Chen, Kenneth W wrote:

> Can you do some stress test experiments and let us know how many time ptc.l
> was actually executed in vhpt_miss/tlb_miss/dirty/access
> handler? Thanks.

Here is a patch that adds a small syscall to display or clear (./stat -clear)
the statistics.
Please verify if this is what you wanted (and the potential bugs...).

The 1st version (indicated by "#if 0") I tried, should have worked in virtual
mode. Unfortunately, I could not make it work (having this short deadline).
Could you have a look at it why it fails to work?

I ran a "make -j 16" of the kernel on an 8 processor machine.
(It is actually 2 Tiger boxes connected via a Scalability Port Switch.)
Unfortunately, the I/O is subsystem weak: a single SCSI disk.

Here is what I got:

             VHPT miss counter: 1674978
       VHPT miss - hash purged:       0
        VHPT miss - PTE purged:       0
             ITLB miss counter:     293
            ITLB miss - purged:       0
             DTLB miss counter:    3806
            DTLB miss - purged:       0
            DIRTY trap counter:     224
                DIRTY - purged:       0
         I-ACCESS trap counter:       2
             I-ACCESS - purged:       0
         D-ACCESS trap counter:  173227
             D-ACCESS - purged:       0

Unless I am mistaken, there is no purge observed.
It is very much curious having so few dirty and i-access traps...

Have you got some good & stressing tests?

Zoltan