Re: Tor speed

[slush <slush@xxxxxxxx>]

I know that latency is the real reason of user experience. But my speed tests were averages for longer time and many requests. When I have faster connection, but it feels much slower.

Tor:
request > ..... noooothiiiing for minute > ........ page is loading in ten seconds with all images (and bandwidth meter shows me speed above 140 kB/s).

JAP:
request > .... few second for first response > slower, but continuous page loading for longer than minute > done (and maximum speed wasnt better than few kB/s)

Second behaviour is much better, because you feel the responsivity and in some cases, you can read page until it is fully loaded.

Im asking, why is Tor different in this. Is there any reason in tor design or it is simply not too optimized? Because in total, there IS enough bandwidth on nodes (overal speed is sufficient).

Reason 1, latency)
I understand, that JAP (with most servers in germany) will be more responsive than Tor, which have nodes around whole world and one request is pending across continents. But: There are 3 nodes, me and target server (4 connections in line total). We can expect, that every node is on different continent and on bad line (~ 400 ms latency). My latencies (Im 3ms to Czech internet bone) to USA are around 140ms. So at total:

me -- 400 + 140 + 400 -- node1 --- 400 + 140 + 400 --- node2 --- 940 --- node3 --- 940 --- target

==== 3760 ms for one-way, it is ~7,5 second to response in the WORST case!! Dont tell me, that 940 ms is typical latency between nodes...

Reason 2, node overall throughput)
Slow responsibility can be done by slow nodes connection. But overall speed is not a problem (not for me), because there IS enough connectivity, but probably badly spread in time. Im running exit node (https://torstatus.blutmagie.de/router_detail.php?FP=9a8eb14286dea095815b702f6d6f7d1d6d051da7) and I can see, that my bandwidth is not used in the best way. Sometimes node is idle and sometimes it hit the speed limits. In idle time is probably everything ok - node is working on every request without own speed limitation. But what in the case of short-time overloading? My tip is, that in this case, node is working for somebody faster than for else. I think so, because it can be the reason, why I often have ZERO throughput thru Tor for tens seconds. My guess is that some nodes simply dont give me a slot for my data, because somebody else is transfering something big, what "kill" the bandwidth for a moment. And because there are three nodes in the line, it is the big probability I "hit" this problem on more nodes - and I will finally very slow responsibility.

Hight throughput on the end of request (as I wrote on begin) is also an evidence - when I use so much bandwidth for a few seconds, somebody else must wait. Because there are tens of users on one node, it support my idea.

Is there anybody, who knows, if it is possible?

Thanks,
Marek

On Fri, Feb 13, 2009 at 4:31 AM, coderman <coderman@xxxxxxxxx> wrote:

latency is also an important component to measure.  especially when
content, like html pages, contains many nested elements or links which
require additional connections to other sites.  the latencies are
additive and some elements of an HTML document are not rendered until
a sufficient number of bytes / linked entities are loaded.

best regards,