Author Topic: qBT compiled with 3GB  (Read 975 times)

Henry63

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qBT compiled with 3GB
« on: April 26, 2015, 05:35:52 pm »
Since there is no 64bit version, may there be a version compiled with 3GB support, so virtual memory is increased by 50%? Right now, with a 1200MB cache, I am seeing about 1.8GB of virtual memory in use, so I dare not increase the cache any more, but if 3GB was compiled in, then I could add almost another 1GB.

On a side note, I see under statistics "read cache hits". I assume this is a hit rate and not the total number of hits, so 87 means 87% of reads hit the cache? The reason I ask is because I'm uploading about 3MB/s, but reading about 10MB/s from the HD. That brings up two questions. Even without the caching layer, why is my HD reading 3x more than I'm uploading? I can understand it won't match 1:1, but my intuition thinks it should be close, like less than 2x. Assuming 87 actually means 87% hit rate, shouldn't HD IO be less than upload rate if most of the data is being served from cache?

If the 87 doesn't actually mean an 87% hit rate, then what does it mean and is there a better algorithm to increase cache hits? I can understand that a small cache relative to the total data is impossible to make decent if the reads are effectively random over the entire data set, but most of my current uploading is being done by a smaller 5GB and the 1.2GB cache should be doing something. But yeah, 10MB/s read from HD and 3MB/s upload.


ciaobaby

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Re: qBT compiled with 3GB
« Reply #1 on: April 26, 2015, 07:23:53 pm »
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Since there is no 64bit version,

http://qbforums.shiki.hu/index.php/topic,1645.0.html
Smarter than the av-er-age bear, Boo Boo.

http://qbforums.shiki.hu/index.php/topic,3084.0.html

Switeck

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Re: qBT compiled with 3GB
« Reply #2 on: April 26, 2015, 09:46:01 pm »
"Right now, with a 1200MB cache, I am seeing about 1.8GB of virtual memory in use, so I dare not increase the cache any more"

The current cache in qBT (or rather libtorrent) is pretty buggy to be using so much memory for cache, and hopefully that will be improved without resorting to 64bit or using >2 GB virtual memory.
If virtual memory gets too low, qBT's cache may be swapped out to the pagefile which is likely on a hard drive...defeating the point of having a cache when that happens.
So it's very important for qBT's cache to become smaller and more efficient than it currently is...at least while downloading and/or uploading at >2 MegaBYTES/sec.

ciaobaby

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Re: qBT compiled with 3GB
« Reply #3 on: April 26, 2015, 10:40:09 pm »
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So it's very important for qBT's cache to become smaller and more efficient than it currently is

So reduce, it especially on Windows.

To see how much cache you ACTUALLY need, set cache control to auto and monitor the cache size every few hours over for 7 to 10 days using Tools -> Stats, keep a spreadsheet of the data so you can calculate the median.
Smarter than the av-er-age bear, Boo Boo.

http://qbforums.shiki.hu/index.php/topic,3084.0.html