RE: [SLE] OO: If you can make it, I can break it!



On Saturday, December 31, 2005 @ 2:04 AM, Carlos Robinson wrote:

>The Friday 2005-12-30 at 16:53 -0900, Greg Wallace wrote:

>> >Correct; but not only binaries, but everything.
>>
>> But just the read only portion is cached, right?

>No, also the write operations are cached. I understand that the kernel
>then sorts the pending write operations to try minimize disk head
>movements (I saw somewhere keywords to select the sorting algorithm). You
>can dissable write cache operations with the option "sync" in fstab; for
>example, if you automount media like floppies or external drives, they are
>normally mounted sync, so they can be removed fast: but they are slow when
>writing because the cache is dissabled, mounted sync.

>> (temporary storage holding values you input but not saved) is modified by
>> what you do while you're modifying a data file but that doesn't change
>> what's cached. The cached copy is just a blank slate, suitable for a
pure
>> memory to memory copy if you exit the app and then call it back up. I
>> wouldn't think that any special/seldom used forms would be loaded by
default
>> either, but would only be loaded if you actually went to one of those
during
>> your edit session. Probably just the initial form that you see when you
>> start the app (and maybe a few commonly used ones) is loaded when you
call
>> up the app the first time.

>No, the cache doesn't know about forms or any application internals. It
>just copies the disk sectors or files into memory and operates there, in
>memory. If the cache is dirty, modified, then it will be saved to disk
>promptly, but not inmediately. It is not only binaries, but any file.

>For the exact details, you would have to ask a kernel developper :-)

>- --
>Cheers,
> Carlos Robinson

But if I exit an app and then call it back up, I don't want to have any
"data" from the previous execution. In order to get that so called clean
slate, the app has to either get the clean slate (so to speak) from disk or
from cache. So, a clean copy should be in the cache ready to serve up if I
try to call the app up again later in my session. At least that's the way I
understand it to work in the 'doze world.

Greg Wallace



--
Check the headers for your unsubscription address
For additional commands send e-mail to suse-linux-e-help@xxxxxxxx
Also check the archives at http://lists.suse.com
Please read the FAQs: suse-linux-e-faq@xxxxxxxx



Relevant Pages

  • Re: What can I check to fix system performance?
    ... it seems you have plenty of memory available: ... copies of files you have read of written lately, in a cache, in case ... processes per CPU, or 40 in all. ... Consider the disk structure. ...
    (comp.os.linux.setup)
  • Re: Caching control
    ... |> | invalidate/unmap them in order to discard the data from memory. ... |> writing out to disk. ... | easy to discard as clean disk cache. ... stating that a specific amount of RAM can be used only for I/O ...
    (comp.os.linux.development.system)
  • Re: Scheduler: Process priority fed back to parent?
    ... > interactivity cache could estimate interactivity over a period of hours ... Then you don't even have to write it to the filesystem. ... For those of us with enough memory or a large variety of programs, ... That way the file is already in disk cache or on its way when the ...
    (Linux-Kernel)
  • Re: [PATCH 0/8] zcache: page cache compression support
    ... slowdown as reading a page from disk can take time in order of milliseconds. ... Memory compression increases effective memory size and allows more pages to ... We use them to implement a 'second chance' cache ...
    (Linux-Kernel)
  • Re: FreeBSD and poor ata performance
    ... Linux doesn't really have raw disk devices. ... All disk I/O is through the disk cache, ... performance (on a system with sufficient memory to hold all of the data ... sys 0m12.477s ...
    (freebsd-questions)