From: Mario Smarduch <Mario.Smarduch@huawei.com>
To: "linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: questions about free_area_init_core(), SPARSEMEM, DMA
Date: Wed, 24 Oct 2012 12:18:34 +0000 [thread overview]
Message-ID: <2DDB038789B01B4B80B0D3F1FF7CBDC20645F788@lhreml509-mbb.china.huawei.com> (raw)
In frea_area_init_core()
for each zone calculates
memmap_pages=PAGE_ALIGN(size * sizeof(struct page)) >> PAGE_SHIFT;
Which is total memory range zone spans and then it subtracts that value from
realsize (memory present in zone). I'm bit confused for SPARSEMEM case
where sections not occupied don't have memmap arrays (mem_section[] indexed)
allocated. Should not the calculation of memmap_pages above take that into
consideration?
Also related to same function I've notice 'dma_reserve' is hardly defined
anywhere. The boards I've looked at (ARM PBX, PXA) have their kernel
text, data, bss allocated in DMA zone, any reasons why 'dma_reserve' is
not defined to correctly determine zone watermarks and other things later
on?
- Mario
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reply other threads:[~2012-10-24 12:18 UTC|newest]
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