Hi, We'd like to propose this patchset (ftrace based scsi tracing) as the first attempt for SCSI tracing, starting with the minimum trace points. Tracing gives us an idea how far SCSI processing goes, for example, even in a case that a SCSI IRQ handling is blocked by other drivers that disable interrupts for a long time. Also, trace could be used for debugging purpose in development similar to how USB developers use usbmon for collecting submitted and completed URBs for debugging. In a mission critical area, there is sometimes a case that we have to analyze a problem at customers without taking a memory dump as much as possible. There is also a case to solve a problem which reproducibility is very low (but we can not just leave the problem) so collecting additional data afterwards is difficult. In this version, it prints host#, channel, id, lun, and CDB (and a value of 'result' if it's called in scsi_done().) All fields of CDB are printed in hex, and some of them are printed in ascii as well. That makes the outputs be more user-friendly. For example, retrieving 'lba' and 'transfer length (txlen)' data from CDB of "SCSI3 block command READ/WRITE," and printing them in the friendly format, users can easily correlate the info from SCSI layer with block layer. (All the conversions to ascii that requires relatively large costs are done in TP_printk(), making the overheads at storing trace be minimum.) CDB has various lengths for its size and that made us end up creating __print_hex(). This patchset applies to 2.6.33-rc4. ([PATCH 0/2] scsi: ftrace based scsi tracing feature) [PATCH 1/2] scsi: add __print_hex() to ftrace [PATCH 2/2] scsi: add scsi trace core function and put trace points Thanks, Kei -- To unsubscribe from this list: send the line "unsubscribe linux-scsi" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
