centos man page for set_dma_reserve

SET_DMA_RESERVE(9)					    Memory Management in Linux						SET_DMA_RESERVE(9)

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 present_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
Kernel Hackers Manual 3.10					     June 2014							SET_DMA_RESERVE(9)