An user on the libtorrent mailing list had the following problem:<\/p>\n
I’m doing some testing for a libtorrent application that will use a small number of peers (often just 1 seed and 1 downloaded) and high bandwidth delay product links (in the hundreds of Mb\/s and 100ms+ round trip). I’m unable to get more than 20Mbps with a single peer on a 140ms RTT link (simulated delay with no packet loss). If I take the network simulator delay down to 0, I can get almost a full 1000Mbps on the same system. I’ve tried playing with everything that sounded relevant in session_settings, but nothing seems to make any improvement at all.<\/p>\n
Is this the best that can be expected out of uTP on a high latency link? Or is there some combination of parameters that would improve the single peer throughput? Alternatively, is there a way to get libtorrent to make multiple connections between the same 2 peers?<\/p><\/blockquote>\n
If you’re facing a similar situation here are some things you could adjust according to Arvid Norberg<\/a> lead engineer of the libtorrent project<\/a>.<\/p>\n
“Did you increase the socket buffer sizes on both ends?”<\/strong><\/p>\n
int recv_socket_buffer_size;\nint send_socket_buffer_size;\n<\/code><\/pre>\n“There’s also buffer sizes at the bittorrent level:”<\/strong><\/p>\n
int send_buffer_low_watermark;\nint send_buffer_watermark;\nint send_buffer_watermark_factor;\n<\/code><\/pre>\n“And there are buffers at the disk layer:”<\/strong><\/p>\n
int max_queued_disk_bytes;\nint max_queued_disk_bytes_low_watermark;\n<\/code><\/pre>\nIf the performance issue happens with uTP but not TCP though, it’s probably
\njust the first ones that matters.<\/p>\nAlso, the uTP implementation needs a system call for each packet sent and
\nreceived (i.e. it does not use sendmmsg()\/recvmmsg()) which also makes it
\nmore expensive than TCP, but that would primarily cause additional CPU
\nusage, and only slow-downs once a CPU core is pegged.<\/p>\n","protected":false},"excerpt":{"rendered":"An user on the libtorrent mailing list had the following problem: I’m doing some testing for a libtorrent application that will use a small number of peers (often just 1 seed and 1 downloaded) and high bandwidth delay product links (in the hundreds of Mb\/s and 100ms+ round trip). I’m unable to get more than […]<\/p>\n","protected":false},"author":1,"featured_media":3470,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_jetpack_newsletter_access":"","_jetpack_dont_email_post_to_subs":false,"_jetpack_newsletter_tier_id":0,"_jetpack_memberships_contains_paywalled_content":false,"_jetpack_feature_clip_id":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":true,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2},"jetpack_post_was_ever_published":false},"categories":[1475,15,30,60],"tags":[204,1476,1477,703,1478],"class_list":["post-3469","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-bittorrent","category-code","category-geeklife","category-p2p","tag-bittorrent","tag-jlibtorrent","tag-libtorrent","tag-networking","tag-performance"],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"https:\/\/i0.wp.com\/www.gubatron.com\/blog\/wp-content\/uploads\/2016\/01\/latency.jpg?fit=1000%2C667&ssl=1","jetpack_sharing_enabled":true,"jetpack_shortlink":"https:\/\/wp.me\/p5Unzf-TX","jetpack-related-posts":[{"id":994,"url":"https:\/\/www.gubatron.com\/blog\/new-frostwire-4172-for-windows-is-out\/","url_meta":{"origin":3469,"position":0},"title":"New FrostWire 4.17.2 for Windows is out","author":"gubatron","date":"November 23, 2008","format":false,"excerpt":"Download FrostWire 4.17.2 for Windows CHANGELOG: Version 4.17.2 (November 2008) Fixes a newly introduced bug in Windows which would make FrostWire(tm) take over the .bittorrent file association without asking the user. 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El dilema de este geek es ahora... espero un par de horas y\u2026","rel":"","context":"In "Geeklife"","block_context":{"text":"Geeklife","link":"https:\/\/www.gubatron.com\/blog\/category\/geeklife\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":490,"url":"https:\/\/www.gubatron.com\/blog\/descarga-50-wallpapers-de-scarlett-johansson-en-frostclickcom\/","url_meta":{"origin":3469,"position":4},"title":"Descarga 50 Wallpapers de Scarlett Johansson en FrostClick.com","author":"gubatron","date":"April 4, 2007","format":false,"excerpt":"Asi se ve mi escritorio Kubuntu hoy despues de ver 50 wallpapers de alta resolution (1920x1200) disponibles en FrostClick.com, alli encontraras un torrent que puedes utilizar con FrostWire o tu cliente de BitTorrent Favorito.","rel":"","context":"In "Geeklife"","block_context":{"text":"Geeklife","link":"https:\/\/www.gubatron.com\/blog\/category\/geeklife\/"},"img":{"alt_text":"","src":"","width":0,"height":0},"classes":[]},{"id":945,"url":"https:\/\/www.gubatron.com\/blog\/new-frostwire-4171-released\/","url_meta":{"origin":3469,"position":5},"title":"New FrostWire 4.17.1 Released","author":"gubatron","date":"November 8, 2008","format":false,"excerpt":"Source FOR IMMEDIATE RELEASE: Official FrostWire 4.17.1 Download link FrostWire.com -- The last of the 4.17.x FrostWire series is finally out. 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