Messages in this thread | | | Date | Wed, 15 Dec 2010 10:54:11 +0530 | From | "Suzuki K. Poulose" <> | Subject | Re: [RFC] [Patch 0/21] Non disruptive application core dump infrastructure |
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On Wed, 15 Dec 2010 10:04:37 +0900 KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:
> On Tue, 14 Dec 2010 15:22:59 +0530 > "Suzuki K. Poulose" <suzuki@in.ibm.com> wrote: > > > Hi all, > > > > This is series of patches implementing an infrastructure for capturing the core > > of an application without disrupting its process semantics. > > > > The infrastructure makes use of the freezer subsystem in kernel to freeze the > > threads and then collect the information to generate the core. > > > > The interface is provided by a /proc/pid/core file, reading which can give the > > ELF formatted core of the process with "pid". The interface supports "seek" > > operation on the fd, allowing the dumper to have control on the data that is > > being dumped. Also it allows the user to store the dump at any location. > > > > The current implementation supports both native as well as the compat ELF > > tasks. > > > > An open() call to the /proc/pid/core will try to freeze the threads in the > > process and the read() requests will dynamically generate the contents for the > > core file. The ELF header & Program Headers are stored in a kernel buffer to > > allow us to map the fpos to the required data section. > > > > In case a thread is not frozen within a time interval, after issuing the freeze > > request, we fill the register state information with 0's to indicate we could > > not capture the data. > > > > A close() would kick the threads out of the refrigerator(). > > > > > > The implementation reuses some of the existing ELF core generation code by > > exporting them. Some of the code common to both native and compat ELF class > > support has been moved to a common place, elfcore-common.c. Also some of the > > reusable functions, specific to the ELF class handling, has been made global, > > after renaming the compat version of the same. > > > > We also added a new API -elf_core_copy_extra_phdrs() -for "reading" the arch > > specific program headers, versus the existing elf_core_write_extra_phdrs(). > > > > Patches 1 to 9 deals with re-arranging the ELF code to be reusable by the > > infrastructure. > > > > Patches 10 to 21 implements the infrastructure. > > > > TODO: Add support for collecting the arch specific notes, currently used only > > by Cell platform. > > > > Please let me know your review comments / thoughts. > > > > Your purpose of this patch is to debug an application without attaching to gdb > or take coredump by gcore ?
The purpose is to take the coredump in a more reliable way without affecting the process semantics. > > IIUC, "freeze" is a bit dangerous because no one can ends the application while > it's freezed and there is no information "it's frozen" via usaual user commands > as 'ps' or 'top'. > > Can you add a new freeze state where the application can get SIGKILL, > at least ? and show task's state as "frozen" in some way ? as > task_state_array[] shows it in /proc/<pid>/status I will investigate this approach.
Thanks Suzuki
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