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cache_calc_blocks; tidy up the calculation of nr blocks

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root 2014-06-16 13:42:13 +01:00
parent cb6edde141
commit ebb49db5d3
1 changed files with 20 additions and 17 deletions
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37
caching/cache_metadata_size.cc
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@ -93,39 +93,42 @@ namespace {
return CONTINUE;
}
void expand_flags(flags &fs) {
if (!fs.device_size && !fs.nr_blocks)
throw runtime_error("Please specify either --device-size and --block-size, or --nr-blocks.");
uint64_t get_nr_blocks(flags &fs) {
if (fs.device_size) {
if (!fs.block_size)
throw runtime_error("If you specify --device-size you must also give --block-size.");
if (fs.device_size && !fs.block_size)
throw runtime_error("If you specify --device-size you must also give --block-size.");
if (fs.block_size && !fs.device_size)
throw runtime_error("If you specify --block-size you must also give --device-size.");
if (fs.device_size && fs.block_size) {
uint64_t nr_blocks = *fs.device_size / *fs.block_size;
if (fs.nr_blocks) {
if (nr_blocks != *fs.nr_blocks)
throw runtime_error(
"Contradictory arguments given, --nr-blocks doesn't match the --device-size and --block-size.");
} else
fs.nr_blocks = nr_blocks;
}
return nr_blocks;
}
if (fs.block_size && !fs.device_size)
throw runtime_error("If you specify --block-size you must also give --device-size.");
if (fs.nr_blocks)
return *fs.nr_blocks;
throw runtime_error("Please specify either --device-size and --block-size, or --nr-blocks.");
}
uint64_t meg(uint64_t n) {
return n * 2048;
}
uint64_t calc_size(flags const &fs) {
uint64_t calc_size(uint64_t nr_blocks, uint32_t max_hint_width) {
uint64_t const SECTOR_SIZE = 512;
uint64_t const TRANSACTION_OVERHEAD = meg(4);
uint64_t const BYTES_PER_BLOCK = 16;
uint64_t const HINT_OVERHEAD_PER_BLOCK = 8;
uint64_t mapping_size = (*fs.nr_blocks * BYTES_PER_BLOCK) / SECTOR_SIZE;
uint64_t hint_size = (*fs.nr_blocks * (fs.max_hint_width + HINT_OVERHEAD_PER_BLOCK)) / SECTOR_SIZE;
uint64_t mapping_size = (nr_blocks * BYTES_PER_BLOCK) / SECTOR_SIZE;
uint64_t hint_size = (nr_blocks * (max_hint_width + HINT_OVERHEAD_PER_BLOCK)) / SECTOR_SIZE;
return TRANSACTION_OVERHEAD + mapping_size + hint_size;
}
}
@ -143,8 +146,8 @@ int main(int argc, char **argv)
break;
}
expand_flags(fs);
cout << calc_size(fs) << " sectors" << endl;
uint64_t nr_blocks = get_nr_blocks(fs);
cout << calc_size(nr_blocks, fs.max_hint_width) << " sectors" << endl;
} catch (std::exception const &e) {
cerr << e.what();