Oh,What I want is something like "lttng enable-event -a -k --function " to enable ALL function trace.
Thanks zhenyu.ren ------------------------------------------------------------------ 发件人：zhenyu.ren <[email protected]> 发送时间：2015年2月18日(星期三) 14:29 收件人：Francis Deslauriers <[email protected]> 抄 送：[email protected] <[email protected]> 主 题：答复：答复：[lttng-dev] Can lttng support kernel function tracer > I think that might be a usecase for a profiler rather than a usecase for a > tracer I am sorry that I have misled you.Not all write instances(a chance in a million) take 100ms+ to complete.So I have to trace all write instances to capture the deviant ones. Thanks zhenyu.ren ------------------------------------------------------------------ 发件人：Francis Deslauriers <[email protected]> 发送时间：2015年2月17日(星期二) 23:09 收件人：zhenyu.ren <[email protected]> 抄 送：[email protected] <[email protected]> 主 题：Re: 答复：[lttng-dev] Can lttng support kernel function tracer CCing lttng-dev back in the thread. I might be wrong but I think that might be a usecase for a profiler rather than a usecase for a tracer. Can someone else confirm? To do that kind of work, you could compile your kernel with gprof support. Thanks, Francis On Tue, Feb 17, 2015 at 3:38 AM, zhenyu.ren <[email protected]> wrote: > Hi,Francis > In fact, I want to trace all kernel functions related to some > behavior.For example,I write() and it returns 100ms later ,so I want to > know which kernel function is too slow. In this case,I can use function > tracer to trace "all" kernel function in the write() time window.However,I > want to know is it possible that lttng can be useful in this case. > > Thanks > zhenyu.ren > > > ------------------------------------------------------------------ > 发件人：Francis Deslauriers <[email protected]> > 发送时间：2015年2月17日(星期二) 00:53 > 收件人：zhenyu.ren <[email protected]> > 抄 送：lttng-dev <[email protected]> > 主 题：Re: [lttng-dev] Can lttng support kernel function tracer > > Hi Zhenyu, > > If I understandd your question correctly, I can think of two ways to > trace an arbitrary kernel function. First, you can hook the tracer on > a dynamic probe[1] using something like this: > "lttng enable-event customEventName -k --probe kernelFunctionName". > You can also hook the tracer on both entry and exit of a function > using "--function" instead of "--probe". > To list your kernel symbols use "cat /proc/kallsyms" > Second, you can create custom kernel tracepoints and compile them in > you kernel. Have a look at the online documentation [2]. > > Don't hesitate to explain further if this doesn't answer your question. > > Cheers! > Francis > > [1] > http://git.lttng.org/?p=lttng-tools.git;a=blob;f=doc/quickstart.txt;h=018c27b2b939ef7cd075255fd01bcfd8b2b21b1e;hb=HEAD#l93 > [2] http://lttng.org/docs/#doc-instrumenting-linux-kernel-itself > > On Thu, Feb 12, 2015 at 7:49 PM, zhenyu.ren <[email protected]> wrote: >> Hi, >> >> It's well known that lttng can make use of kernel tracepoints to do block >> tracing ,system call tracing etc.Is it possible that lttng can produce >> anything like kernel function tracer does? >> >> Thanks >> zhenyu.ren >> >> _______________________________________________ >> lttng-dev mailing list >> [email protected] >> http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev _______________________________________________ lttng-dev mailing list [email protected] http://lists.lttng.org/cgi-bin/mailman/listinfo/lttng-dev
