On 13-04-18 01:07 PM, Mathieu Desnoyers wrote: > * Alexandre Montplaisir ([email protected]) wrote: >> On 13-04-18 02:11 AM, Amit Margalit wrote: >>> Hi, >>> >>> Thank for the quick response. Here is the missing data: >>> >>> UST >>> 2.6.32.12-205 (I had to make a tiny patch to make it compile) >>> MemTotal: 24628852 kB >>> lttng-ust-2.1.2 >>> lttng-tools-2.1.1 >>> lttng-modules-2.1.1 >>> babeltrace-1.1.0 >>> userspace-rcu-0.7.6 >>> >>> Which patch for 4MB? >> Hi, >> >> Not sure if it's specifically this one that Matthew was talking about, >> but we have such a patch in the PPA packages. See: >> http://bazaar.launchpad.net/~lttng/lttng-tools/packaging-daily/view/head:/patches/0002-Increase-default-subbuffer-size-to-4MB.patch > First, it should be noted that lttng enable-channel allow overriding the > subbuffer size.
True that. But the value needs to be a power of two (which is not immediately obvious to new users). And if it's not exactly a power of two, it gets rejected, instead of simply rounding to the closest one. We have a patch for that too. ;) > It should be noted that lttng-modules 2.2 is going to output even _more_ > events, so I don't think just making the buffers larger by default is > the right approach. If it's gonna output more events, don't we want larger sizes? > > I think we need to port the "loglevel" from UST to lttng-modules ASAP, > and assign a "debug" loglevel to events we don't care about by default. This sounds like a good idea. My main concern was that most users don't read the man pages, don't fiddle with custom flags, etc. They just run enable-event -a, then start tracing. In this setup, they should not expect dropped events. Cheers, Alex > > Thoughts ? > > Thanks, > > Mathieu > >>> Thanks, >>> >>> Amit Margalit >>> IBM XIV - Storage Reinvented >>> XIV-NAS Development Team >>> Tel. 03-689-7774 >>> Fax. 03-689-7230 >>> >>> >>> >>> From: Matthew Khouzam <[email protected]> >>> To: <[email protected]> >>> Date: 04/15/2013 05:24 PM >>> Subject: Re: [lttng-dev] Limitations on subbuf_size / num_subbuf? >>> >>> >>> >>> Not at all a n00b question, but could you give some more info? what is >>> your version of LTTng tools, are you using UST or kernel tracing? How much >>> ram is on your system? Kernel version? >>> >>> I actually have the patched lttng that has standard subbuffer sizes of 4 >>> mb, so I have not personnaly seen that problem. But the first thing I >>> would do is upgrade to the latest stable. >>> >>> On 13-04-14 06:49 AM, Amit Margalit wrote: >>> Hello, >>> >>> Sorry for the noob question. I seem to be unable to define the total of >>> subbuf_size * num_subbuf higher than 4MB. I am getting ~30% discarded >>> tracepoint data. >>> >>> Any assistance would be greatly appreciated. >>> >>> Amit Margalit >>> IBM XIV - Storage Reinvented >>> XIV-NAS Development Team >>> Tel. 03-689-7774 >>> Fax. 03-689-7230 >> >> _______________________________________________ >> 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
