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

From: David Ahern
Date: Fri Jan 02 2015 - 10:31:53 EST


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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