VPP/cpel

CPEL Performance Event Log Files

This page describes the CPEL file format. Over the last decade, we've constructed a set of tools to collect, display and report fine-grained performance event data. As the toolset has grown, limitations inherent in previous file formats have become an issue.

CPEL files consist of a set of sections, similar to ELF-files. Specific tools may or may not understand a particular section. Sections are TLV's: (tag, length, value) tuples. Specific tools can skip or copy sections without needing to know anything about the data therein.

File Format

This table describes the CPEL file format.

Octet offset	Data
0x0	Endian bit (0x80), File Version, 7 bits (0x1...0x7F)
0x1	Unused, 8 bits
0x2-0x3	Number of sections (16 bits) (NSECTIONS)
0x4	File date (32-bits) (POSIX "epoch" format)
0x8	Type of first section (32 bits)
0xC	Length of first section (32 bits), not including type and length
0x10	First section data
NSECTIONS-1, or up to 64K-2 additional sections
...	Type of next section (32 bits)
...	Length of next section (32 bits)
Next section data	...