Re: [patch] vmfixes-2.4.0-test9-B2 - fixing deadlocks

Christoph Rohland
2000-09-27T16:56:42Z

Andrea Arcangeli <andrea@suse.de> writes:

> On Wed, Sep 27, 2000 at 10:11:43AM +0200, Christoph Rohland wrote:
> > I just checked one oracle system and it did not lock the memory. And I
>
> If that memory is used for I/O cache then such memory should
> released when the system runs into swap instead of swapping it out
> too (otherwise it's not cache anymore and it could be slower than
> re-reading from disk the real data in rawio).

Yes, but how does the application detect that it should free the mem?
Also you often have more overhead reading out of a database then
having preprocessed data in swap.

> > Customers with performance problems very often start with too little
> > memory, but they cannot upgrade until this really big job finishes :-(
> >
> > Another issue about shm swapping is interactive transactions, where
> > some users have very large contexts and go for a coffee before
> > submitting. This memory can be swapped.
>
> Agreed, that's why I said shm performance under swap is very important
> as well (I'm not understimating it).

fine :-)

Greetings
Christoph