One thing Vic, I learned from Rob a couple weeks ago. For some reason, servers using QDIO, CTC, etc (Other than IUCV).do not drop from queue, thus go into queue 3, thus do not get their storage trimmed. This is of course badness. As Rich pointed out, to see if the timer patch is working, look at the CPU utilizatin. But because of queue drop issue, q3 is not the method of detection. Hopefully Endicott can come up with a better approach to allow storage trimming....
>From: Vic Cross <[EMAIL PROTECTED]> > >G'day all, > >Just went through the process of building a new 2.4.19 kernel >with timer patch applied (linux-2.4.19-timer-1-may2002 from >DevWorks). I wonder if anyone has seen the >/proc/sys/kernel/hz_timer pseudofile, and can describe its >function. > >Full story, read on... > >When building the kernel, I noticed a new option: > > [*] No HZ timer ticks in idle > [ ] Idle HZ timer on by default <-- new one > >I read this as "do you want to enable the no-HZ function in your >kernel, but turn it off by default at IPL-time". Based on this, >I left it as shown above for my kernel build (because I wanted >the patched function, not the old function). > >After I IPLed, IND Q EXP told me that my idle guest was still >constantly sitting in Q3. Then I thought about the new kernel >option, and theorised that if there's an option that allows you >to set the default operation at IPL time there's likely to be a >way to change it while running... > >A brief search yielded /proc/sys/kernel/hz_timer, which was set >to 1. I echoed 0, and the system still worked, but still seemed >to be constantly active in Q3. Looking at the patch file it >would appear that it shoud be 0 to enable the 'no-HZ' function, >but it's not clear (to me, at least). "If you can't measure it, I'm Just NOT interested!"(tm) /************************************************************/ Barton Robinson - CBW Internet: [EMAIL PROTECTED] Velocity Software, Inc Mailing Address: 196-D Castro Street P.O. Box 390640 Mountain View, CA 94041 Mountain View, CA 94039-0640 VM Performance Hotline: 650-964-8867 Fax: 650-964-9012 Web Page: WWW.VELOCITY-SOFTWARE.COM /************************************************************/
