Red Hat Summit第15章 Configuring kdump on the command line
The memory for kdump is reserved during the system boot. You can configure the memory size in the system’s Grand Unified Bootloader (GRUB) configuration file. The memory size depends on the crashkernel= value specified in the configuration file and the size of the physical memory of system.
15.1. Estimating the kdump size
When planning and building your kdump environment, it is important to know the space required by the crash dump file.
The makedumpfile --mem-usage command estimates the space required by the crash dump file. It generates a memory usage report. The report helps you decide the dump level and the pages that are safe to exclude.
Procedure
Enter the following command to generate a memory usage report:
# makedumpfile --mem-usage /proc/kcore TYPE PAGES EXCLUDABLE DESCRIPTION ------------------------------------------------------------- ZERO 501635 yes Pages filled with zero CACHE 51657 yes Cache pages CACHE_PRIVATE 5442 yes Cache pages + private USER 16301 yes User process pages FREE 77738211 yes Free pages KERN_DATA 1333192 no Dumpable kernel data
The makedumpfile --mem-usage command reports required memory in pages. This means that you must calculate the size of memory in use against the kernel page size.
By default the RHEL kernel uses 4 KB sized pages on AMD64 and Intel 64 CPU architectures, and 64 KB sized pages on IBM POWER architectures.
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