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try to optimize disk write performance by raising the low watermark (for disk thread queue) to start reading from sockets and also post the start-reading event earlier. Also implement fair round-robin of which peers get to start downloading on this event

This commit is contained in:
Arvid Norberg 2011-03-27 20:35:38 +00:00
parent 346a6fb175
commit f6a42863e3
2 changed files with 26 additions and 39 deletions
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16
src/disk_io_thread.cpp
View File

@ -1583,10 +1583,6 @@ namespace libtorrent
for (;;)
{
// used to indicate whether or not we should post the
// 'restart download' event or not.
bool post = false;
#ifdef TORRENT_DISK_STATS
m_log << log_time() << " idle" << std::endl;
#endif
@ -1675,10 +1671,10 @@ namespace libtorrent
if (m_exceeded_write_queue)
{
int low_watermark = m_settings.max_queued_disk_bytes_low_watermark == 0
? m_settings.max_queued_disk_bytes / 2
? m_settings.max_queued_disk_bytes * 7 / 8
: m_settings.max_queued_disk_bytes_low_watermark;
if (low_watermark >= m_settings.max_queued_disk_bytes)
low_watermark = m_settings.max_queued_disk_bytes / 2;
low_watermark = m_settings.max_queued_disk_bytes * 7 / 8;
if (m_queue_buffer_size < low_watermark
|| m_settings.max_queued_disk_bytes == 0)
@ -1687,7 +1683,7 @@ namespace libtorrent
// we just dropped below the high watermark of number of bytes
// queued for writing to the disk. Notify the session so that it
// can trigger all the connections waiting for this event
post = true;
if (m_queue_callback) m_ios.post(m_queue_callback);
}
}
}
@ -1797,12 +1793,6 @@ namespace libtorrent
disk_buffer_holder holder(*this
, operation_has_buffer(j) ? j.buffer : 0);
if (post && m_queue_callback)
{
TORRENT_ASSERT(m_exceeded_write_queue == false);
m_ios.post(m_queue_callback);
}
flush_expired_pieces();
int ret = 0;

49
src/session_impl.cpp
View File

@ -566,6 +566,7 @@ namespace aux {
#endif
m_next_lsd_torrent = m_torrents.begin();
m_next_connect_torrent = m_torrents.begin();
m_next_disk_peer = m_connections.begin();
if (!listen_interface) listen_interface = "0.0.0.0";
m_listen_interface = tcp::endpoint(address::from_string(listen_interface, ec), listen_port_range.first);
@ -2345,6 +2346,8 @@ namespace aux {
c->set_upload_limit(m_settings.default_peer_upload_rate);
if (m_settings.default_peer_download_rate)
c->set_download_limit(m_settings.default_peer_download_rate);
// update the next disk peer round-robin cursor
if (m_next_disk_peer == m_connections.end()) m_next_disk_peer = m_connections.begin();
}
}
@ -2410,7 +2413,10 @@ namespace aux {
boost::intrusive_ptr<peer_connection> sp((peer_connection*)p);
connection_map::iterator i = m_connections.find(sp);
// make sure the next disk peer round-robin cursor stays valid
if (m_next_disk_peer == i) ++m_next_disk_peer;
if (i != m_connections.end()) m_connections.erase(i);
if (m_next_disk_peer == m_connections.end()) m_next_disk_peer = m_connections.begin();
}
void session_impl::set_peer_id(peer_id const& id)
@ -2466,35 +2472,26 @@ namespace aux {
{
TORRENT_ASSERT(is_network_thread());
std::vector<peer_connection*> conns;
conns.reserve(m_connections.size() / 2);
for (connection_map::iterator i = m_connections.begin();
i != m_connections.end(); ++i)
// just to play it safe
if (m_next_disk_peer == m_connections.end()) m_next_disk_peer = m_connections.begin();
// never loop more times than there are connections
// keep in mind that connections may disconnect
// while we're looping, that's why this is a reliable
// way of limiting it
int limit = m_connections.size();
do
{
peer_connection* p = i->get();
--limit;
peer_connection* p = m_next_disk_peer->get();
++m_next_disk_peer;
if (m_next_disk_peer == m_connections.end()) m_next_disk_peer = m_connections.begin();
if (p->m_channel_state[peer_connection::download_channel]
!= peer_info::bw_disk) continue;
p->on_disk();
conns.push_back(p);
}
if (conns.empty()) return;
// pick a random peer to start with, to evenly distribute
// the disk bandwidth
std::vector<peer_connection*>::iterator peer = conns.begin() + (rand() % conns.size());
for (int i = 0; i < conns.size(); ++i)
{
// if we can't write to disk anymore, no need
// to keep iterating
if (!can_write_to_disk()) break;
// setup_receive() may disconnect the connection
// and clear it out from the m_connections list
(*peer)->on_disk();
++peer;
if (peer == conns.end()) peer = conns.begin();
}
} while (m_next_disk_peer != m_connections.end() && limit > 0 && can_write_to_disk());
}
// used to cache the current time
@ -2914,7 +2911,7 @@ namespace aux {
}
int low_watermark = m_settings.max_queued_disk_bytes_low_watermark == 0
? m_settings.max_queued_disk_bytes / 2
? m_settings.max_queued_disk_bytes * 7 / 8
: m_settings.max_queued_disk_bytes_low_watermark;
if (now - m_last_log_rotation > hours(1))