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attempt to mitigate read cache thrashing

This commit is contained in:
Arvid Norberg 2009-05-24 16:49:01 +00:00
parent 29d56f9a8b
commit 2f627a4b00
2 changed files with 15 additions and 8 deletions
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2
include/libtorrent/disk_io_thread.hpp
View File

@ -311,7 +311,7 @@ namespace libtorrent
int clear_oldest_read_piece(int num_blocks, cache_t::iterator ignore
, mutex_t::scoped_lock& l);
int read_into_piece(cached_piece_entry& p, int start_block
, int options, mutex_t::scoped_lock& l);
, int options, int num_blocks, mutex_t::scoped_lock& l);
int cache_read_block(disk_io_job const& j, mutex_t::scoped_lock& l);
int cache_read_piece(disk_io_job const& j, mutex_t::scoped_lock& l);
int free_piece(cached_piece_entry& p, mutex_t::scoped_lock& l);

21
src/disk_io_thread.cpp
View File

@ -760,7 +760,7 @@ namespace libtorrent
// fills a piece with data from disk, returns the total number of bytes
// read or -1 if there was an error
int disk_io_thread::read_into_piece(cached_piece_entry& p, int start_block
, int options, mutex_t::scoped_lock& l)
, int options, int num_blocks, mutex_t::scoped_lock& l)
{
int piece_size = p.storage->info()->piece_size(p.piece);
int blocks_in_piece = (piece_size + m_block_size - 1) / m_block_size;
@ -784,8 +784,7 @@ namespace libtorrent
++m_cache_stats.read_cache_size;
++end_block;
++num_read;
#error the length should be min(read_cache_line_size, (cache_size - in_use())/2)
if (num_read >= m_settings.read_cache_line_size) break;
if (num_read >= num_blocks) break;
}
if (end_block == start_block) return -2;
@ -867,6 +866,8 @@ namespace libtorrent
// returns -1 on read error, -2 on out of memory error or the number of bytes read
// this function ignores the cache size limit, it will read the entire
// piece regardless of the offset in j
// this is used for seed-mode, where we need to read the entire piece to calculate
// the hash
int disk_io_thread::cache_read_piece(disk_io_job const& j, mutex_t::scoped_lock& l)
{
INVARIANT_CHECK;
@ -885,7 +886,7 @@ namespace libtorrent
p.blocks.reset(new (std::nothrow) char*[blocks_in_piece]);
if (!p.blocks) return -1;
std::memset(&p.blocks[0], 0, blocks_in_piece * sizeof(char*));
int ret = read_into_piece(p, 0, ignore_cache_size, l);
int ret = read_into_piece(p, 0, ignore_cache_size, INT_MAX, l);
if (ret == -1)
free_piece(p, l);
@ -906,7 +907,10 @@ namespace libtorrent
int start_block = j.offset / m_block_size;
int blocks_to_read = (std::min)(blocks_in_piece - start_block, m_settings.read_cache_line_size);
int blocks_to_read = blocks_in_piece - start_block;
blocks_to_read = (std::min)(blocks_to_read, (std::max)((m_settings.cache_size
+ m_cache_stats.read_cache_size - in_use())/2, 3));
blocks_to_read = (std::min)(blocks_to_read, m_settings.read_cache_line_size);
if (in_use() + blocks_to_read > m_settings.cache_size)
if (flush_cache_blocks(l, in_use() + blocks_to_read - m_settings.cache_size
@ -921,7 +925,7 @@ namespace libtorrent
p.blocks.reset(new (std::nothrow) char*[blocks_in_piece]);
if (!p.blocks) return -1;
std::memset(&p.blocks[0], 0, blocks_in_piece * sizeof(char*));
int ret = read_into_piece(p, start_block, 0, l);
int ret = read_into_piece(p, start_block, 0, blocks_to_read, l);
if (ret == -1)
free_piece(p, l);
@ -1082,12 +1086,15 @@ namespace libtorrent
while (end_block < blocks_in_piece && p->blocks[end_block] == 0) ++end_block;
int blocks_to_read = end_block - block;
blocks_to_read = (std::min)(blocks_to_read, (std::max)((m_settings.cache_size
+ m_cache_stats.read_cache_size - in_use())/2, 3));
blocks_to_read = (std::min)(blocks_to_read, m_settings.read_cache_line_size);
if (in_use() + blocks_to_read > m_settings.cache_size)
if (flush_cache_blocks(l, in_use() + blocks_to_read - m_settings.cache_size
, p, dont_flush_write_blocks) == 0)
return -2;
int ret = read_into_piece(*p, block, 0, l);
int ret = read_into_piece(*p, block, 0, blocks_to_read, l);
hit = false;
if (ret < 0) return ret;
TORRENT_ASSERT(p->blocks[block]);