vfs_readv

NAME¶

vfs_readv - track vectored reads from the virtual filesystem

DESCRIPTION¶

This event captures read operations from files using the vectored I/O interface (readv). It is triggered by the VFS (Virtual File System) layer implementation of readv, preadv, and preadv2 system calls after file descriptor resolution.

The event provides information about the file being read, including its path and location in the filesystem, as well as details about the read operation such as the number of buffers and read position.

EVENT SETS¶

none

DATA FIELDS¶

pathname (string) : The path of the file being read

dev (uint32) : The device ID where the file resides

inode (uint64) : The inode number of the file on the device

vlen (uint64) : The number of buffers in the I/O vector for this read operation

pos (int64) : The file offset where the read operation starts

DEPENDENCIES¶

vfs_readv: Kernel probe on the VFS readv implementation
vfs_readv_ret: Return probe for operation completion

USE CASES¶

I/O pattern analysis: Understand how applications use vectored I/O
Performance optimization: Identify inefficient read patterns
Security monitoring: Track sensitive file access
Debugging: Diagnose file read issues

IMPLEMENTATION NOTES¶

Triggered by the VFS layer, independent of specific filesystems
Captures vectored reads from readv, preadv, and preadv2 syscalls
Does not capture other read methods like read, memory mapping, etc.
Uses both entry and return probes for complete operation tracking

FILE ACCESS METHODS¶

Common file read methods in Linux:

read: Single buffer read
readv: Vectored I/O (this event)
pread/preadv: Positioned reads
mmap: Memory-mapped I/O
sendfile: Direct file-to-file transfer

vfs_read: Single buffer read operations
vfs_writev: Vectored write operations
readv: System call for vectored reads
preadv: Positioned vectored reads