On 9/12/14, 4:48 AM, Pawel Moll wrote:
This patch adds a PERF_COUNT_SW_MARKER event type, which can be requested by user and a PERF_EVENT_IOC_MARKER ioctl command which will inject an event of said type into the perf buffer. The ioctl can take a zero-terminated string argument, similar to tracing_marker in ftrace, which will be kept in the "raw" field of the sample. The main use case for this is synchronisation of performance data generated in user space with the perf stream coming from the kernel. For example, the marker can be inserted by a JIT engine after it generated portion of the code, but before the code is executed for the first time, allowing the post-processor to pick the correct debugging information. Other example is a system profiling tool taking data from other sources than just perf, which generates a marker at the beginning at at the end of the session (also possibly periodically during the session) to synchronise kernel timestamps with clock values obtained in userspace (gtod or raw_monotonic).
Seems really similar to what I proposed in the past: https://lkml.org/lkml/2011/2/27/159 Which was rejected. David -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
