Re: [patch 05/24] perfmon: X86 generic code (x86)

[Andi Kleen <andi@firstfloor.org>]

> What if a threads reprograms the counters while another is reading them?

In the worst case you get an invalid event, which is then discarded.
I think. I've never tried to understand it in all details, but 
at least it seems to work.

> How is the buffer reset?

drivers/oprofile/cpu_buffer.c:

/* Resets the cpu buffer to a sane state. */
void cpu_buffer_reset(struct oprofile_cpu_buffer *cpu_buf)
{
        /* reset these to invalid values; the next sample
         * collected will populate the buffer with proper
         * values to initialize the buffer
         */
        cpu_buf->last_is_kernel = -1;
        cpu_buf->last_task = NULL;
}

-Andi

-- 
ak@linux.intel.com