On Mon, Mar 10, 2025 at 01:29:26PM +0000, Suzuki Kuruppassery Poulose wrote: > Hi Leo > > On 10/03/2025 10:49, Leo Yan wrote: > > Add an attribute for updating buffer when the AUX trace is paused. And > > populate the value to the 'update_buf_on_pause' flag during the AUX > > setting up. > > Do we need this attribute in the uAPI ? This uAPI allows users to perform AUX pause and resume without the long latency caused by copying hardware trace data. E.g., a user can specify a large AUX buffer size using option "-m,128M". If the buffer is considered large enough to accommodate hardware trace data for a small program, the 'update_buf_on_pause' flag can be set to false, the copying will be deferred until the end of the perf session. I am bias to keep this uAPI. If you prefer to remove it, I am also fine with that. > Could we do this by default for > sinks without interrupt ? This definitely improves the quality of trace > collected for such sinks and the driver can transparently do this. How about we dynamically set the default flag in the Perf tool? - If users set explictly the 'update_buf_on_pause' flag, then the setting will be respected. - If users don't set the flag, perf tool detects it is TRBE sinks, then it can set 'update_buf_on_pause' flag as false. - If users don't set the flag, perf tool detects it is ETF/ETB/ETR sinks, it sets the flag as true. Thanks, Leo
