Skip to content

L
linux
Switch branch/tag
  1. 04 Feb, 2009 1 commit
    • Suresh Siddha's avatar
      sched: fix nohz load balancer on cpu offline · 483b4ee6
      Suresh Siddha authored 
      Christian Borntraeger reports:

> After a logical cpu offline, even on a complete idle system, there
> is one cpu with full ticks. It turns out that nohz.cpu_mask has the
> the offlined cpu still set.
>
> In select_nohz_load_balancer() we check if the system is completely
> idle to turn of load balancing. We compare cpu_online_map with
> nohz.cpu_mask.  Since cpu_online_map is updated on cpu unplug,
> but nohz.cpu_mask is not, the check fails and the scheduler believes
> that we need an "idle load balancer" even on a fully idle system.
> Since the ilb cpu does not deactivate the timer tick this breaks NOHZ.

Fix the select_nohz_load_balancer() to not set the nohz.cpu_mask
while a cpu is going offline.
Reported-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarSuresh Siddha <suresh.b.siddha@intel.com>
Tested-by: default avatarChristian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      483b4ee6
  3. 03 Feb, 2009 12 commits
  5. 02 Feb, 2009 23 commits
  7. 01 Feb, 2009 4 commits
    • Linus Torvalds's avatar
      Manually revert "mlock: downgrade mmap sem while populating mlocked regions" · 27421e21
      Linus Torvalds authored 
      This essentially reverts commit 8edb08ca.

It downgraded our mmap semaphore to a read-lock while mlocking pages, in
order to allow other threads (and external accesses like "ps" et al) to
walk the vma lists and take page faults etc.  Which is a nice idea, but
the implementation does not work.

Because we cannot upgrade the lock back to a write lock without
releasing the mmap semaphore, the code had to release the lock entirely
and then re-take it as a writelock.  However, that meant that the caller
possibly lost the vma chain that it was following, since now another
thread could come in and mmap/munmap the range.

The code tried to work around that by just looking up the vma again and
erroring out if that happened, but quite frankly, that was just a buggy
hack that doesn't actually protect against anything (the other thread
could just have replaced the vma with another one instead of totally
unmapping it).

The only way to downgrade to a read map _reliably_ is to do it at the
end, which is likely the right thing to do: do all the 'vma' operations
with the write-lock held, then downgrade to a read after completing them
all, and then do the "populate the newly mlocked regions" while holding
just the read lock.  And then just drop the read-lock and return to user
space.

The (perhaps somewhat simpler) alternative is to just make all the
callers of mlock_vma_pages_range() know that the mmap lock got dropped,
and just re-grab the mmap semaphore if it needs to mlock more than one
vma region.

So we can do this "downgrade mmap sem while populating mlocked regions"
thing right, but the way it was done here was absolutely not correct.
Thus the revert, in the expectation that we will do it all correctly
some day.

Cc: Lee Schermerhorn <lee.schermerhorn@hp.com>
Cc: Rik van Riel <riel@redhat.com>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@kernel.org
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
      27421e21
    • Devin Heitmueller's avatar
      V4L/DVB (10411): s5h1409: Perform s5h1409 soft reset after tuning · 67e70baf
      Devin Heitmueller authored 
      Just like with the s5h1411, the s5h1409 needs a soft-reset in order for it
to know that the tuner has been told to change frequencies.  This change
changes the behavior from "random tuning times between 500ms to complete
tuning lock failures" to "tuning lock consistently within 700ms".

Thanks to Robert Krakora <rob.krakora@messagenetsystems.com> for doing
initial testing of the patch on the KWorld 330U.

Thanks to Andy Walls <awalls@radix.net> for doing testing of the patch on
the HVR-1600.

Thanks to Michael Krufky <mkrufky@linuxtv.org> for doing additional testing.
Signed-off-by: default avatarDevin Heitmueller <dheitmueller@linuxtv.org>
Signed-off-by: default avatarMichael Krufky <mkrufky@linuxtv.org>
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
      67e70baf
    • Mauro Carvalho Chehab's avatar
      V4L/DVB (10403): saa7134-alsa: saa7130 doesn't support digital audio · 40c41c8c
      Mauro Carvalho Chehab authored 
      According with saa7130 public datasheet, saa7130 doesn't support
digital audio. This is also confirmed by experimental tests. So, it
doesn't make sense to let saa7134-alsa register for those chipsets.
Signed-off-by: default avatarMauro Carvalho Chehab <mchehab@redhat.com>
      40c41c8c
    • Rusty Russell's avatar
      sched_rt: don't use first_cpu on cpumask created with cpumask_and · 3d398703
      Rusty Russell authored 
      cpumask_and() only initializes nr_cpu_ids bits, so the (deprecated)
first_cpu() might find one of those uninitialized bits if nr_cpu_ids
is less than NR_CPUS (as it can be for CONFIG_CPUMASK_OFFSTACK).
Signed-off-by: default avatarRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: default avatarIngo Molnar <mingo@elte.hu>
      3d398703
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7