---
name: "blk_lld_busy"
section: "9"
platform: "linux"
package: "linux-manual-4.9"
version: "4.9.228-1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/blk_lld_busy"
---

# blk\_lld\_busy(9)

Check if underlying low-level drivers of a device are busy

## NAME

blk\_lld\_busy - Check if underlying low-level drivers of a device are busy

## SYNOPSIS

**int blk\_lld\_busy(struct request\_queue \*** *q***);**

## ARGUMENTS

*q*

the queue of the device being checked

## DESCRIPTION

Check if underlying low-level drivers of a device are busy. If the drivers want to export their busy state, they must set own exporting function using **blk\_queue\_lld\_busy** first.

Basically, this function is used only by request stacking drivers to stop dispatching requests to underlying devices when underlying devices are busy. This behavior helps more I/O merging on the queue of the request stacking driver and prevents I/O throughput regression on burst I/O load.

## RETURN

0 - Not busy (The request stacking driver should dispatch request) 1 - Busy (The request stacking driver should stop dispatching request)

## COPYRIGHT