How Fast Too Slow? A Study Of Quake Pings

Jonathan Lennox writes: "Grenville Armitage has published an analysis of ping times of clients connecting to his Quake III Arena server. His conclusion is that 150 milliseconds is the limit that people find tolerable, and says this may have interesting implications for Internet Quality of Service research."

Comments

Re:Implications for what?

[nyet]

PHB's would love you to think that the internet is used primarily for business email (upper management email tends to be MORE important btw. even if it is to schedule the wife's baby shower) and for people surfing corporate sites for *valuable* marketing information.

As if that requires any real bandwidth or requires low latency/packet loss/jitter.

99% of the Internet is porn and games. Porn doesn't require low latency, low jitter or low packet loss, and can be safely QoS'ed into the "available bandwith" slot along with Mr. CEO's VITALLY IMPORTANT email to his golfing pals.

The only thing left is games and VoIP.

The latter is strictly CBR.

This leaves GAMES.

Nobody wants to admit this. It is the Internet's dirty little secret that when a company complains to an ISP about its shitty latency and packet loss rates, it is NOT because Mr. PHB can't check his stock portfolio (after all, he can do this over a modem with 20%+ packet loss and a ping of 500 ms). It is because somebody in the IT staff just got fragged by an LPB.

Wrong conclusion!!!

[throx]

I don't follow how he got the measure of 150ms as what people prefer. What the data really shows is that most people who connected to his quake server had a ping time of under 150ms (which actually covers most of the US from the plots he drew).

Let's think about this a little more:

i) He's on a T1 and possibly advertises the fact.
ii) Serious MP Quake players will have a fast connection (DSL/Cable) and not a modem.
iii) Quake players will *choose* the lowest ping because it seems like a good idea - they won't reject a server over 150ms, just prefer one below it.

Looking at the results, the best he can say is that most people that play on his server are from the US, which for the most part keeps their ping under 150ms. You can't draw any assumptions about what people "prefer" from that data.

overstated conclusions

[Illserve]

Based on analysis of a QuakeIII server over two months in early 2001, first person shooter (FPS) game players strongly prefer servers that are within 150 milliseconds of the player's attachment point to the Internet. Or put another way, if you are planning on hosting a for-fee FPS server service, you should forget about trying to get customers who are more than 150 milliseconds away from your servers. Sections of the Internet more than 150 milliseconds away will provide a minimal source of regular players (and hence minimal revenue).

I fail to see how this indicates some kind of acceptable limit. A similar study done 2 years ago might have reached exactly the same kind of conclusion for 200 msec. Within a year, it might yield 100 msec.

All this tells us is that most players succeed at getting 150msec pings if they can. It doesn't tell us whether they find this number satisfying. If they were unable to play at 150, they might very well be happy playing at 200 or 250.

So this doesn't tell a potential service provider anything beyond the current status of the internet's average ping times. And such data will be useless in a year.

What would demonstrate his point would be players who didn't know what their ping was, and were able to switch between servers with known pings in a controlled situation (50/100/150/200... for example). One could then watch where the players end up, if you saw no difference between the 50 and 100 ping servers, you could *then* conclude that players were satisfied with 100 and saw no need to try to get to 50.

Gradients, not total colors

[UnknownSoldier]

> The human eye can only recognize a color depth of X, where X is less than current standard "true-color" depths. Yet we still have 32 bit color. Why?

Short anwer:
Where's the COLOR faq when you need it? :-)

Seriously,

Gamma ties into this, which I'll ignore, since it a different problem, but the short answer is: you want as many colors as possible when you need to interpolate between any given 2. e.g. a high gradient.

At 32 bit color, with 8 bits per channel (e.g. 3 channels = red, green, blue) that gives us 256 levels for primary gradients. (Less for non-primary colors.)

32 bit is still too low, though. Ideally we should have 16-bit per channel (i.e. 48 bit color) since our eye is more sensitive to greens, and 256 shades isn't quite enough.

So it's not about TOTAL colors, but about the NUMBER of color steps BETWEEN colors.

Blending, or "overlaying" transparent textures is another reason high bit depths matter. If you overlay 8 transparent objects in 16-bit color, you get [bad] artifacts. You can see this on the older Voodoo cards, when you had transparent smoke.

And finally, memory access if MUCH faster if memory is aligned on a power of 2. 24 is not a power of 2, while 32 is. Memory controllers are slower if they have to access memory on odd alignment. There was a paper few years ago paper showing you a "wierd" memory touching walk where instead of doing
for (int i = 0; i &lt 100000; i++ )
block[i] = c;
it would be faster to do
block[i+0] = c;
block[i+2] = c;
block[i+1] = c;
block[i+3] = c;

> will having our color depth set to 32bpp instead of 24 make a difference,

Aside from the major speed difference, visually no, because the last 8 bits in 32bit color are usually used for alpha (the level of opacity)

> So the question is, even though you can only see one third of those 210 frames per second, does that make your playing more enjoyable or better?
It's an expontential curve of decreasing returns.
i.e. double the frame rate from 10 to 20, is MUCH more noticable then the double jump from 30 to 60.

But there are a few reasons you want &gt 100 hz frame rates.
a) The more people that are on screen, the lower the frame-rate. You want a high frame rate so when the action gets "thick and heavy" your frame rate still is above 60.

b) I find a monitor with 100 hz to be rock solid and easy on the eyes. At lower frequence (like 60) Hz I get a head ache (probably because the way our body clock is tied to 60 hz)

> Similarly, does looking at a 48bpp image make you happier than looking at a 24bpp image,

You get less "Mach banding" with a higher bit depth.

Again, this is another example expontential curve of decreasing returns. 48 bpp is "very good". 24 bpp is "good enough"

Hope this helps.

Finally!

[zpengo]

The important thing is that now we have a number. In the past, insults were reserved for AOLers and the like, who were obviously HPBs. Those on slow cable, like the collision-heavy @home network, or those with fast downstream only, were still marked among the ranks of the elite.

Now we can properly categorize people regardless of their ISP or method of connecting to the Internet. We have a number. If you are less than 150, you're an LPB. Otherwise, you're just a p1ngk1dd13.

It's kinda like penis length, really. It doesn't matter at all in the grand scheme of things, but it's nice to have a number to compare yourself to.

Conditioning, and reflexes.

[re-Verse]

I figure a lot of it has to do with a) what we are used to. And b) how fast we are as people.

If you play at a lan party all weekend, and go home to your 80 ping, you swear you're playing in mud. Your rails are off, everything feels Wonky. And yet you may, if you're like me, remember a time where you were Completely comfortable living inside of a 250 ping. 'Getting inside of your lag' we'd say. And after 6 or 8 hours playing quake at 250 ping, eveything in real life seemed a little off, like it would be ok if you could adjust the latency a little :)

The other thing is, some people are just slower than others. If you're kinda slow, then you might not notice the difference between 150 and 200ms, simply becasue your body doesn't work like that. On the other hand, i know some squirril-people that may be able to detect network latency differences within a few ms no problem.

So i dunno. I guess the article is talking about a law of averages, but i think there is a lot more to consider.

Re:Ping isn't a QoS issue

[electricmonk]

Ping times no longer measure network speed except in very highly congested networks.

Oh, you mean like the Internet?

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