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Reimplement augmented RB-trees without sprinkling extra branches
all over the RB-tree code (which lives in the scheduler hot path).
This approach is 'borrowed' from Fabio's BFQ implementation and
relies on traversing the rebalance path after the RB-tree-op to
correct the heap property for insertion/removal and make up for
the damage done by the tree rotations.
For insertion the rebalance path is trivially that from the new
node upwards to the root, for removal it is that from the deepest
node in the path from the to be removed node that will still
be around after the removal.
[ This patch also fixes a video driver regression reported by
Ali Gholami Rudi - the memtype->subtree_max_end was updated
incorrectly. ]
Acked-by: Suresh Siddha <suresh.b.siddha@intel.com>
Acked-by: Venkatesh Pallipadi <venki@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Tested-by: Ali Gholami Rudi <ali@rudi.ir>
Cc: Fabio Checconi <fabio@gandalf.sssup.it>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
LKML-Reference: <1275414172.27810.27961.camel@twins>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Merge reason: Pick up the latest perf fixes
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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We should initialize the module dynamic debug datastructures
only after determining that the module is not loaded yet. This
fixes a bug that introduced in 2.6.35-rc2, where when a trying
to load a module twice, we also load it's dynamic printing data
twice which causes all sorts of nasty issues. Also handle
the dynamic debug cleanup later on failure.
Signed-off-by: Yehuda Sadeh <yehuda@hq.newdream.net>
Signed-off-by: Rusty Russell <rusty@rustcorp.com.au> (removed a #ifdef)
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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Reduces text ~300 bytes of text (woohoo!) in an x86 defconfig
$ size vmlinux*
text data bss dec hex filename
7198526 720112 1366288 9284926 8dad3e vmlinux
7198862 720112 1366288 9285262 8dae8e vmlinux.netdev
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Reduces an x86 defconfig text and data ~2k.
text is smaller, data is larger.
$ size vmlinux*
text data bss dec hex filename
7198862 720112 1366288 9285262 8dae8e vmlinux
7205273 716016 1366288 9287577 8db799 vmlinux.device_h
Uses %pV and struct va_format
Format arguments are verified before printk
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Reduces an x86 defconfig text and data ~55k, .6% smaller.
$ size vmlinux*
text data bss dec hex filename
7205273 716016 1366288 9287577 8db799 vmlinux
7258890 719768 1366288 9344946 8e97b2 vmlinux.master
Uses %pV and struct va_format
Format arguments are verified before printk
The dev_info macro is converted to _dev_info because there are
existing uses of variables named dev_info in the kernel tree
like drivers/net/pcmcia/pcnet_cs.c
A dev_info macro is created to call _dev_info
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Add the ability to print a format and va_list from a structure pointer
Allows __dev_printk to be implemented as a single printk while
minimizing string space duplication.
%pV should not be used without some mechanism to verify the
format and argument use ala __attribute__(format (printf(...))).
Signed-off-by: Joe Perches <joe@perches.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: David S. Miller <davem@davemloft.net>
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In slab, all __xxx_track_caller is defined on CONFIG_DEBUG_SLAB || CONFIG_TRACING,
thus caller tracking function should be worked for CONFIG_TRACING. But if
CONFIG_DEBUG_SLAB is not set, include/linux/slab.h will define xxx_track_caller to
__xxx() without consideration of CONFIG_TRACING. This will break the caller tracking
behaviour then.
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Matt Mackall <mpm@selenic.com>
Cc: Vegard Nossum <vegard.nossum@gmail.com>
Cc: Dmitry Monakhov <dmonakhov@openvz.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Acked-by: David Rientjes <rientjes@google.com>
Signed-off-by: Xiaotian Feng <dfeng@redhat.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
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This adds support for MELPAS MCS5000/MSC5080 touch key controllers.
Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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Tested-by: Anatolij Gustschin <agust@denx.de>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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git://git.kernel.org/pub/scm/linux/kernel/git/kaber/nf-next-2.6
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Fix kernel-doc warnings in linux/net.h:
Warning(include/linux/net.h:151): No description found for parameter 'wq'
Warning(include/linux/net.h:151): Excess struct/union/enum/typedef member 'fasync_list' description in 'socket'
Warning(include/linux/net.h:151): Excess struct/union/enum/typedef member 'wait' description in 'socket'
Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Reducing real_num_queues needs to flush the qdisc otherwise
skbs with queue_mappings greater then real_num_tx_queues can
be sent to the underlying driver.
The flow for this is,
dev_queue_xmit()
dev_pick_tx()
skb_tx_hash() => hash using real_num_tx_queues
skb_set_queue_mapping()
...
qdisc_enqueue_root() => enqueue skb on txq from hash
...
dev->real_num_tx_queues -= n
...
sch_direct_xmit()
dev_hard_start_xmit()
ndo_start_xmit(skb,dev) => skb queue set with old hash
skbs are enqueued on the qdisc with skb->queue_mapping set
0 < queue_mappings < real_num_tx_queues. When the driver
decreases real_num_tx_queues skb's may be dequeued from the
qdisc with a queue_mapping greater then real_num_tx_queues.
This fixes a case in ixgbe where this was occurring with DCB
and FCoE. Because the driver is using queue_mapping to map
skbs to tx descriptor rings we can potentially map skbs to
rings that no longer exist.
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Tested-by: Ross Brattain <ross.b.brattain@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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When calling qdisc_reset() the qdisc lock needs to be held. In
this case there is at least one driver i4l which is using this
without holding the lock. Add the locking here.
Signed-off-by: John Fastabend <john.r.fastabend@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip
* 'sched-fixes-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/linux-2.6-tip:
sched: Cure nr_iowait_cpu() users
init: Fix comment
init, sched: Fix race between init and kthreadd
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WQ_SINGLE_CPU combined with @max_active of 1 is used to achieve full
ordering among works queued to a workqueue. The same can be achieved
using WQ_UNBOUND as unbound workqueues always use the gcwq for
WORK_CPU_UNBOUND. As @max_active is always one and benefits from cpu
locality isn't accessible anyway, serving them with unbound workqueues
should be fine.
Drop WQ_SINGLE_CPU support and use WQ_UNBOUND instead. Note that most
single thread workqueue users will be converted to use multithread or
non-reentrant instead and only the ones which require strict ordering
will keep using WQ_UNBOUND + @max_active of 1.
Signed-off-by: Tejun Heo <tj@kernel.org>
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This patch implements unbound workqueue which can be specified with
WQ_UNBOUND flag on creation. An unbound workqueue has the following
properties.
* It uses a dedicated gcwq with a pseudo CPU number WORK_CPU_UNBOUND.
This gcwq is always online and disassociated.
* Workers are not bound to any CPU and not concurrency managed. Works
are dispatched to workers as soon as possible and the only applied
limitation is @max_active. IOW, all unbound workqeueues are
implicitly high priority.
Unbound workqueues can be used as simple execution context provider.
Contexts unbound to any cpu are served as soon as possible.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Arjan van de Ven <arjan@linux.intel.com>
Cc: David Howells <dhowells@redhat.com>
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In preparation of WQ_UNBOUND addition, make the following changes.
* Add WORK_CPU_* constants for pseudo cpu id numbers used (currently
only WORK_CPU_NONE) and use them instead of NR_CPUS. This is to
allow another pseudo cpu id for unbound cpu.
* Reorder WQ_* flags.
* Make workqueue_struct->cpu_wq a union which contains a percpu
pointer, regular pointer and an unsigned long value and use
kzalloc/kfree() in UP allocation path. This will be used to
implement unbound workqueues which will use only one cwq on SMPs.
* Move alloc_cwqs() allocation after initialization of wq fields, so
that alloc_cwqs() has access to wq->flags.
* Trivial relocation of wq local variables in freeze functions.
These changes don't cause any functional change.
Signed-off-by: Tejun Heo <tj@kernel.org>
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libata has two concurrency related limitations.
a. ata_wq which is used for polling PIO has single thread per CPU. If
there are multiple devices doing polling PIO on the same CPU, they
can't be executed simultaneously.
b. ata_aux_wq which is used for SCSI probing has single thread. In
cases where SCSI probing is stalled for extended period of time
which is possible for ATAPI devices, this will stall all probing.
#a is solved by increasing maximum concurrency of ata_wq. Please note
that polling PIO might be used under allocation path and thus needs to
be served by a separate wq with a rescuer.
#b is solved by using the default wq instead and achieving exclusion
via per-port mutex.
Signed-off-by: Tejun Heo <tj@kernel.org>
Acked-by: Jeff Garzik <jgarzik@pobox.com>
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Allows us to track each process that requests and completes events.
Signed-off-by: Jesse Barnes <jbarnes@virtuousgeek.org>
Signed-off-by: Dave Airlie <airlied@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev
* 'upstream-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jgarzik/libata-dev:
ata_generic: implement ATA_GEN_* flags and force enable DMA on MBP 7,1
ahci,ata_generic: let ata_generic handle new MBP w/ MCP89
libahci: Fix bug in storing EM messages
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git://git.kernel.org/pub/scm/linux/kernel/git/linville/wireless-next-2.6
Conflicts:
drivers/net/wireless/libertas/host.h
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This reverts commit 81bdf5bd7349bd4523538cbd7878f334bc2bfe14, which is
obsoleted by commit f350a0a87374 from the net tree.
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For yet unknown reason, MCP89 on MBP 7,1 doesn't work w/ ahci under
linux but the controller doesn't require explicit mode setting and
works fine with ata_generic. Make ahci ignore the controller on MBP
7,1 and let ata_generic take it for now.
Reported in bko#15923.
https://bugzilla.kernel.org/show_bug.cgi?id=15923
NVIDIA is investigating why ahci mode doesn't work.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Peer Chen <pchen@nvidia.com>
Cc: stable@kernel.org
Reported-by: Anders Østhus <grapz666@gmail.com>
Reported-by: Andreas Graf <andreas_graf@csgraf.de>
Reported-by: Benoit Gschwind <gschwind@gnu-log.net>
Reported-by: Damien Cassou <damien.cassou@gmail.com>
Reported-by: tixetsal@juno.com
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>
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git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6
* 'drm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/airlied/drm-2.6: (27 commits)
drm/radeon/kms: remove rv100 bios connector quirk
drm/radeon/kms/pm: fix power state indexing on igp chips in dynpm mode
DRM / radeon / KMS: Fix hibernation regression related to radeon PM (was: Re: [Regression, post-2.6.34] Hibernation broken on machines with radeon/KMS and r300)
drm/radeon/kms/igp: fix possible divide by 0 in bandwidth code (v2)
drm/radeon: add quirk to make HP nx6125 laptop resume.
drm/radeon/kms: add some missing regs to evergreen gpu init
drm/radeon/kms: fix typos in evergreen command checker
drm/radeon/kms: avoid oops on mac r4xx cards
fb: fix colliding defines for fb flags.
drm/radeon/kms: Force HDP_NONSURF to maximum size
drm/radeon/kms: disable frac fb dividers for rs6xx
drm/radeon/kms: don't read attempt to read bios from VRAM on unposted GPU.
drm/radeon/kms: fix typo in evergreen_gpu_init
drm/radeon/kms: return ret in cursor_set failure path
drm/ttm: non pooled page allocation should have GFP_USER set
drm/radeon/r100/r200: fix calculation of compressed cube maps
drm/radeon/r200: handle more hw tex coord types
drm/radeon/kms: CS checker texture fixes for r1xx/r2xx/r3xx
drm/radeon: add fake RN50 table for powerpc
drm/fb: Fix video= mode computation
...
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Commit 0224cf4c5e (sched: Intoduce get_cpu_iowait_time_us())
broke things by not making sure preemption was indeed disabled
by the callers of nr_iowait_cpu() which took the iowait value of
the current cpu.
This resulted in a heap of preempt warnings. Cure this by making
nr_iowait_cpu() take a cpu number and fix up the callers to pass
in the right number.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Arjan van de Ven <arjan@infradead.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky@gmail.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Maxim Levitsky <maximlevitsky@gmail.com>
Cc: Len Brown <len.brown@intel.com>
Cc: Pavel Machek <pavel@ucw.cz>
Cc: Jiri Slaby <jslaby@suse.cz>
Cc: linux-pm@lists.linux-foundation.org
LKML-Reference: <1277968037.1868.120.camel@laptop>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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Conflicts:
fs/fs-writeback.c
Merge reason: Resolve the conflict
Note, i picked the version from Linus's tree, which effectively reverts
the fs-writeback.c bits of:
b97181f: fs: remove all rcu head initializations, except on_stack initializations
As the upstream changes to this file changed this code heavily and the
first attempt to resolve the conflict resulted in a non-booting kernel.
It's safer to re-try this portion of the commit cleanly.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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When I added the flags I must have been using a 25 line terminal and missed the following flags.
The collided with flag has one user in staging despite being in-tree for 5 years.
I'm happy to push this via my drm tree unless someone really wants to do it.
Signed-off-by: Dave Airlie <airlied@redhat.com>
Cc: stable@kernel.org
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Many NICs use an indirection table to map an RX flow hash value to one
of an arbitrary number of queues (not necessarily a power of 2). It
can be useful to remove some queues from this indirection table so
that they are only used for flows that are specifically filtered
there. It may also be useful to weight the mapping to account for
user processes with the same CPU-affinity as the RX interrupts.
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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ethtool_op_set_flags() does not check for unsupported flags, and has
no way of doing so. This means it is not suitable for use as a
default implementation of ethtool_ops::set_flags.
Add a 'supported' parameter specifying the flags that the driver and
hardware support, validate the requested flags against this, and
change all current callers to pass this parameter.
Change some other trivial implementations of ethtool_ops::set_flags to
call ethtool_op_set_flags().
Signed-off-by: Ben Hutchings <bhutchings@solarflare.com>
Reviewed-by: Stanislaw Gruszka <sgruszka@redhat.com>
Acked-by: Jeff Garzik <jgarzik@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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add fast path for in-order fragments
As the fragments are sent in order in most of OSes, such as Windows, Darwin and
FreeBSD, it is likely the new fragments are at the end of the inet_frag_queue.
In the fast path, we check if the skb at the end of the inet_frag_queue is the
prev we expect.
Signed-off-by: Changli Gao <xiaosuo@gmail.com>
----
include/net/inet_frag.h | 1 +
net/ipv4/ip_fragment.c | 12 ++++++++++++
net/ipv6/reassembly.c | 11 +++++++++++
3 files changed, 24 insertions(+)
Signed-off-by: David S. Miller <davem@davemloft.net>
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/proc/net/snmp and /proc/net/netstat expose SNMP counters.
Width of these counters is either 32 or 64 bits, depending on the size
of "unsigned long" in kernel.
This means user program parsing these files must already be prepared to
deal with 64bit values, regardless of user program being 32 or 64 bit.
This patch introduces 64bit snmp values for IPSTAT mib, where some
counters can wrap pretty fast if they are 32bit wide.
# netstat -s|egrep "InOctets|OutOctets"
InOctets: 244068329096
OutOctets: 244069348848
Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Some controllers (KW, Dove) limits the TX IP/layer4 checksum offloading to a max size.
Signed-off-by: Saeed Bishara <saeed@marvell.com>
Acked-by: Lennert Buytenhek <buytenh@wantstofly.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
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'Shoul' must be 'should'.
Signed-off-by: Kulikov Vasiliy <segooon@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Signed-off-by: Gertjan van Wingerde <gwingerde@gmail.com>
Signed-off-by: Ivo van Doorn <IvDoorn@gmail.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
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Determine the size of the xfrm_mark struct, not of its pointer.
Signed-off-by: Andreas Steffen <andreas.steffen@strongswan.org>
Acked-by: Jamal Hadi Salim <hadi@cyberus.ca>
Signed-off-by: David S. Miller <davem@davemloft.net>
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Otherwise we may run into following:
drivers/platform/built-in.o: In function `i8042_lock_chip':
/home/test/ws2/projects/linux-2.6/include/linux/i8042.h:50: multiple definition of `i8042_lock_chip'
drivers/input/serio/built-in.o:/home/test/ws2/projects/linux-2.6/include/linux/i8042.h:50: first defined here
...
make[1]: *** [drivers/built-in.o] Error 1
make: *** [drivers] Error 2
Signed-off-by: Feng Tang <feng.tang@intel.com>
Signed-off-by: Dmitry Torokhov <dtor@mail.ru>
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A __naked function is defined in C but with a body completely implemented
by asm(), including any prologue and epilogue. These asm() bodies expect
standard calling conventions for parameter passing. Older GCCs implement
that correctly, but 4.[56] currently do not, see GCC PR44290. In the
Linux kernel this breaks ARM, causing most arch/arm/mm/copypage-*.c
modules to get miscompiled, resulting in kernel crashes during bootup.
Part of the kernel fix is to augment the __naked function attribute to
also imply noinline and noclone. This patch implements that, and has been
verified to fix boot failures with gcc-4.5 compiled 2.6.34 and 2.6.35-rc1
kernels. The patch is a no-op with older GCCs.
Signed-off-by: Mikael Pettersson <mikpe@it.uu.se>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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* 'for-linus' of git://git.kernel.dk/linux-2.6-block:
block: Don't count_vm_events for discard bio in submit_bio.
cfq: fix recursive call in cfq_blkiocg_update_completion_stats()
cfq-iosched: Fixed boot warning with BLK_CGROUP=y and CFQ_GROUP_IOSCHED=n
cfq: Don't allow queue merges for queues that have no process references
block: fix DISCARD_BARRIER requests
cciss: set SCSI max cmd len to 16, as default is wrong
cpqarray: fix two more wrong section type
cpqarray: fix wrong __init type on pci probe function
drbd: Fixed a race between disk-attach and unexpected state changes
writeback: fix pin_sb_for_writeback
writeback: add missing requeue_io in writeback_inodes_wb
writeback: simplify and split bdi_start_writeback
writeback: simplify wakeup_flusher_threads
writeback: fix writeback_inodes_wb from writeback_inodes_sb
writeback: enforce s_umount locking in writeback_inodes_sb
writeback: queue work on stack in writeback_inodes_sb
writeback: fix writeback completion notifications
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list_for_each_entry_safe is not suitable to protect against concurrent
modification of the list. 6754af6 introduced a race in sb walking.
list_for_each_entry can use the trick of pinning the current entry in
the list before we drop and retake the lock because it subsequently
follows cur->next. However list_for_each_entry_safe saves n=cur->next
for following before entering the loop body, so when the lock is
dropped, n may be deleted.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Cc: Christoph Hellwig <hch@infradead.org>
Cc: John Stultz <johnstul@us.ibm.com>
Cc: Frank Mayhar <fmayhar@google.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
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No logic changes, only spelling.
Signed-off-by: Michael Neuling <mikey@neuling.org>
Cc: linuxppc-dev@ozlabs.org
Cc: David Howells <dhowells@redhat.com>
Cc: Peter Zijlstra <peterz@infradead.org>
LKML-Reference: <15249.1277776921@neuling.org>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
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This patch implements cpu intensive workqueue which can be specified
with WQ_CPU_INTENSIVE flag on creation. Works queued to a cpu
intensive workqueue don't participate in concurrency management. IOW,
it doesn't contribute to gcwq->nr_running and thus doesn't delay
excution of other works.
Note that although cpu intensive works won't delay other works, they
can be delayed by other works. Combine with WQ_HIGHPRI to avoid being
delayed by other works too.
As the name suggests this is useful when using workqueue for cpu
intensive works. Workers executing cpu intensive works are not
considered for workqueue concurrency management and left for the
scheduler to manage.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
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This patch implements high priority workqueue which can be specified
with WQ_HIGHPRI flag on creation. A high priority workqueue has the
following properties.
* A work queued to it is queued at the head of the worklist of the
respective gcwq after other highpri works, while normal works are
always appended at the end.
* As long as there are highpri works on gcwq->worklist,
[__]need_more_worker() remains %true and process_one_work() wakes up
another worker before it start executing a work.
The above two properties guarantee that works queued to high priority
workqueues are dispatched to workers and start execution as soon as
possible regardless of the state of other works.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
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Implement the following utility APIs.
workqueue_set_max_active() : adjust max_active of a wq
workqueue_congested() : test whether a wq is contested
work_cpu() : determine the last / current cpu of a work
work_busy() : query whether a work is busy
* Anton Blanchard fixed missing ret initialization in work_busy().
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Anton Blanchard <anton@samba.org>
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This patch makes changes to make new workqueue features available to
its users.
* Now that workqueue is more featureful, there should be a public
workqueue creation function which takes paramters to control them.
Rename __create_workqueue() to alloc_workqueue() and make 0
max_active mean WQ_DFL_ACTIVE. In the long run, all
create_workqueue_*() will be converted over to alloc_workqueue().
* To further unify access interface, rename keventd_wq to system_wq
and export it.
* Add system_long_wq and system_nrt_wq. The former is to host long
running works separately (so that flush_scheduled_work() dosen't
take so long) and the latter guarantees any queued work item is
never executed in parallel by multiple CPUs. These will be used by
future patches to update workqueue users.
Signed-off-by: Tejun Heo <tj@kernel.org>
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Define WQ_MAX_ACTIVE and create keventd with max_active set to half of
it which means that keventd now can process upto WQ_MAX_ACTIVE / 2 - 1
works concurrently. Unless some combination can result in dependency
loop longer than max_active, deadlock won't happen and thus it's
unnecessary to check whether current_is_keventd() before trying to
schedule a work. Kill current_is_keventd().
(Lockdep annotations are broken. We need lock_map_acquire_read_norecurse())
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Christoph Lameter <cl@linux-foundation.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Oleg Nesterov <oleg@redhat.com>
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Instead of creating a worker for each cwq and putting it into the
shared pool, manage per-cpu workers dynamically.
Works aren't supposed to be cpu cycle hogs and maintaining just enough
concurrency to prevent work processing from stalling due to lack of
processing context is optimal. gcwq keeps the number of concurrent
active workers to minimum but no less. As long as there's one or more
running workers on the cpu, no new worker is scheduled so that works
can be processed in batch as much as possible but when the last
running worker blocks, gcwq immediately schedules new worker so that
the cpu doesn't sit idle while there are works to be processed.
gcwq always keeps at least single idle worker around. When a new
worker is necessary and the worker is the last idle one, the worker
assumes the role of "manager" and manages the worker pool -
ie. creates another worker. Forward-progress is guaranteed by having
dedicated rescue workers for workqueues which may be necessary while
creating a new worker. When the manager is having problem creating a
new worker, mayday timer activates and rescue workers are summoned to
the cpu and execute works which might be necessary to create new
workers.
Trustee is expanded to serve the role of manager while a CPU is being
taken down and stays down. As no new works are supposed to be queued
on a dead cpu, it just needs to drain all the existing ones. Trustee
continues to try to create new workers and summon rescuers as long as
there are pending works. If the CPU is brought back up while the
trustee is still trying to drain the gcwq from the previous offlining,
the trustee will kill all idles ones and tell workers which are still
busy to rebind to the cpu, and pass control over to gcwq which assumes
the manager role as necessary.
Concurrency managed worker pool reduces the number of workers
drastically. Only workers which are necessary to keep the processing
going are created and kept. Also, it reduces cache footprint by
avoiding unnecessarily switching contexts between different workers.
Please note that this patch does not increase max_active of any
workqueue. All workqueues can still only process one work per cpu.
Signed-off-by: Tejun Heo <tj@kernel.org>
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With gcwq managing all the workers and work->data pointing to the last
gcwq it was on, non-reentrance can be easily implemented by checking
whether the work is still running on the previous gcwq on queueing.
Implement it.
Signed-off-by: Tejun Heo <tj@kernel.org>
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To implement non-reentrant workqueue, the last gcwq a work was
executed on must be reliably obtainable as long as the work structure
is valid even if the previous workqueue has been destroyed.
To achieve this, work->data will be overloaded to carry the last cpu
number once execution starts so that the previous gcwq can be located
reliably. This means that cwq can't be obtained from work after
execution starts but only gcwq.
Implement set_work_{cwq|cpu}(), get_work_[g]cwq() and
clear_work_data() to set work data to the cpu number when starting
execution, access the overloaded work data and clear it after
cancellation.
queue_delayed_work_on() is updated to preserve the last cpu while
in-flight in timer and other callers which depended on getting cwq
from work after execution starts are converted to depend on gcwq
instead.
* Anton Blanchard fixed compile error on powerpc due to missing
linux/threads.h include.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Anton Blanchard <anton@samba.org>
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