After I installed everything I needed, Ubuntu became slower and slower. I uninstalled some things and it became little bit faster but still wasn't fast. I did a fresh installed of Ubuntu 13.04 and formatted 12.10 then installed Ubuntu 13.04 since 12.10 was getting slow.
What are your tips for improving overall system performance on ubuntu? Inspired by this  I realized that some default settings may be rather conservative on Ubuntu and that it's possible to tweak it with little or no risk if you wish to make it faster.  This is not meant to be application specific (e.g. make firefox load pages faster), but system wide.  Preferably 1 tip per answer, with enough detail for people to implement it.  A couple of mine would be:   Install  (via Software Center or sudo apt-get install preload); Change  value - "which controls the degree to which the kernel prefers to swap when it tries to free memory";   What are yours?  PS: Since this is not intended to have a unique answer but rather, several useful tips, I'm making this community wiki out-of-the-box.
Is there a more complete way of proving this theorem (that I devised)? OR does this theorem already exist and have a name? Last night, I was working on re-solidifying my understanding of parametric equations, and came up with a neat trick for evaluating certain definite integrals. I'm not sure if it exists as a formal theorem, though I refuse to believe I'm the first to notice such a relation. The 'theorem' is a useful trick to evaluate the definite integral of a continuous function over an interval where the function is either strictly increasing or strictly decreasing, given that the inverse of the function is 'nicer' to work with than the function itself. My idea goes as follows:  If $y = f(x)$ is a continuous function over the interval $I$, and either:  $f'(x) &gt; 0$   OR   $f'(x) &lt; 0$   for all values of $x \epsilon I$, then:  $\int_{a}^{b}{f(x)dx} = bf(b) - af(a) - \int_{f(a)}^{f(b)}{f^{-1}(x)dx}$  where $a,b \epsilon I$  Quasi-proof:  Clearly, if a function is strictly increasing or decreasing, it is injective. This is clear because no two values in the domain can correspond to a single value in the range. I feel intuitively that it must also be surjective (though I'm not entirely sure how to prove this part). Assuming it is both injective and surjective over $I$, the function must have an inverse.   If we were to draw two rectangles out of our bounds, they will have areas:  $af(a)$ and $bf(b)$, so that   $bf(b) - af(a)$ will be the area of the region we are observing.  This area is equivalent to the sum of the areas connecting the curve $f(x)$ to the $x$-axis and to the $y$-axis. Thus:  $bf(b) - af(a) = \int_{a}^{b}{f(x)dx} + \int_{f(a)}^{f(b)}{f^{-1}(x)dx}$  Solving for $\int_{a}^{b}{f(x)dx}$, we get:  $\int_{a}^{b}{f(x)dx} = bf(b) - af(a) - \int_{f(a)}^{f(b)}{f^{-1}(x)dx}$  A particularly illuminating example is evaluating:  $\int_{a}^{b}{ln(x)dx}$  $ln(x)$ is strictly increasing over any interval, so the 'theorem' applies.  $\int_{a}^{b}{ln(x)dx} = bln(b) - aln(a) - \int_{ln(a)}^{ln(b)}{e^xdx}$  $\int_{a}^{b}{ln(x)dx} = ln(b^b/a^a) - (e^{ln(b)} - e^{ln(a)})$  $\int_{a}^{b}{ln(x)dx} = ln(b^b/a^a) + a - b$  and so we've evaluated the integral without the need of integrating the function itself (by method of integration by parts), but rather by integrating its inverse, which is trivial to evaluate.!  Response to Jason DeVito's answer: [This image was taken from   () Number of ways in which $5$ boys and $5$ girls are ordered in such a way that exactly $4$ girls stand consecutively in the queue Let $n$ be the number of ways in which $5$ boys and $5$ girls can stand in a queue in such a way that all the girls stand consecutively in the queue. Let $m$ be the number of ways in which $5$ boys and $5$ girls in such a way that exactly $4$ girls stand consecutively in the queue. Then find $\frac{m}{n}$.    I could find $n$ correctly as $6!\times 5!$, but I am finding $m$ as $7!\times 4!\times \binom{5}{1}$, but the book says $m$ is $6!\times 4!\times 5\times \binom{5}{4}$. Where have I gone wrong? What is the proper logic to find $m$? When and how did "momentarily" come to mean "in a moment", rather than "for a moment"? "Momentarily" used to mean "for a moment" only, and not "in a moment". Thus, newscasters could be divided into two clear groups: those who would say "we'll be back momentarily," and those who would not.  This restriction made sense to me, because having both definitions would promote ambiguity if a unique interpretation could not always be derived from the context. But in recent years it seems "momentarily" is regularly, maybe even more often, used to mean "in a moment" by newscasters of every caliber, and in fact this is even shown to be the definition when looked up in most dictionaries.  When did this word's meaning change? How did it come about? My exterior door deadbolt has gotten stuck - it'll open with the lever but not the key. By spraying WD-40 inside the lock, I've been able to get it to work but it's very stiff. I'd like to remove the lock and inspect the inside, either to clean/lube it or replace it. But I can't figure out how to remove the lock; there's no obvious way to do this. (I'm used to seeing two screws on the inside of the deadbolt, usually under the lever arms when it's horizontal.)    How do I remove this? I can loosen the cover plate on the inside but it doesn't do anything other than rotate a few degrees. Add CSS or JavaScript files to layout head from views or partial views Derivation of the formula for Ordinary Least Squares Linear Regression How was the formula for Ordinary Least Squares Linear Regression arrived at?  Note I am not only looking for the proof, but also the derivation. Where did the formula come from? Significance of the second focus in elliptical orbits 1.In classical mechanics, using Newton's laws, the ellipticity of orbits is derived. It is also said that the center of mass is at one of the foci.   2.Each body will orbit the center of the mass of the system.  My question is : Are the assumptions in 1 and 2 correct?   Follow up question : Assuming the distance from the centre of the mass to each body remains the same, do we have two bodies orbiting the centre of the mass of the system in an elliptical or circular orbit?   Finally : With elliptical orbits, if the heavier mass is supposed to be in one of the foci, if there is any significance to second focus, what is it? Is it a Lagrange point by any chance or does it have some other mathematical property? Integral $\int_{\frac{1}{2}}^1 \frac{\ln x}{\sqrt{x^2+1}}dx$ As human beings, we observe the world in which we live in three dimensions. However, it is certainly theoretically possible that more dimensions exist.  Is there any direct or indirect evidence supporting a fourth dimension? Add a confirmation before moving comments to a chat E: dpkg was interrupted... run 'sudo dpkg --configure -a' I was running an upgrade with the apt-get command, and it was taking an exceptionally long time because half way through my ISP hit me in the face with their fair usage policy.   After sitting outside &amp; watching the rain for awhile my electronics regained consciousness, so I went back to complete the upgrade and my terminal scolds me with   "E: dpkg was interrupted, you must manually run 'sudo dpkg --configure -a' to correct the problem."   The last bit of legible info was all this:  Installing (ri/RDoc) documention for (stuff and such) ERROR:  Could not find a valid gem 'watobo-0.9.8.724.gem' (&gt;= 0) in any repository rm: cannot remove `watobo-0.9.8.724.gem': No such file or directory  Setting up metasploit (4.3.0-bt1) ... Upgrading Pre-Existing Installation... /opt/metasploit/postgresql/scripts/ctl.sh : postgresql  (pid 1191) already running prosvc is running metasploit is running [*] [*] Attempting to update the Metasploit Framework... [*]   So on it goes for miles, talking about gem caches, rubies, &amp; stuff I wish I had. All up until:  A    lib/gemcache/ruby/1.9.1/gems/state_machine-1.1.2/gemfiles/active_record-2.1.2.gemfile.lock   ...and there it has sat, all night.    If I stop it, will I still get the dpkg error (on the off chance that I won't), or if so what do I need to to resume using apt-get commands and its Super Cow Powers? For a polynomial $p(z)$, prove there exist $R>0$, such that if $|z|=R$, then $|p(z)|\geq |a_n|R^n/2$ Texture messes up after extruding a modified plane I need to use filter to sort calendar months in mmm format.  Data &gt; Sort &gt; Custom will do it but I cannot make filter work. Months are in a column eg SEP, APR, JAN, APR, etc.  Filter just does an alphabetical sort so it puts all the APR first. Fixed point, union of $\aleph_0, \aleph_{\aleph_0},\aleph_{\aleph_{\aleph_0}}\dots$ [see Noah's comment on notation] force long text inside \item[{\texttt{}] to wrap How to use -exec option in find command I wanna solve some problems in compiz with my brain and hands.  By the way I entered following command to build compiz from source in Ubuntu 12.04  find /opt/compiz-built/share/gconf/schemas -exec gconftool-2 --install-schema-file={};   I referred that command at   And following message is shown.  How to use -exec option in find command, I guess that it's my mistake. ATI Radeon HD 7770 no GPU rendering? While executing an INSERT statement with many rows, I want to skip duplicate entries that would otherwise cause failure. After some research, my options appear to be the use of either:  ON DUPLICATE KEY UPDATE which implies an unnecessary update at some cost, or INSERT IGNORE implies an invitation for other kinds of failure to slip in unannounced.  Am I right in these assumptions? What's the best way to simply skip the rows that might cause duplicates and just continue on to the other rows? Why I cannot use universal instantiation rule here? I have the following premise:      $$\forall x (Fx \vee \neg Fx) \rightarrow Ga$$   Why I cannot use UI and get: $(Fa \vee \neg Fa) \rightarrow Ga$ And what is the difference between the first premise and the below premise:     $$\forall x ((Fx \vee \neg Fx) \rightarrow Ga)$$   Thanks in advance.