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author | Ingo Molnar <mingo@kernel.org> | 2017-01-28 12:45:40 +0100 |
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committer | Ingo Molnar <mingo@kernel.org> | 2017-01-28 14:42:28 +0100 |
commit | 4270fd8b4c27f08b9cfd7e2fc342d1a31217ba6b (patch) | |
tree | fc7bbcf62c144827785a8efdf2c9e488c984491e /arch/x86/mm | |
parent | 01259ef1e0901310aa4a87754ff07a1b2fe6a433 (diff) | |
download | linux-stable-4270fd8b4c27f08b9cfd7e2fc342d1a31217ba6b.tar.gz linux-stable-4270fd8b4c27f08b9cfd7e2fc342d1a31217ba6b.tar.bz2 linux-stable-4270fd8b4c27f08b9cfd7e2fc342d1a31217ba6b.zip |
x86/boot/e820: Move the memblock_find_dma_reserve() function and rename it to memblock_set_dma_reserve()
We introduced memblock_find_dma_reserve() in this commit:
6f2a75369e75 x86, memblock: Use memblock_memory_size()/memblock_free_memory_size() to get correct dma_reserve
But there's several problems with it:
- The changelog is full of typos and is incomprehensible in general, and
the comments in the code are not much better either.
- The function was inexplicably placed into e820.c, while it has very
little connection to the E820 table: when we call
memblock_find_dma_reserve() then memblock is already set up and we
are not using the E820 table anymore.
- The function is a wrapper around set_dma_reserve(), but changed the 'set'
name to 'find' - actively misleading about its primary purpose, which is
still to set the DMA-reserve value.
- The function is limited to 64-bit systems, but neither the changelog nor
the comments explain why. The change would appear to be relevant to
32-bit systems as well, as the ISA DMA zone is the first 16 MB of RAM.
So address some of these problems:
- Move it into arch/x86/mm/init.c, next to the other zone setup related
functions.
- Clean up the code flow and names of local variables a bit.
- Rename it to memblock_set_dma_reserve()
- Improve the comments.
No change in functionality. Enabling it for 32-bit systems is left
for a separate patch.
Cc: Alex Thorlton <athorlton@sgi.com>
Cc: Andy Lutomirski <luto@kernel.org>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Gerst <brgerst@gmail.com>
Cc: Dan Williams <dan.j.williams@intel.com>
Cc: Denys Vlasenko <dvlasenk@redhat.com>
Cc: H. Peter Anvin <hpa@zytor.com>
Cc: Huang, Ying <ying.huang@intel.com>
Cc: Josh Poimboeuf <jpoimboe@redhat.com>
Cc: Juergen Gross <jgross@suse.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Paul Jackson <pj@sgi.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Wei Yang <richard.weiyang@gmail.com>
Cc: Yinghai Lu <yinghai@kernel.org>
Cc: linux-kernel@vger.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch/x86/mm')
-rw-r--r-- | arch/x86/mm/init.c | 47 |
1 files changed, 47 insertions, 0 deletions
diff --git a/arch/x86/mm/init.c b/arch/x86/mm/init.c index b7b4ad569d13..922671d3af85 100644 --- a/arch/x86/mm/init.c +++ b/arch/x86/mm/init.c @@ -724,6 +724,53 @@ void __init free_initrd_mem(unsigned long start, unsigned long end) } #endif +/* + * Calculate the precise size of the DMA zone (first 16 MB of RAM), + * and pass it to the MM layer - to help it set zone watermarks more + * accurately. + * + * Done on 64-bit systems only for the time being, although 32-bit systems + * might benefit from this as well. + */ +void __init memblock_find_dma_reserve(void) +{ +#ifdef CONFIG_X86_64 + u64 nr_pages = 0, nr_free_pages = 0; + unsigned long start_pfn, end_pfn; + phys_addr_t start_addr, end_addr; + int i; + u64 u; + + /* + * Iterate over all memory ranges (free and reserved ones alike), + * to calculate the total number of pages in the first 16 MB of RAM: + */ + nr_pages = 0; + for_each_mem_pfn_range(i, MAX_NUMNODES, &start_pfn, &end_pfn, NULL) { + start_pfn = min(start_pfn, MAX_DMA_PFN); + end_pfn = min(end_pfn, MAX_DMA_PFN); + + nr_pages += end_pfn - start_pfn; + } + + /* + * Iterate over free memory ranges to calculate the number of free + * pages in the DMA zone, while not counting potential partial + * pages at the beginning or the end of the range: + */ + nr_free_pages = 0; + for_each_free_mem_range(u, NUMA_NO_NODE, MEMBLOCK_NONE, &start_addr, &end_addr, NULL) { + start_pfn = min_t(unsigned long, PFN_UP(start_addr), MAX_DMA_PFN); + end_pfn = min_t(unsigned long, PFN_DOWN(end_addr), MAX_DMA_PFN); + + if (start_pfn < end_pfn) + nr_free_pages += end_pfn - start_pfn; + } + + set_dma_reserve(nr_pages - nr_free_pages); +#endif +} + void __init zone_sizes_init(void) { unsigned long max_zone_pfns[MAX_NR_ZONES]; |