Enum PerformanceWarning 

#[repr(u8)]
pub enum PerformanceWarning {
    OutstandingDiskBufferLimitReached = 0,
    OutstandingRequestLimitReached = 1,
    UploadLimitTooLow = 2,
    DownloadLimitTooLow = 3,
    SendBufferWatermarkTooLow = 4,
    TooManyOptimisticUnchokeSlots = 5,
    TooHighDiskQueueLimit = 6,
    AioLimitReached = 7,
    BittyrantWithNoUplimit = 8,
    TooFewOutgoingPorts = 9,
    TooFewFileDescriptors = 10,
}

Variants

OutstandingDiskBufferLimitReached = 0

This warning means that the number of bytes queued to be written to disk exceeds the max disk byte queue setting (settings_pack::max_queued_disk_bytes). This might restrict the download rate, by not queuing up enough write jobs to the disk I/O thread. When this alert is posted, peer connections are temporarily stopped from downloading, until the queued disk bytes have fallen below the limit again. Unless your max_queued_disk_bytes setting is already high, you might want to increase it to get better performance.

OutstandingRequestLimitReached = 1

This is posted when libtorrent would like to send more requests to a peer, but it’s limited by settings_pack::max_out_request_queue. The queue length libtorrent is trying to achieve is determined by the download rate and the assumed round-trip-time (settings_pack::request_queue_time). The assumed round-trip-time is not limited to just the network RTT, but also the remote disk access time and message handling time. It defaults to 3 seconds. The target number of outstanding requests is set to fill the bandwidth-delay product (assumed RTT times download rate divided by number of bytes per request). When this alert is posted, there is a risk that the number of outstanding requests is too low and limits the download rate. You might want to increase the max_out_request_queue setting.

UploadLimitTooLow = 2

This warning is posted when the amount of TCP/IP overhead is greater than the upload rate limit. When this happens, the TCP/IP overhead is caused by a much faster download rate, triggering TCP ACK packets. These packets eat into the rate limit specified to libtorrent. When the overhead traffic is greater than the rate limit, libtorrent will not be able to send any actual payload, such as piece requests. This means the download rate will suffer, and new requests can be sent again. There will be an equilibrium where the download rate, on average, is about 20 times the upload rate limit. If you want to maximize the download rate, increase the upload rate limit above 5% of your download capacity.

DownloadLimitTooLow = 3

This is the same warning as upload_limit_too_low but referring to the download limit instead of upload. This suggests that your download rate limit is much lower than your upload capacity. Your upload rate will suffer. To maximize upload rate, make sure your download rate limit is above 5% of your upload capacity.

SendBufferWatermarkTooLow = 4

We’re stalled on the disk. We want to write to the socket, and we can write but our send buffer is empty, waiting to be refilled from the disk. This either means the disk is slower than the network connection or that our send buffer watermark is too small, because we can send it all before the disk gets back to us. The number of bytes that we keep outstanding, requested from the disk, is calculated as follows:

.. code:: C++

min(512, max(upload_rate * send_buffer_watermark_factor / 100, send_buffer_watermark))

If you receive this alert, you might want to either increase your send_buffer_watermark or send_buffer_watermark_factor.

TooManyOptimisticUnchokeSlots = 5

If the half (or more) of all upload slots are set as optimistic unchoke slots, this warning is issued. You probably want more regular (rate based) unchoke slots.

TooHighDiskQueueLimit = 6

If the disk write queue ever grows larger than half of the cache size, this warning is posted. The disk write queue eats into the total disk cache and leaves very little left for the actual cache. This causes the disk cache to oscillate in evicting large portions of the cache before allowing peers to download any more, onto the disk write queue. Either lower max_queued_disk_bytes or increase cache_size.

AioLimitReached = 7

BittyrantWithNoUplimit = 8

👎Deprecated

TooFewOutgoingPorts = 9

This is generated if outgoing peer connections are failing because of address in use errors, indicating that settings_pack::outgoing_ports is set and is too small of a range. Consider not using the outgoing_ports setting at all, or widen the range to include more ports.

TooFewFileDescriptors = 10