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authorCyril Bur <cyrilbur@gmail.com>2015-02-12 18:01:28 -0500
committerLinus Torvalds <torvalds@linux-foundation.org>2015-02-12 21:54:13 -0500
commit4be1b29795d692d512bb67b770665d6f8ea5cb0b (patch)
tree7502b10178a0c16f65e7be2aecf583691f78dedf /arch/tile/kernel/ptrace.c
parent545a2bf742fb41f17d03486dd8a8c74ad511dec2 (diff)
powerpc: add running_clock for powerpc to prevent spurious softlockup warnings
On POWER8 virtualised kernels the VTB register can be read to have a view of time that only increases while the guest is running. This will prevent guests from seeing time jump if a guest is paused for significant amounts of time. On POWER7 and below virtualised kernels stolen time is subtracted from local_clock as a best effort approximation. This will not eliminate spurious warnings in the case of a suspended guest but may reduce the occurance in the case of softlockups due to host over commit. Bare metal kernels should avoid reading the VTB as KVM does not restore sane values when not executing, the approxmation is fine as host kernels won't observe any stolen time. [akpm@linux-foundation.org: coding-style fixes] Signed-off-by: Cyril Bur <cyrilbur@gmail.com> Cc: Michael Ellerman <mpe@ellerman.id.au> Cc: Andrew Jones <drjones@redhat.com> Acked-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: chai wen <chaiw.fnst@cn.fujitsu.com> Cc: Fabian Frederick <fabf@skynet.be> Cc: Aaron Tomlin <atomlin@redhat.com> Cc: Ben Zhang <benzh@chromium.org> Cc: Martin Schwidefsky <schwidefsky@de.ibm.com> Cc: John Stultz <john.stultz@linaro.org> Cc: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'arch/tile/kernel/ptrace.c')
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