Hello, (2014/11/04 9:28), Pawel Moll wrote: > 2. User event generation > > Everyone present agreed that it would be a very-nice-to-have feature. > There was some discussion about implementation details, so I welcome > feedback and comments regarding my take on the matter. Hmm, I'm trying to make a similar thing, dynamic event definition via ftrace, which is already done by kprobes/uprobes. And this will be shown as dynamic events from perf too. What I'd like to do is the binary version of ftrace-marker, the text version is already supported by qemu (see below). https://lists.gnu.org/archive/html/qemu-devel/2013-04/msg00505.html But since that is just a string data (not structured data), it is hard to analyze via perf-script or some other useful filters/triggers in ftrace. In my idea, the new event will be defined via a special file in debugfs like kprobe-events, like below. # cd $debugfs/tracing # echo "newgrp/newevent signarg:s32 flag:u64" >> marker_events # cat events/newgrp/newevent/format name: newevent ID: 2048 format: field:unsigned short common_type; offset:0; size:2; signed:0; field:unsigned char common_flags; offset:2; size:1; signed:0; field:unsigned char common_preempt_count; offset:3; size:1;signed:0; field:int common_pid; offset:4; size:4; signed:1; field:s32 signarg; offset:8; size:4; signed:1; field:u64 flag; offset:12; size:8; signed:0; print fmt: "signarg=%d flag=0x%Lx", REC->signarg, REC->flag Then, users will write the data (excluded common fields) when the event happens via trace_marker which start with '\0'ID(in u32). Kernel just checks the ID and its data size, but doesn't parse, filter/trigger it and log it into the kernel buffer. Of course, this has a downside that the user must have a privilege to access to debugfs. Thus maybe we need both of prctl() IF for perf and this IF for ftrace. Thank you, -- Masami HIRAMATSU Software Platform Research Dept. Linux Technology Research Center Hitachi, Ltd., Yokohama Research Laboratory E-mail: masami.hiramatsu.pt@xxxxxxxxxxx -- 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
