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Unstable cpu/disk/dl-speed load


teglicha
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Hi.

After I upgraded my internet connection I decided to try few torrent clients.

My new internet connection is 1Gbps fiber with media converter -> router (RB951G-2HnD) -> LAN_cable -> desktop. OS is Windows 7 x64, no antivirus or firewall software, only the built-in Windows Firewall is active and everything is set up correctly, including port forwarding of the statically used port, and UPnP active on the router.

Bitcomet is latest 1.42 stable. Disk cache is the default 1024MB max. Disk is WD Black 1TB, but that doesn't matter, the same problem is with other disks).

What I encounter is choppy CPU/disk load when downloading 10-15GB worth of torrent tasks (2, 3, 4, or 10 tasks, doesn't matter).

I wait for the tasks to allocate etc., but looking at Task Manager and HDD led, I see frequent periods of about 3-4 seconds where the CPU is idle (2-3%) and at the same time the HDD is not active. This means not writing pieces and not downloading. During these periods the download rate within BC shows as slowing down progressively to below 15MB/s.

The peak download rate I get from BC is about 40 to 45MB/s max but rarely.

Comparatively I run uTorrent 2.2.1 (one after the other of course, 3-4 times in succession) with the same torrent tasks and it peaks at about 55-60MB/s with same 1024MB cache, disabled windows caching, AND more importantly - no drops in cpu or disk load all the way to the end.

Where should I seek to change some setting to make BC act adequately and have fluent cpu/disk loads across the lifetime of downloading the torrents with no such drops to idle for couple of seconds (or more)?

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By this you mean to rule out what? I could but for now I will save myself the pain to change few configurations for that.

Speedtest itself peaks at about 700 mbit/s (through the router) steadily country-wide, and about 600 mbit Europe-wide. The other torrent client unrolls slightly higher speeds and it doesn't drop disk or CPU load and its graph is fluent over time. These drops in load for CPU/disk (at the same time) are the issue at hand.

I think Bitcomet has some difficulty with higher speeds, maybe some advanced setting could affect this, I just don't know why is this happening.

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Can you try an SSD for a test? Just a little? Just to be sure. Or split tasks between two HDDs.

Or play with settings in Advanced options (mostly network.) Also try to set system.enable_disk_boost_service to false. Donno why, but I did this long time ago.

I have only 200 mbit/s and v 1.41.

Edited by torromania (see edit history)
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Hi. Thanks for taking the time.

I don't have an SSD in my main system. It is a 24/7 desktop with relatively constant number of running programs. I have 5 HDDs so I test different combinations.

The boost_service option was turned off the moment I installed BC. I read it had something to do with readyboost or something like that (external usb/flash devices..).

It's just every about 2 seconds the CPU goes down to 1-2% load, at the same time the HDDs LED is not lit (no disk activity), and during those 2-3 sec periods BC shows fast gradual drop in speed to below 15MB/s. When it starts again, it tops to about 40MB/s for the small timespan it actually downloads something and loads the CPU to 50-60%. The CPU graph is like a very sharp saw between 3% and 70% every 2-3 seconds. Again, during the low CPU, the disks are also "dead quiet".

It's weird.

The other torrent client doesn't exhibit anything like that, it steadily sustains above 50MB/s all the way to the end. I test with one 4-5GB torrent (2 files), I test with 5+ torrents simultaneously, with the same torrents (and number of) in both applications one after the other, and I conduct this test several times a day at different moments in day.

Edited by teglicha (see edit history)
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I'm sorry, I did many other tests and nothing helped. Either BC or this concrete version has sometthing wrong. I couldn't get more than 40MB/s without drops to idle every 2-3 sec. 2-3 sec idle -> 2-3 sec resources high and downloading -> 2-3 sec idle -> 2-3 sec resources high..... etc. endless cycle.

A friend having the same internet connection and ISP, is also suffering the same, he couldn't get above 45MB/s by Bc.

I wanted to ditch the other client but for now I just can't do it.

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The issue you describe is usually a hardware issue having to do with the internet connection being unable to handle the number of connections, rather than the bandwidth. If it was just speed, it would most likely be harddrive overload, and you'd see the same results across different clients, so I suspect bitcomet is more aggressively opening connections which can cause weak routers to overload and reboot. Member "torromania" seemed to be pointing to this likely issue when he suggested removing the router, however it is possible the problem is on the ISP side and although they do seem to offer some amazing speeds, many do add other types of throttling by using things like packet sniffing technologies to detect p2p downloads, or simply restricting the number of connections. If you are able to bypass your router that would be the fastest way to tell if it's your router that is cutting out, which has been a common problem, and with default settings bitcomet will attempt to open as many connections as your bandwidth can support and we've also included tools to limit the number of connections and the speed they open so that it can be detuned to a level that will work with a users existing equipment, but if you know for sure that your router is resetting and causing this problem, then the first course of action should be seeking a solution from the router manufacturer which is usually addressed with a firmware update. If that avenue doesn't provide any help then your options would be to either replace the device, or tune bitcomet to run within it's limitations. Some of these settings that could help are the Network max connections, network max connecting connections, network max udp packet per second, network max udp packet per second, network start connect interval, and the max connection per task, all of which are in the advanced options section and each is designed to limit a specific behavior and it will require a lot of trial and error to find the optimal settings. If you want to go this route I'd suggest using restrictive settings as a test and if it stops the problem, then you would need to determine what settings you can handle. Usually the default settings are "0" or unlimited, and I think I would try setting each to about 50 and if the problem ends, then see how high you can get each setting.

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Thanks for the long answer.

Now I tested again, this time with these settings (non-visible settings are defaults). Screenshot.

As you can see, there is just a single torrent task, with few peers (50-100). It behaves all the same, with the low/high resource cycle. I forgot to modify max_connections_per_task but I think it doesn't matter as we talk about one torrent only and the router's interface (Mikrotik -> Firewall - Connections) showed only about 180 connections in total of all kinds.

Just for comparison again - with the other torrent client, I set max connections to 5000, 500 per torrent etc, and the router's interface shows about 2500 connections (with 3-4 torrents or more), and there is no problem - it downloads without any drops in CPU and Disk IO, stable fluent graph, also HDD LED and Task Manager indications confirm that. I think the ISP is not restricting connections number, or if so, it would be very relaxed restriction.

But.... to be 100% sure, tomorrow I'll try without the router.

I just cannot imagine what's happening. I guess it's some combination of settings/version and my concrete internet connection. If BC could work without dropouts like this I guess it could reach very high speeds, higher than the other client. It's just when it reaches about 40-45MB/s and CPU_and_HDD drop to idle for 2-3 seconds at the same time, and the speed goes down and it has no "chance" to go higher than those 40-45MB as a result.

My friend is aso experiencing this limit but I will have to ask him to monitor closely CPU and disk IO to see if BC has the same cycling behavior for him, because he had not been doing it so far.

I'll return and test BC from time to time as I find new information about the possible problem.

Edited by teglicha (see edit history)
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Just tested without the router. The only difference is what was anticipated - the link speed is 940Mbps from speedtest, and the router limited it to about 700Mbps.

Bitcomet behaves the same way as with the router. Constant 3-second periods where the cpu and disk are idle-ing simultaneously. With just one/the_same torrent with no more than about 100 seeders.

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I can't edit my posts, so to be more precise I'll post a new one.

It appears that it was not the router that limits the max link speed but the primary network adapter which is in a WIndows MAC Bridge Miniport configuration (because of a VPN).

All my router-less experiments were using the second (also mainboard built-in) NIC which is not in a Bridge configuration. Now with the router in place, but using the second NIC, I can achieve the same 940Mbps with speedtest. Bitcomet seems to be absolutely unaffected by any configuration, with or without router, 1st or second NIC. It's like it has some software limit to about 45MB/s and once reached, it throttles for 2-3 seconds.

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I've never experienced any of the symptoms you report, but you might want to try 1.41 since there are other unrelated issues with 1.42. You can get all versions from the link in my signature, and you can try the .zip versions if you want to test one without installing.

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Thanks. I've got the ZIP 1.41. Can I test it side by side with 1.43 being already installed (but not running of course)? I mean I do not wish the zipped 1.41 to mess with my current settings in any way. Is the ZIP totally portable in this sense?

About the symptoms, I tested with 100 mbit connection, there are no such symptoms. They arise with the gigabit connection once it reach 45MB/s.

Edited by teglicha (see edit history)
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The ZIPped 1.41 picked up all the settings from the installed 1.42, so it doesn't seem too portable.

Anyway, 1.41 proved much worse. It's cycling the same way but the "idle" (CPU AND disk IO) part is much longer - about 5 seconds. Five seconds total PC idle, then 2-3 seconds of downloading and activity. Then 5 seconds of nothing, then ... etc. And the max seen speed here was below 40MB/s.

Again, the other client (uT) has no such behavior and it reaches stable 60+MB/s (and CPU and disk IO) to the very end of the download of torrents.

As 1.42 is a bit better than 1.41, I still think some option might be the culprit.

P.S. Now I see a new version 1.43 from few days ago. I will test it.

Edited by teglicha (see edit history)
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No change with 1.43. It's even worse. 2 sec downloading, 5 to 6 sec. absolute PC idle and doing nothing.

I give up now. Some day if I find the cuprit for this problem (if it's anything beyond Bitcomet at all), I'll post.

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All of your disks are connected to the motherboard SATA-controller?

The last thing - do like this:

bc_cache_size2234.png

bc_advance_sett2234.png

and check free RAM in the Task Manager. I doubt that it can help, but you can try.

Also you can run Prime 95 (blend test) at least for a few hours. This is what I would do in this case.

Edited by torromania (see edit history)
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