.e. how many ZONE_DMA pages are dirty.
So we are blind to potentially inbalances in the usage of memory in various
zones. F.e. in a NUMA system we cannot tell how many pages are dirty on a
particular node. If we knew then we could put measures into the VM to balance
the use of memory between different zones and different nodes in a NUMA
system. For example it would be possible to limit the dirty pages per node so
that fast local memory is kept available even if a process is dirtying huge
amounts of pages.
Another example is zone reclaim. We do not know how many unmapped pages exist
per zone. So we just have to try to reclaim. If it is not working then we
pause and try again later. It would be better if we knew when it makes sense
to reclaim unmapped pages from a zone. This patchset allows the determination
of the number of unmapped pages per zone. We can remove the zone reclaim
interval with the counters introduced here.
Futhermore the ability to have various usage statistics available will allow
the development of new NUMA balancing algorithms that may be able to improve
the decision making in the scheduler of when to move a process to another node
and hopefully will also enable automatic page migration through a user space
program that can analyse the memory load distribution and then rebalance
memory use in order to increase performance.
The counter framework here implements differential counters for each processor
in struct zone. The differential counters are consolidated when a threshold
is exceeded (like done in the current implementation for nr_pageache), when
slab reaping occurs or when a consolidation function is called.
Consolidation uses atomic operations and accumulates counters per zone in the
zone structure and also globally in the vm_stat array. VM functions can
access the counts by simply indexing a global or zone specific array.
The arrangement of counters in an array also simplifies processing when output
has to be generated for /proc/*.
Counters can be updated by calling inc/dec_zone_page_state or
_inc/dec_zone_page_state analogous to *_page_state. The second group of
functions can be called if it is known that interrupts are disabled.
Special optimized increment and decrement functions are provided. These can
avoid certain checks and use increment or decrement instructions that an
architecture may provide.
We also add a new CONFIG_DMA_IS_NORMAL that signifies that an architecture can
do DMA to all memory and therefore ZONE_NORMAL will not be populated. This is
only currently set for IA64 SGI SN2 and currently only affects
node_page_state(). In the best case node_page_state can be reduced to
retrieving a single counter for the one zone on the node.
[akpm@osdl.org: cleanups]
[akpm@osdl.org: export vm_stat[] for filesystems]
Signed-off-by: Christoph Lameter <clameter@sgi.com>
Cc: Trond Myklebust <trond.myklebust@fys.uio.no>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
register_cpu_notifier() cannot do anything in a module, in a
!CONFIG_HOTPLUG_CPU kernel.
Cc: Chandra Seetharaman <sekharan@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
* master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6: (30 commits)
[TIPC]: Initial activation message now includes TIPC version number
[TIPC]: Improve response to requests for node/link information
[TIPC]: Fixed skb_under_panic caused by tipc_link_bundle_buf
[IrDA]: Fix the AU1000 FIR dependencies
[IrDA]: Fix RCU lock pairing on error path
[XFRM]: unexport xfrm_state_mtu
[NET]: make skb_release_data() static
[NETFILTE] ipv4: Fix typo (Bugzilla #6753)
[IrDA]: MCS7780 usb_driver struct should be static
[BNX2]: Turn off link during shutdown
[BNX2]: Use dev_kfree_skb() instead of the _irq version
[ATM]: basic sysfs support for ATM devices
[ATM]: [suni] change suni_init to __devinit
[ATM]: [iphase] should be __devinit not __init
[ATM]: [idt77105] should be __devinit not __init
[BNX2]: Add NETIF_F_TSO_ECN
[NET]: Add ECN support for TSO
[AF_UNIX]: Datagram getpeersec
[NET]: Fix logical error in skb_gso_ok
[PKT_SCHED]: PSCHED_TADD() and PSCHED_TADD2() can result,tv_usec >= 1000000
...
skb_release_data() no longer has any users in other files.
Signed-off-by: Adrian Bunk <bunk@stusta.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
Happily, life is much simpler on 32-bit sparc systems.
The "intr" property, preferred over the "interrupts"
property is used-as. Some minor translations of this
value happen on sun4d systems.
The stage is now set to rewrite the sparc serial driver
probing to use the of_driver framework, and then to convert
all SBUS, EBUS, and ISA drivers in-kind so that we can nuke
all those special bus frameworks.
Signed-off-by: David S. Miller <davem@davemloft.net>
Do IRQ determination generically by parsing the PROM properties,
and using IRQ controller drivers for final resolution.
One immediate positive effect is that all of the IRQ frobbing
in the EBUS, ISA, and PCI controller layers has been eliminated.
We just look up the of_device and use the properly computed
value.
The PCI controller irq_build() routines are gone and no longer
used. Unfortunately sbus_build_irq() has to remain as there is
a direct reference to this in the sunzilog driver. That can be
killed off once the sparc32 side of this is written and the
sunzilog driver is transformed into an "of" bus driver.
Signed-off-by: David S. Miller <davem@davemloft.net>
This needs to be a unique interrupt source because we do
not have a register or similar to poll to make sure the
IRQ is really for us. We do not have any dev_id to pass
in anyways, and the generic IRQ layer is now enforcing
that when SA_SHIRQ is specified, dev_id must be non-NULL.
Signed-off-by: David S. Miller <davem@davemloft.net>
On sparc64 we don't need to do this because the resource
values are large enough to encode the full physical address.
Signed-off-by: David S. Miller <davem@davemloft.net>
The idea is to fully construct the device register and
interrupt values into these of_device objects, and convert
all of SBUS, EBUS, ISA drivers to use this new stuff.
Much ideas and code taken from Ben H.'s powerpc work.
Signed-off-by: David S. Miller <davem@davemloft.net>
Totally unused.
We need to traverse the list of global IRQ translaters,
so storing it in the per-bus structures was useless.
Signed-off-by: David S. Miller <davem@davemloft.net>
* git://git.kernel.org/pub/scm/linux/kernel/git/gregkh/devfs-2.6: (22 commits)
[PATCH] devfs: Remove it from the feature_removal.txt file
[PATCH] devfs: Last little devfs cleanups throughout the kernel tree.
[PATCH] devfs: Rename TTY_DRIVER_NO_DEVFS to TTY_DRIVER_DYNAMIC_DEV
[PATCH] devfs: Remove the tty_driver devfs_name field as it's no longer needed
[PATCH] devfs: Remove the line_driver devfs_name field as it's no longer needed
[PATCH] devfs: Remove the videodevice devfs_name field as it's no longer needed
[PATCH] devfs: Remove the gendisk devfs_name field as it's no longer needed
[PATCH] devfs: Remove the miscdevice devfs_name field as it's no longer needed
[PATCH] devfs: Remove the devfs_fs_kernel.h file from the tree
[PATCH] devfs: Remove devfs_remove() function from the kernel tree
[PATCH] devfs: Remove devfs_mk_cdev() function from the kernel tree
[PATCH] devfs: Remove devfs_mk_bdev() function from the kernel tree
[PATCH] devfs: Remove devfs_mk_symlink() function from the kernel tree
[PATCH] devfs: Remove devfs_mk_dir() function from the kernel tree
[PATCH] devfs: Remove devfs_*_tape() functions from the kernel tree
[PATCH] devfs: Remove devfs support from the sound subsystem
[PATCH] devfs: Remove devfs support from the ide subsystem.
[PATCH] devfs: Remove devfs support from the serial subsystem
[PATCH] devfs: Remove devfs from the init code
[PATCH] devfs: Remove devfs from the partition code
...
* 'upstream' of git://ftp.linux-mips.org/pub/scm/upstream-linus: (33 commits)
[MIPS] Add missing backslashes to macro definitions.
[MIPS] Death list of board support to be removed after 2.6.18.
[MIPS] Remove BSD and Sys V compat data types.
[MIPS] ioc3.h: Uses u8, so include <linux/types.h>.
[MIPS] 74K: Assume it will also have an AR bit in config7
[MIPS] Treat CPUs with AR bit as physically indexed.
[MIPS] Oprofile: Support VSMP on 34K.
[MIPS] MIPS32/MIPS64 S-cache fix and cleanup
[MIPS] excite: PCI makefile needs to use += if it wants a chance to work.
[MIPS] excite: plat_setup -> plat_mem_setup.
[MIPS] au1xxx: export dbdma functions
[MIPS] au1xxx: dbdma, no sleeping under spin_lock
[MIPS] au1xxx: fix PSC_SMBTXRX_RSR.
[MIPS] Early printk for IP27.
[MIPS] Fix handling of 0 length I & D caches.
[MIPS] Typo fixes.
[MIPS] MIPS32/MIPS64 secondary cache management
[MIPS] Fix FIXADDR_TOP for TX39/TX49.
[MIPS] Remove first timer interrupt setup in wrppmc_timer_setup()
[MIPS] Fix configuration of R2 CPU features and multithreading.
...
This patch removes unused system type name.
DDB5074 and DDB5476 were already removed.
Signed-off-by: Yoichi Yuasa <yoichi_yuasa@tripeaks.co.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>
