Custom disk cache size appears to affect write cache only

[icelava]

When i manually set the cache size to say 128MB, i see on the Write Statistics cache expand to 128MB, while the Read Statistics cache remain filled at 18.1MB. What is the behaviour to increase the Read cache?

[thelittlefire]

... Cache is combined between R + W

You need to upload enough for the read cache to be useful. What's your set upload limit?

[icelava]

72KB/sec

It still appears 25-50% of uploads come from disk.

[Harold]

Well I'm not an µT dev (so take this with a grain of salt) but..

If it doesn't affect your read cache, your read cache is already max-size, as determined by the time that an unused piece will spend in the cache until it times out and your upload speed and even the number of peers: if there are few, they will ask for pieces that are in the cache less often than if there are many - the extreme case (1 peer) easily proves that (it should only request a piece that is already in the cache if it previously failed the hash check)

Peers tend to actively choose pieces that are rare (and therefore, have more chance of Not being in your cache, since pieces in your cache have already been downloaded by someone - making them less rare). I'm not sure how much this effect contributes to the miss-rate though..

[GTHK]

Read cache wont increase if you're using reduce memory usage when not needed, and possibly turn off read caching is upload speed is slow.

[icelava]

[Reduce memory usage when the cache is not needed] is on.

[Turn off read caching if the upload speed is slow] is off.

My question was why when i specified a custom cache size, it immediately went all to the Write cache (128MB vs 18.1MB Read cache), when i was uploading more than downloading.

[GTHK]

Dunno, that's just how it works. If you uncheck reduce mem then it'll use whatever you enter for both.