backup – Any way to configure fsck_hfs to use more memory to speed up verification of Time Capsule images?

Periodically Time Machine verifies sparsebundle backups with fsck_hfs. When the sparsebundle is on a Time Capsule (TC) it does this by creating a partial and much smaller representation of the sparsebundle on the TC, transferring the result to the mac into

/private/var/db/com.apple.backupd.backupVerification 

and then running fsck_hfs on it locally (it mounts the local sparsebundle as can be seen with diskutil list).
The problem is that it takes a very long time for fsck_hfs to verify this representation of very large TC sparsebundles (e.g. >24hrs).

(This leaves the timemachine process showing in the menu as if it was stuck ‘verifying’ with the real Time Capsule disk apparently no longer mounted under /Volumes – which confuses many into thinking the process has died)

fsck_hfs is launched by its parent process backupd with the parameters -f -n -x -E . There are various posts about fsck_hfs working much more efficiently if allowed to use more memory (-c option). By default (at least on my system) it seems to be limited to 3Gb.

My question is, is there anyway to pass a config that might cause backupd to launch fsck_hfs with the additional (-c) parameter and so run faster?

statistics – Link between web page load speed and percentage of people leaving the web page

I’m working on a research paper in the field of Website Preformance and I’ve found an article that claims that 57% of people leave websites that take longer than 3 seconds to load. This article cites no source for this claim but I imagine it was done in some sort of study.

Another claim is in this article which says 53% of mobile users will leave a webpage if it doesn’t load in 3 seconds. They link to a page of google but not directly to the data and the only 53% figure I found on that website is this.

Here is a third article claiming 1 in 4 people abandon a website that takes more than 4 seconds to load. I found this page with an image (claim is at the top right of the image) but not an actual study.

Are there any studies that make a link between loading times and percentage of people leaving the page? Does anyone know of a paper that might relate to this?

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pathfinder 1e – Does having decent swim speed from spell, item, power, racial or class ability allow you to propel yourself out of the water?

This situation is covered under what should be the normal vertical jump rules. Just make sure you calculate based on water speed instead of base speed since above 30 speed gives bonus to check, while movement under gives a penalty.

So lets say the railing of the pirate ship is 10 feet above the surface of the water. Assuming your going to be moving under the water to take advantage of DC’s not doubling, you would need a acrobatics check of 40 (10 feet times 4 per foot).

There are no specific rules for jumping out of the water, and the normal rules for jumping don’t specific their only for land, which is why I have applied them. Even the 3pp rules on the page only cover jumping into water, not out of.

C++ Incredibly Precise Sorter | Efficiency and speed of sorting algorithms

Hey Guys,
I’m in the process of building a console program in C ++ that allows users to:

  • sort a sequence of numbers loaded from a TXT file
  • save sorted sequence in a new TXT file
  • measure the sorting time for individual algorithm

I decided to write such a program because I want to learn algorithms, how different sorting algorithms work and I was curious how efficient/fast each individual algorithm is.

At the moment I have implemented

  • Bubble Sort
  • Insertion Sort
  • IntroSort (from C++ STD)
  • Selection Sort
  • Merge Sort
  • Quicksort

This is a sample output of the program

   (Bubble Sort)  Took:  77817989 µs   (77817.989 ms) (77s) to sort 100000 numbers
(Insertion Sort)  Took:  24974911 µs   (24974.911 ms) (24s) to sort 100000 numbers
      (STD Sort)  Took:     33990 µs      (33.990 ms)  (0s) to sort 100000 numbers
(Selection Sort)  Took:  20961005 µs   (20961.005 ms) (20s) to sort 100000 numbers
    (Merge Sort)  Took:    364995 µs     (364.995 ms)  (0s) to sort 100000 numbers
     (Quicksort)  Took:     25993 µs      (25.993 ms)  (0s) to sort 100000 numbers

Here’s the code for the project on github, as there would be too much pasting on this page.

Okay, end of story about the project, I have a few questions for experienced programmers

  1. Could anyone do some little code review please?
    I wonder if I have built the project structure correctly. What could be changed in the code. What is coded incorrectly. What bad practices have I committed. e.t.c
  2. I wonder if the measurement results are reliable in any way. How the system speed or the order in which the sorting function is called affects the results
  3. I plan to implement even more sorting algorithms. In your opinion, what other features could I add to make the project more interesting and to impress the future employer?
  4. And one last thing. What is your honest opinion about this project?

Thank you very much in advance for any help

performance – Apple trackpad:getures not working fine when cursor speed is high

I’m new to magic trackpad 2, and I’ve been using a mouse with cursor speed set to maximum for about 15 years so far, so first thing I did when connecting the trackpad was realizing it needed a lot of movement of my finger to reach screen corners, so I entered the settings and set speed to max speed. Now I can move the cursor with small movement of my finger the same way I could move it with my mouse.

Then I started testing the famous “gestures” and most of them were not working. I thought it was a faulty trackpad bu then I lowered the speed and they started working. For instance, pinch to zoom in/out was almost impossible to make, and also showing the launchpad happened once every ten tries. Instead, the cursor moved somewhere.

Has anyone else experienced this and found some way to solve it? I have had to move the speed almost to original setting which, for my standards, it’s incredibly slow.

canvas – Javascript speed of an animated object (planet orbiting sun)

So I am pretty new to JavaScript and I thought I might make an animation demonstrating a planet orbiting a sun in an elliptical orbit using Kepler’s laws.

I am struggling to get the speed right. So I want the speed of the planet to be slower further away from the sun, and faster closer to the sun.

Within this method I use Keplers laws to calculate the x and y coordinate. I have also calculated the (real) velocity at each point in its trajectory (this may need to be scaled appropriately as I hope to use real astronomical data).

  this.position = function(theta) {
    var R = Math.pow(((Math.pow(T,2))/((4*Math.pow(Math.PI, 2))/(G*M))),(1/3)) ;
    var a = R/(1-e) ;
    var radius = a*(1-Math.pow(e,2))/(1+e*Math.cos(theta)) ;
    this.x = radius*Math.cos(theta)*10e-10 + canvas.width/2 ;
    this.y = radius*Math.sin(theta)*10e-10 + canvas.height/2;
    this.vel = Math.sqrt(G*M*((2/radius)-(1/a))) ;
    
  }

I’ve got full code on CodePen here: https://codepen.io/yasserqureshi/pen/VwPOEzL?editors=0011

Any help or comments will be appreciated. Thanks!

dnd 5e – Levitate rules and speed

This is what the spell description say about Levitate ending

When the spell ends, the target floats gently to the ground if it is still aloft.

This would imply that no matter the height, the target would just fall to the ground and take no damage. This could be intended to work similarly to Feather Fall.

Otherwise, if the spell is still active

You can change the target’s altitude by up to 20 feet in either direction on your turn.

Given that one turn is ~6 seconds, and the duration for the spell is “Up to 10 minutes”, if you maintain concentration for 10 minutes, you could move your target 2000 feet up. Given the limitations of the spell, you should at max be able to move a creature 200 ft per minute, regardless of direction.

movement – Does the speed of the Fly spell increase based on bonuses to my land speed?

Equal to your speed.

Not trying to be snide; it really is. From the Movement section(can’t remember page name)

Most characters and monsters have a speed statistic—also called land Speed—which indicates how quickly they can move across the ground. When you use the Stride action, you move a number of feet equal to your Speed. Numerous other abilities also allow you to move, from Crawling to Leaping, and most of them are based on your Speed in some way. Whenever a rule mentions your Speed without specifying a type, it’s referring to your land Speed.

So, it’s referring to your land speed, since it isn’t specified. Your flying speed is 40 feet, the same as your land Speed.