Re: how is data cached in the memory when using loop device

[Newsmail <newsmail@satimex.tvnet.hu>]

I'm using the -ac kernels, with riels VM. unfortunately that vm is not 
documented at all, I have no idea how it works exactly. I'm trying to tune 
a bit bdflush maybe if would help, but I didnt have too much succes yet 
with it.
regards,
greg

ps: what is the loop helper thread?

At 14:15 2002. 08. 27.دف', you wrote:
>Newsmail wrote:
> > I have an aes128 partition, I use loop-aes. I would like to ask, that when
> > linux caches the data prior to disk write, does it cache it in its
> > encrypted form or in plain?
>
>Data is cached in unencrypted form.
>
> > because, many times when I have big disk i/o
> > the machine seems to freeze for some seconds. I think that this is because
> > bdflush begins to write out cached plain data from memory, and encrypts all
> > in once, which results in this sort of freeze. is that right?
>
>Yes.
>
>Loop helper thread will release CPU pretty quickly if scheduler says it
>should reschedule. Ingo Molnar's new scheduler gives loop helper thread
>(that does time consuming encryption) much more CPU time than mainline
>scheduler.
>
>Problem may also be that large number of dirty RAM pages are unavailable for
>other use until their contents are encrypted and transferred to disk. RAM
>shortage causes delays in program execution.
>
> > ps: if anybody experienced this before, did he found any remedy for the 
> problem?
>
>What kernel version are you using? -ac and -aa kernels have better VM than
>mainline kernels.
>
>Regards,
>Jari Ruusu <jari.ruusu@pp.inet.fi>


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