Here's my DNS histograms. I visited cnn.com, bbcnews.com, news.com.
All three sites took an extremely long time to load, and the first two
sites failed DNS lookup the first time, I had to hit the refresh
button. I'm using Vmware Fusion 2 running windows XP, Chrome
1.0.154.48, with OpenDNS as DNS host. I do not see a problem with
"Use DNS pre-fetching to improve page load performance" turned off
under Vmware, and I also do not see this problem in non-vmware
environment on my other windows XP laptop.
Histogram: DNS.PrefetchCacheEviction recorded 4 samples, average =
8987.0, standard deviation = 8090.6 (flags = 0x1)
0 ...
533
------------------------------------------------------------------------
O (1 = 25.0%) {0.0%}
633 ...
3553
------------------------------------------------------------------------
O (1 = 25.0%) {25.0%}
4222 ...
8416
------------------------------------------------------------------------
O (1 = 25.0%) {50.0%}
10000
------------------------------------------------------------------------
O (1 = 25.0%) {75.0%}
Histogram: DNS.PrefetchFoundNameL recorded 28 samples, average =
5403.7, standard deviation = 3934.2 (flags = 0x1)
0 ...
539 --------------
O (1 = 3.6%)
{0.0%}
730 --------------
O (1 = 3.6%)
{3.6%}
989 -----------------------------
O (2 = 7.1%) {7.1%}
1340 --------------
O (1 = 3.6%)
{14.3%}
1816 -------------------------------------------
O (3 = 10.7%) {17.9%}
2460 -------------------------------------------
O (3 = 10.7%) {28.6%}
3333
------------------------------------------------------------------------
O (5 = 17.9%) {39.3%}
4516 --------------
O (1 = 3.6%)
{57.1%}
6118
------------------------------------------------------------------------
O (5 = 17.9%) {60.7%}
8289 ----------------------------------------------------------
O (4 = 14.3%) {78.6%}
11230 -----------------------------
O (2 = 7.1%) {92.9%}
15215 ...
Histogram: DNS.PrefetchQueue recorded 32 samples, average = 527.7,
standard deviation = 992.4 (flags = 0x1)
0
------------------------------------------------------------------------
O (12 = 37.5%)
1 ------------------------------------------------
O (8 = 25.0%) {37.5%}
2 ------
O (1
= 3.1%) {62.5%}
3 ...
5 ------------------
O (3 = 9.4%)
{65.6%}
6 ...
752 -
O
(1 = 3.1%) {75.0%}
894
O
(0 = 0.0%) {78.1%}
1062 -
O
(1 = 3.1%) {78.1%}
1262
O
(0 = 0.0%) {81.3%}
1500 -
O
(1 = 3.1%) {81.3%}
1782 -
O
(1 = 3.1%) {84.4%}
2117 -
O
(1 = 3.1%) {87.5%}
2516 --
O
(2 = 6.3%) {90.6%}
2990 -
O
(1 = 3.1%) {96.9%}
3553 ...
Histogram: DNS.UnexpectedResolutionL recorded 27 samples, average =
4771.7, standard deviation = 6310.0 (flags = 0x1)
0
------------------------------------------------------------------------
O (6 = 22.2%)
1 ...
294 -------
O (3
= 11.1%) {22.2%}
398 --
O
(1 = 3.7%) {33.3%}
539 -------
O (3
= 11.1%) {37.0%}
730 --
O
(1 = 3.7%) {48.1%}
989
O
(0 = 0.0%) {51.9%}
1340 -----
O
(2 = 7.4%) {51.9%}
1816 ...
3333 -----
O
(2 = 7.4%) {59.3%}
4516 --
O
(1 = 3.7%) {66.7%}
6118 --
O
(1 = 3.7%) {70.4%}
8289 -----
O
(2 = 7.4%) {74.1%}
11230 ----------
O (4 =
14.8%) {81.5%}
15215
O
(0 = 0.0%) {96.3%}
20614 --
O
(1 = 3.7%) {96.3%}
27929 ...
On Feb 10, 9:41 am, Jim Roskind <[email protected]> wrote:
> Your browser is instrumented to reveal some data that would be helpful
> in understanding this performance. Since you're seeing times greater
> than 60 seconds, something big should show up. If possible, please
> visit (in chromium):
>
> about:histograms/DNS
>
> You'll see a pile of ASCII art histograms, which reflect what has been
> going on with regard to DNS fetching. None of the information should
> be very confidential, so if possible, please cut/paste/post a copy
> here for folks to look at.
>
> It may, for example, be that the DNS resolver in Vmware is restricting
> the the rate of resolutions, rather than allowing them to happen in
> parallel. Without taxing most computers or networks, Chromium
> currently tries to do up ot 8 resolutions in parallel. If this were a
> problem, then you'd see a large average queueing delay (as resolutions
> backed up into the queue) in the histogram labeled DNS.
> PrefetchQueue. The median for that histogram should be tiny (around
> 1ms), but the mean could be much larger if you visit pages with a LOT
> of domains (wikipedia comes to mind). Even so, I'd be rather
> surprised to hear about queuing delay over 1 second.
>
> As a second example, for some reason your DNS resolution time may be
> terrible. If so, you'd see this in the histogram labeled
> DNS.PrefetchFoundNameL (where I'd commonly expect to see a median
> value around 85ms, and mean value up closer to 200-600ms). If you see
> a long tail (resolutions larger than a second or two, meaning larger
> than 1000-2000ms along the axis on the left), then there may be a
> problem with your resolver or your network. I've seen especially long
> tails in negative results (host not found) on networks when netbios
> kicks in and does various work to broadcast in order to find local
> hosts.
>
> Again, please post a copy of your DNS histograms after you encounter
> this problem.
>
> Thanks,
>
> Jim
>
> On Feb 9, 8:06 pm, Bob Doe <[email protected]> wrote:
>
> > I'm running Chrome under Vmware Fusion 2.0. If I have "Use DNS pre-
> > fetching to improve page load performance" turned on, many websites I
> > visit seem to stall for a long time (> 60 seconds) at "Resolving
> > host..." before web pages are rendered. I have found other people on
> > the web complain about the same problem, what is the underlying cause,
> > and is there plan to fix this problem in upcoming releases?
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