-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 The Thursday 2005-12-29 at 19:07 -0900, Greg Wallace wrote:
So when are the binaries cached, when you exit the program?
No, any file read from disk is cached the first time it is loaded. I don't really know if the method is to cache based on disk sectors doing read-ahead, or if it is file based, or a mixture: I'm not a kernel developer ;-) Once in cache it stays there unless the memory is needed for something else more necessary
I've really never explored this in Linux, but on 'dose, the application binary is cached the first time you open it. That's why if you open something like, say, EXCEL, turn right around and close it, then open it again, it comes up almost instantly the second time. You can also go to task manager and watch the memory hits. If an app is, say, 100K, the first time you open it you take a 200K memory hit. If you close it, memory goes down by 100K (leaving the 100K cached copy). The only time that cached copy would go away is if you needed the memory for some other app. Then it would be aged out. Does Linux work differently?
No, that's the idea. Details might be different, of course. I know that Linux uses all available memory not used for something else as cache. What I remember of windows internals, the memory reserved for cache was fixed: time ago there was a direct map (almost) from disk to cache. I'm not sure nowdays what it does. MsDos had no cache, it was an add on by third parties at first; so they must be using a quite complex method now. You may access the disk directly bypassing the system: what happens to the cache then? Linux is diferent, you access a virtualized filesystem, not the real filesystem below. - -- Cheers, Carlos Robinson -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.0 (GNU/Linux) Comment: Made with pgp4pine 1.76 iD8DBQFDtdMStTMYHG2NR9URAmKAAJsH8aKUdg+ta5RYK7Y4MIhnoXpJDQCfaG1M W2Rn9jPwI40HPCjozr1Lp5g= =Zt3O -----END PGP SIGNATURE-----