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Re: [Xen-devel] xentrace buffering



pak333@xxxxxxxxxxx wrote:
Hi,

I am looking at the xentrace code and it looks like the individual cores/cpus write their (trace data) into individual regions of memory and they are all collected by xentrace and processed.

I would like to have one trace buffer for all cores so that I *can get an exact sequence in time order* of the events that have occurred over the sampling period across cores/cpus.

Is that easily doable>? If so, any pointers can someone send me pointers as to where I should start looking at modifying.


It's doable, but would require some work. I think the reason for having different buffers for each core is so that the trace code can be really light weight, since it doesn't have to deal with acquiring a write lock, etc.

Theoretically, each core's clock should be very close to all the others, so the timestamp in the trace records should allow a reasonably accurate reconstruction of the order of events.

Rob



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