---
name: "set_dma_reserve"
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/set_dma_reserve"
---

# set\_dma\_reserve(9)

set the specified number of pages reserved in the first zone

## NAME

set\_dma\_reserve - set the specified number of pages reserved in the first zone

## SYNOPSIS

**void set\_dma\_reserve(unsigned long** *new\_dma\_reserve***);**

## ARGUMENTS

*new\_dma\_reserve*

The number of pages to mark reserved

## DESCRIPTION

The per-cpu batchsize and zone watermarks are determined by managed\_pages. In the DMA zone, a significant percentage may be consumed by kernel image and other unfreeable allocations which can skew the watermarks badly. This function may optionally be used to account for unfreeable pages in the first zone (e.g., ZONE\_DMA). The effect will be lower watermarks and smaller per-cpu batchsize.

## COPYRIGHT