On 09/18/2014 11:07 AM, Pawel Moll wrote: > On Thu, 2014-09-18 at 16:02 +0100, Christopher Covington wrote: >> Hi Pawel, >> >> On 09/18/2014 10:34 AM, Pawel Moll wrote: >>> Greetings, >>> >>> This is a second spin of the short series posted last week: >>> >>> http://www.spinics.net/lists/kernel/msg1824419.html >>> >>> The first patch adds an additional timestamp field in the perf >>> sample data, which can be requested for any perf event along >>> with normal PERF_SAMPLE_TIME. Events with both values appearing >>> periodically in the perf data allow user code to translate >>> raw monotonic time (obtained via POSIX clock API) to sched_clock >>> domain. Although any perf event can be used, the natural choice >>> would be a sched_switch trace event (for processes with root >>> permissions) or a hrtimer-based PERF_COUNT_SW_CPU_CLOCK. >>> >>> It didn't attract any comments previously, so is just re-posted >>> without any changes. >>> >>> The second patch, functionally orthogonal but complementing >>> the first one, builds on the ftrace "trace_maker" idea. It adds >>> a ioctl that can be used to inject a userspace-generated data >>> into the perf buffer. It provides base for printf-like >>> functionality in perf world. If used with the previous patch, >>> it can be also used to provide synchronisation points for sched >>> vs. raw monotonic time stamps correlation. >>> >>> First version of the patch was taking a zero-terminated string >>> as an argument. Now it is taking a custom structure with "type" >>> and "size" integer fields followed by data. Type value "0" >>> is defined as a zero-terminated string (although size, including >>> the NULL character, must still be provided), but meaning of data >>> for other types is of no interest for the kernel. The intention >>> is to host a list of "well known" types (with reference parsers >>> for them) in the user perf tool code. >> >> Would it be possible for you to also update the corresponding man pages? >> >> https://www.kernel.org/doc/man-pages/ > > I must admit I haven't thought of that, but of course - if the changes > are accepted I'll send patches to the perf_event_open(2) man page. Any > others you had in mind? Nope--reading that page and trying out examples is pretty much how I learned to use perf events. Another great Vince Weaver perf events contribution is the test suite, if you're not already using it. https://github.com/deater/perf_event_tests Christopher -- Employee of Qualcomm Innovation Center, Inc. Qualcomm Innovation Center, Inc. is a member of Code Aurora Forum, hosted by the Linux Foundation. -- 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
