linux-toradex.git/kernel/cpuset.c, branch v2.6.28.9

sched, cpusets: fix warning in kernel/cpuset.c

2008-11-29T19:39:29+00:00

this warning:

  kernel/cpuset.c: In function ‘generate_sched_domains’:
  kernel/cpuset.c:588: warning: ‘ndoms’ may be used uninitialized in this function

triggers because GCC does not recognize that ndoms stays uninitialized
only if doms is NULL - but that flow is covered at the end of
generate_sched_domains().

Help out GCC by initializing this variable to 0. (that's prudent anyway)

Also, this function needs a splitup and code flow simplification:
with 160 lines length it's clearly too long.

Signed-off-by: Ingo Molnar

cpuset: update top cpuset's mems after adding a node

2008-11-20T02:49:58+00:00

After adding a node into the machine, top cpuset's mems isn't updated.

By reviewing the code, we found that the update function

  cpuset_track_online_nodes()

was invoked after node_states[N_ONLINE] changes.  It is wrong because
N_ONLINE just means node has pgdat, and if node has/added memory, we use
N_HIGH_MEMORY.  So, We should invoke the update function after
node_states[N_HIGH_MEMORY] changes, just like its commit says.

This patch fixes it.  And we use notifier of memory hotplug instead of
direct calling of cpuset_track_online_nodes().

Signed-off-by: Miao Xie 
Acked-by: Yasunori Goto 
Cc: David Rientjes 
Cc: Paul Menage 
Signed-off-by: Linus Torvalds

cpuset: fix regression when failed to generate sched domains

2008-11-18T07:44:51+00:00

Impact: properly rebuild sched-domains on kmalloc() failure

When cpuset failed to generate sched domains due to kmalloc()
failure, the scheduler should fallback to the single partition
'fallback_doms' and rebuild sched domains, but now it only
destroys but not rebuilds sched domains.

The regression was introduced by:

| commit dfb512ec4834116124da61d6c1ee10fd0aa32bd6
| Author: Max Krasnyansky 
| Date:   Fri Aug 29 13:11:41 2008 -0700
|
|    sched: arch_reinit_sched_domains() must destroy domains to force rebuild

After the above commit, partition_sched_domains(0, NULL, NULL) will
only destroy sched domains and partition_sched_domains(1, NULL, NULL)
will create the default sched domain.

Signed-off-by: Li Zefan 
Cc: Max Krasnyansky 
Cc: 
Signed-off-by: Ingo Molnar

cpuset: use seq_mask_ to print masks

2008-10-20T15:52:39+00:00

1) seq_file excepts that m->count == m->size when it's buf is full,
   so current code will causes bugs when buf is overflow.

2) There is not too good that cpuset accesses struct seq_file's
   fields directly.

Signed-off-by: Lai Jiangshan 
Cc: Alexey Dobriyan 
Acked-by: Paul Menage 
Cc: Paul Jackson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpuset.c: remove extra variable

2008-10-20T15:52:39+00:00

Remove the use of int cpus_nonempty variable from 'update_flag' function.

Signed-off-by: Md.Rakib H. Mullick 
Acked-by: Paul Jackson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpusets: scan_for_empty_cpusets(), cpuset doesn't seem to be so const

2008-10-03T11:39:50+00:00

This fixes a warning on latest -tip:

 kernel/cpuset.c: Dans la fonction «scan_for_empty_cpusets» :
 kernel/cpuset.c:1932: attention : passing argument 1 of «list_add_tail» discards qualifiers from pointer target type

Actually the struct cpuset *root passed in parameter to scan_for_empty_cpusets
is not supposed to be const since an entry is added on the tail of its list.
Just correct the qualifier.

Signed-off-by: Frederic Weisbecker 
Signed-off-by: Ingo Molnar

cpuset: avoid changing cpuset's cpus when -errno returned

2008-09-13T21:41:50+00:00

After the patch:

commit 0b2f630a28d53b5a2082a5275bc3334b10373508
Author: Miao Xie 
Date:   Fri Jul 25 01:47:21 2008 -0700

    cpusets: restructure the function update_cpumask() and update_nodemask()

It might happen that 'echo 0 > /cpuset/sub/cpus' returned failure but 'cpus'
has been changed, because cpus was changed before calling heap_init() which
may return -ENOMEM.

This patch restores the orginal behavior.

Signed-off-by: Li Zefan 
Acked-by: Paul Menage 
Cc: Paul Jackson 
Cc: Miao Xie 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

sched, cpuset: rework sched domains and CPU hotplug handling (v4)

2008-08-14T09:23:51+00:00

This is an updated version of my previous cpuset patch on top of
the latest mainline git.
The patch fixes CPU hotplug handling issues in the current cpusets code.
Namely circular locking in rebuild_sched_domains() and unsafe access to
the cpu_online_map in the cpuset cpu hotplug handler.

This version includes changes suggested by Paul Jackson (naming, comments,
style, etc). I also got rid of the separate workqueue thread because it is
now safe to call get_online_cpus() from workqueue callbacks.

Here are some more details:

rebuild_sched_domains() is the only way to rebuild sched domains
correctly based on the current cpuset settings. What this means
is that we need to be able to call it from different contexts,
like cpu hotplug for example.
Also latest scheduler code in -tip now calls rebuild_sched_domains()
directly from functions like arch_reinit_sched_domains().

In order to support that properly we need to rework cpuset locking
rules to avoid circular dependencies, which is what this patch does.
New lock nesting rules are explained in the comments.
We can now safely call rebuild_sched_domains() from virtually any
context. The only requirement is that it needs to be called under
get_online_cpus(). This allows cpu hotplug handlers and the scheduler
to call rebuild_sched_domains() directly.
The rest of the cpuset code now offloads sched domains rebuilds to
a workqueue (async_rebuild_sched_domains()).

This version of the patch addresses comments from the previous review.
I fixed all miss-formated comments and trailing spaces.

I also factored out the code that builds domain masks and split up CPU and
memory hotplug handling. This was needed to simplify locking, to avoid unsafe
access to the cpu_online_map from mem hotplug handler, and in general to make
things cleaner.

The patch passes moderate testing (building kernel with -j 16, creating &
removing domains and bringing cpus off/online at the same time) on the
quad-core2 based machine.

It passes lockdep checks, even with preemptable RCU enabled.
This time I also tested in with suspend/resume path and everything is working
as expected.

Signed-off-by: Max Krasnyansky 
Acked-by: Paul Jackson 
Cc: menage@google.com
Cc: a.p.zijlstra@chello.nl
Cc: vegard.nossum@gmail.com
Signed-off-by: Ingo Molnar

cpuset: clean up cpuset hierarchy traversal code

2008-07-30T16:41:44+00:00

Use cpuset.stack_list rather than kfifo, so we avoid memory allocation
for kfifo.

Signed-off-by: Li Zefan 
Signed-off-by: Lai Jiangshan 
Cc: Paul Menage 
Cc: Cedric Le Goater 
Cc: Balbir Singh 
Cc: KAMEZAWA Hiroyuki 
Cc: Paul Jackson 
Signed-off-by: Andrew Morton 
Signed-off-by: Linus Torvalds

cpuset: fix wrong calculation of relax domain level