Selective core dump in Linux - How can I select the dumped sections?
Question：
I am looking for a way to select the sections and memory regions included in a core dump.My application’s core dump size is about 30GB, most of it is in preallocated buffers which I don’t even need in debugging (and can be zeroed later). However, since the dump is so big, it takes too much time for the application to finish crashing and begin recovery.
Can anyone think of a way to select in advance which segments will be in the core dump? Thanks
Answer:
According to the core(5) manpage, you can set which mappings are written to the core file:
Since kernel 2.6.23, the Linux-specific /proc/PID/coredump_filter file can be used to control which memory segments are written to the core dump file in the event that a core dump is performed for the process with the corresponding process ID.
The value in the file is a bit mask of memory mapping types (see mmap(2)). If a bit is set in the mask, then memory mappings of the corresponding type are dumped; otherwise they are not dumped. The bits in this file have the following meanings:
bit 0 Dump anonymous private mappings. bit 1 Dump anonymous shared mappings. bit 2 Dump file-backed private mappings. bit 3 Dump file-backed shared mappings. bit 4 (since Linux 2.6.24) Dump ELF headers. bit 5 (since Linux 2.6.28) Dump private huge pages. bit 6 (since Linux 2.6.28) Dump shared huge pages.
By default, the following bits are set: 0, 1, 4 (if the CONFIG_CORE_DUMP_DEFAULT_ELF_HEADERS kernel configuration option is enabled), and 5. The value of this file is displayed in hexadecimal. (The default value is thus displayed as 33.) Memory-mapped I/O pages such as frame buffer are never dumped, and virtual DSO pages are always dumped, regardless of the coredump_filter value. … This file is only provided if the kernel was built with the CONFIG_ELF_CORE configuration option.
for example you can $(echo 1 > /proc/PID/coredump_filter )
