Difference between revisions of "VPP/cpel"
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Revision as of 15:40, 12 February 2016
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 |
