Re: can shared cache be swapped to disk?

On Sat, Dec 18, 2010 at 10:11 PM, flyusa2010 fly <flyusa2010@gmail.com> wrote:
> hi, folks!
> I see that shared cache is implemented by system v shared memory. I wonder
> whether data in this area can be swapped out to disk.
> Isn't it bad that we read data from disk, put data in shared cache, and
> finally data in shared cache is swapped to disk again!
> Why not use shmctl(..SHM_LOCK..) to pin data in main memory?
> Thanks!

I've tried that on a recent linux kernel, to see if it would allow
shared_buffers to usefully be a large fraction of total memory.  It
didn't help.  So either swapping wasn't the problem in the first
place, or the kernel ignores the order.

Cheers,

Jeff