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[Disk Cache] Unable to attain high download speeds


Lord Alderaan

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µtorrent's disk cache doesn't seem to be able to handle high speeds (more then 2MB/s to 5MB/s) correctly. The cache will fill with downloaded data but won't write out accordingly until it is full. It will then cause a disc overload or slow the torrent down to between 2MB/s and 5MB/s.

In some cases stopping and resuming a torrent after a while (before the cache has been totally filled) seems to solve the problem. After doing this the torrent in question and torrents started/loaded after that are able to reach speeds of up to 22MB/s (the ISP/NIC transfer speed and HD write speed start to become the likely bottlenecks here).

Reported this bug here not from personal experience but based on observations made by a couple of users of this forum. See related topic:

http://forum.utorrent.com/viewtopic.php?id=21356 For detailed descriptions of the individual cases.

[edit]

I meant the µtorrent disk cache, not the hard drives own cache.

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True,

But do you mean HD cache?

My experience is that the problem is writing from the assigned cache in uTorrent (memory) to the disk that is very slow.

And it also looks like it matter where which torrent / tracker you are using which is reported.

Some trackers / torrents are writing faster from cashe to disk.

Can it be different sizes of the blocks in different torrents that matters?

Edit:

Lord Alderan,

I am not sure that you (at least I) mean disk cache.

uTorrent disk cache is the located in the physical memory, as long as you are not using the Virtual Memory (VM) which is on the HD.

As above uT is slow to write from MEMORY to hard disk.

In most cases uT only starts writing from memory to disk once the assigned disk cache (memory) is full and "disk overload" appears.

Can it be uT trying to write to disk in a "smart"/consecutive way, and therefore not starting to write as soon as Bytes are downloaded to memory and then writing at full speed?

Found the way to show images, so I am updating with the graph of initial fast DL to cache and then the drastic decrease of DL speed to the speed of the disk write..

writingtodisk22lw5.th.jpg

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