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authorFrederic Weisbecker <fweisbec@gmail.com>2014-03-05 17:02:22 +0100
committerFrederic Weisbecker <fweisbec@gmail.com>2014-03-13 15:56:44 +0100
commitdee08a72deefac251267ed2717717596aa8b6818 (patch)
tree33334d1764905dbbac0d795f2086b03d91ebe8da /arch/m32r/include/asm/Kbuild
parentcputime: Bring cputime -> nsecs conversion (diff)
downloadlinux-dev-dee08a72deefac251267ed2717717596aa8b6818.tar.xz
linux-dev-dee08a72deefac251267ed2717717596aa8b6818.zip
cputime: Fix jiffies based cputime assumption on steal accounting
The steal guest time accounting code assumes that cputime_t is based on jiffies. So when CONFIG_NO_HZ_FULL=y, which implies that cputime_t is based on nsecs, steal_account_process_tick() passes the delta in jiffies to account_steal_time() which then accounts it as if it's a value in nsecs. As a result, accounting 1 second of steal time (with HZ=100 that would be 100 jiffies) is spuriously accounted as 100 nsecs. As such /proc/stat may report 0 values of steal time even when two guests have run concurrently for a few seconds on the same host and same CPU. In order to fix this, lets convert the nsecs based steal delta to cputime instead of jiffies by using the right conversion API. Given that the steal time is stored in cputime_t and this type can have a smaller granularity than nsecs, we only account the rounded converted value and leave the remaining nsecs for the next deltas. Reported-by: Huiqingding <huding@redhat.com> Reported-by: Marcelo Tosatti <mtosatti@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Marcelo Tosatti <mtosatti@redhat.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Acked-by: Rik van Riel <riel@redhat.com> Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Diffstat (limited to 'arch/m32r/include/asm/Kbuild')
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