Messages in this thread | | | Date | Thu, 19 Dec 2013 16:14:27 +0100 | From | Peter Zijlstra <> | Subject | Re: [PATCH v0 04/71] itrace: Infrastructure for instruction flow tracing units |
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On Thu, Dec 19, 2013 at 04:54:27PM +0200, Alexander Shishkin wrote: > Peter Zijlstra <peterz@infradead.org> writes: > > > On Thu, Dec 19, 2013 at 12:57:59PM +0100, Peter Zijlstra wrote: > > So you're basically forced to stop the tracing on PMI anyhow; so your > > continuous tracing argument goes out the window. > > It's only stopped inside the PMI handler to set up another buffer, and > is then started again, so no useful trace is lost. PMI handler is not > traced. What you're proposing is stopping it for good till perf collects > the previous data, which will lose us a lot of trace. So my argument > stands.
That is not what I proposed at all.
The PMI will swizzle the pages and resume recording. If there is no space in the output buffer, we'll simply re-use the existing pages and overwrite data.
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