Re: Latch spin - OS timeslice

Hi, Kyle,

Why do you think CPU0 should take more load? We're all using symmetric multi-processor machines.

I've never seen srw (spins on reader-writer locks) showing anything other than 0. May be a bug in mpstat. Why do you expect sys time to be higher? I thought spins consumed user time, not sys time. Cross-processor calls (xcal), among other things, drive up sys time.

lockstat doens't allow you probe a process other than the command following lockstat. Usage is lockstat [options] command. Otherwise it would be the ideal tool. I don't know why they wrote this program this way. Unfortuntely the API for lockstat(7D) is not published.

Somebody in Oracle should know how long 1 latch get spin takes because the default _spin_count 2000 can't be an arbitrary number. Regards,

Yong Huang
yong321_at_yahoo.com

> I'd be interested in looking at the mpstat output for all processors. You
> should notice a higher smtx count for proc 0 being the master may be higher.
> But, a count of 100 is not a problem from what I have seen.
>
> Is the sys time from vmstat greatly higher than the user time?
>
> What does the mpstat column srw indicate. Is it a lot higher than the smtx
> col?
>
> Unfortunately I am not near a sun machine as I have been working on NT for a
> bit now, but from memory, the lockstat command "man lockstat" will dump all
> lock contention for you.
Received on Thu Mar 28 2002 - 11:48:20 CST