Re: [PATCH v2 3/3] X86: Add a thread cpu time implementation to vDSO

[David Ahern]

On 1/1/15 7:59 PM, Shaohua Li wrote:
> I'm wondering how we could use the perf to implament a clock_gettime.
> reading the perf fd or using ioctl is slow so reading the mmap
> ringbuffer is the only option. But as far as I know the ringbuffer has
> data only when an event is generated. Between two events, there is
> nothing we can read from the ringbuffer. Then how can application get
> time info in the interval?

Are you wanting to read perf_clock from userspace?

David
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