Re: [LTP] Patch to record kernel dump message to each testcases log

hake huang
2010-10-13T07:07:53Z

very clear thanks.

2010/10/13 Subrata Modak <subrata@linux.vnet.ibm.com>:
> On Wed, 2010-10-13 at 15:00 +0800, hake huang wrote:
>> Hi Subrata,
>>
>> one question:
>> -K will only record all kernel message, but can not match each testcase, right?
>
> It will record kernel messages for each individual test case by
> recording it inside ltp*/output/<DMESG_DIR_NAME>/<testname>.dmeg
>
> Once test run is over it will delete all .dmeg* files of zero size and
> will retain only those having real entries. So, you will get exactly
> which tests generated kernel messages and what the messages exactly are
> for each individual test.
>
> Regards--
> Subrata
>
>>
>> Regards,
>>
>> Hake
>>
>> 2010/10/13 Subrata Modak <subrata@linux.vnet.ibm.com>:
>> > On Wed, 2010-10-13 at 12:22 +0530, Subrata Modak wrote:
>> >> On Wed, 2010-10-13 at 13:30 +0800, hake huang wrote:
>> >> > 2010/10/13 Garrett Cooper <yanegomi@gmail.com>
>> >> > >
>> >> > > On Tue, Oct 12, 2010 at 9:38 PM, hake huang <hakehuang@gmail.com> wrote:
>> >> > > > Hi
>> >> > > >
>> >> > > > I see this simple solution is no quite fit. But the kernel dump message for
>> >> > > > each test case is necessary for analysing. I can work on this further, with
>> >> > > > below help:
>> >> > > > 1. Where can I find the reason for the IIRC break?
>> >> > >
>> >> > > IIRC -> If I remember correctly.
>> >> > so I need ask Subrata about this problem, right? what is the existing
>> >> > functionality?
>> >>
>> >> I believe the functionality your original patch was proposing is already
>> >> in LTP . I guess they will solve your problem. See the following
>> >> commits:
>> >>
>> >> git show e3bc3758d3e4d17a0e04009ef873df53819b9ec6
>> >> git show bd9d440be1da8020c93ac92e497e3a16e66e9fa3
>> >>
>> >> Just use:
>> >>
>> >> ./runltp -K <DMESG_DIRECTORY_NAME>
>> >
>> > Basically, its a choice given to users who would like to record the
>> > kernel messages, and not forcing recording all kernel messages which
>> > your original patch is proposing :-)
>> >
>> > Regards--
>> > Subrata
>> >
>> >>
>> >> option while running ltp.
>> >>
>> >> Regards--
>> >> Subrata
>> >>
>> >> > >
>> >> > > > 2. Can it  be an option to avoid the size limitation on some embedded
>> >> > > > system?
>> >> > >
>> >> > > No. This is outside the realm of LTP, but we must remain conscious of
>> >> > > the fact that there are folks running LTP on cellphones, etc, where
>> >> > > space is very much a luxury.
>> >> > I see. but why can't they run in quit_mode?
>> >> > >
>> >> > > > 3.  A kind of seperating tag is needed for kernel message, right? e.g
>> >> > > > <kernel_dump_start>dump message<kernel_dump_end>
>> >> > >
>> >> > > I think that adding an optional capture feature might be worthwhile,
>> >> > > but you'll no doubt quickly find with some processes that the dmesg
>> >> > > buffer will fill up quickly.
>> >> > I have seen such events, and such cases need to be checked manually.
>> >> > >
>> >> > > > 4.  I see in ltp-pan.c the file descriptors, terminals are changed in child
>> >> > > > process. if the system(3) has problem, the worst cases is there are no
>> >> > > > kernel messge output in parent process, but the pan can still function well.
>> >> > >
>> >> > > Can you say that with 100% certainty? One of the potential problems
>> >> > > with system is the fact that it allocates a shell and depending on how
>> >> > > processes are executed and how file descriptors are cleaned up,
>> >> > >
>> >> > > Actually, pan makes zero attempts at closing open file descriptors and
>> >> > > the like, so the problem is still very much with pan.
>> >> > >
>> >> > So your concerns is about file descriptors which open in ltp process,
>> >> > I think this is an existing problem. I mean maybe pan need to attempt
>> >> > to close open file descriptors. system(3) only increases the change of
>> >> > occurrence caused by this problem, right?
>> >> > > > if not use system(3), can you give your suggestion on this, exec(3) seems to
>> >> > > > have the same problem as system(3)?
>> >> > >
>> >> > > Yes and no. In this case the problems that exist with open file
>> >> > > descriptor inheritance, etc are unfortunately no worse from that
>> >> > > perspective than your proposed code would do, but there are still
>> >> > > other problems that need to be resolved with your proposed change
>> >> > > anyhow that are much more pressing.
>> >> > >
>> >> > > -Garrett
>> >>
>> >>
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