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77 lines
2.2 KiB
C
77 lines
2.2 KiB
C
/*
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* Copyright (C) 2013 Andrea Mazzoleni
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*
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* This program is free software: you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation, either version 2 of the License, or
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* (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful,
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* but WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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* GNU General Public License for more details.
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*/
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#ifndef __RAID_MEMORY_H
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#define __RAID_MEMORY_H
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/**
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* Memory alignment provided by raid_malloc_align().
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*
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* It should guarantee good cache performance everywhere.
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*/
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#define RAID_MALLOC_ALIGN 256
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/**
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* Memory displacement to avoid cache collisions on contiguous blocks,
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* ued by raid_malloc_vector().
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*
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* When allocating a sequence of blocks with a size of power of 2,
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* there is the risk that the start of each block is mapped into the same
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* cache line, resulting in cache collisions if you access all the blocks
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* in parallel, from the start to the end.
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*
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* The selected value was choosen empirically with some speed tests
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* with 8/12/16/20/24 data buffers and 3 parity buffers
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* for RAID-5/6/TP computation.
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*
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* With displacement (8 buffers, icore5, 32 bit):
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*
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* PAR1 sse2x4 21936 [MB/s]
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* PAR2 sse2x2 11902 [MB/s]
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* PARz sse2x1 5838 [MB/s]
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*
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* Without displacement:
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*
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* PAR1 sse2x4 15368 [MB/s]
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* PAR2 sse2x2 6814 [MB/s]
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* PARz sse2x1 3033 [MB/s]
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*/
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#define RAID_MALLOC_DISPLACEMENT (7*256)
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/**
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* Aligned malloc.
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*/
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void *raid_malloc_align(size_t size, void **freeptr);
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/**
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* Aligned vector allocation.
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* Returns a vector of "count" pointers, each one pointing to a block of the
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* specified "size".
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* The first "reverse" pointers are put in reverse memory offset order.
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*/
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void **raid_malloc_vector(size_t reverse, size_t count, size_t size, void **freeptr);
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/**
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* Tests the memory vector for RAM problems.
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* If a problem is found, it crashes.
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*/
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int raid_mtest_vector(void **vv, size_t count, size_t size);
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/**
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* Fills the memory vector with random data.
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*/
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void raid_mrand_vector(void **vv, size_t count, size_t size);
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#endif
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