Low-level device drivers might have additional data which complements blktrace data. For example, zfcp, a SCSI HBA driver, is capable of obtaining additional latency information per request from HBAs. Those latencies allow to further break down the overall D2C request latency provided by blktrace. We propose an additional trace for blktrace, called "driver data". It is a sort of small binary blob, which contains a low-level driver specific struct. Blktrace would be able to filter this trace (-a option) and include it within its binary output. A small device driver specific tool on top of blktrace would then analyze "driver data" traces. Patch 1/3 makes the blktrace kernel code provide blk_add_driver_data() for use by device drivers. Patch 2/3 adds support for driver data traces to blktrace tools. Patch 3/3 makes zfcp provide additional request latency and queue utilization data through blktrace. Patches are against scsi-misc and blktrace git. Martin -- To unsubscribe from this list: send the line "unsubscribe linux-btrace" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
