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Old 11-26-2012, 12:59 AM   #16
Elv13
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Prelinking do work, but on modern CPU, the performance difference in non-existant. When I talk about PGO, lets take for example Firefox, it start many time faster on windows (32bit) than Linux (32bit), this is because of PGO. It is also why it run faster on Windows. PGO take actual execution data into account when wiring code paths. That really make a big difference, up to 50% when done well, something that is very hard.

If you want to maximize performance, Gentoo is still the only effective way, but for the average Linux user without deep compiler understanding, it end up being trials and errors, mostly errors. In your case, the -Os, aggressive use flags, --as-needed (default), LTO, PGO and a lot of other optimization will make apps start faster.
 
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Old 11-26-2012, 11:58 AM   #17
Rookie1337
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Quote:
Originally Posted by Elv13 View Post
Prelinking do work, but on modern CPU, the performance difference in non-existant. When I talk about PGO, lets take for example Firefox, it start many time faster on windows (32bit) than Linux (32bit), this is because of PGO. It is also why it run faster on Windows. PGO take actual execution data into account when wiring code paths. That really make a big difference, up to 50% when done well, something that is very hard.

If you want to maximize performance, Gentoo is still the only effective way, but for the average Linux user without deep compiler understanding, it end up being trials and errors, mostly errors. In your case, the -Os, aggressive use flags, --as-needed (default), LTO, PGO and a lot of other optimization will make apps start faster.
That sucks. I just have to ask though...are PGO and all the other compiler optimizations really that effective? It wasn't until I started ramdisk usage in Windows that I really noticed a significant difference and that's what had me wondering if I could somehow replicate a similar method for Linux.

So I just want to make sure...there's no way I could copy /usr/lib to another dir for a moment; mount /usr/lib as a tmpfs; copy the contents to the tmpfs mounted /usr/lib and still have programs work?
 
Old 11-26-2012, 12:52 PM   #18
Elv13
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If it was that effective and magically magic, it would be enabled by default. That said, yes, it is possible to get more performance out of thin air with those kind of optimizations, but it require knowledge, will power and time to tweak it. It also need a fast CPU in the first place, because compiling and testing, as automated as it is in Gentoo, still take CPU time, lots of it. Loop parallelization make some packages up to 30% faster, so does fastmath, but will break some other packages.

Last edited by Elv13; 11-26-2012 at 12:53 PM.
 
Old 11-26-2012, 03:39 PM   #19
Rookie1337
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Originally Posted by Elv13 View Post
If it was that effective and magically magic, it would be enabled by default. That said, yes, it is possible to get more performance out of thin air with those kind of optimizations, but it require knowledge, will power and time to tweak it. It also need a fast CPU in the first place, because compiling and testing, as automated as it is in Gentoo, still take CPU time, lots of it. Loop parallelization make some packages up to 30% faster, so does fastmath, but will break some other packages.
Alright. Thanks. So the solutions are any/all of the following a) learn Gentoo and it's compiling options b) choose a distro like SLAX/Porteus c) get an SSD. Thanks for the help guys. I guess this one is solved.
 
  


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