onstat -g sch , Busy Waits ?
Hi, Could anyone explain what may cause a large number of 'busy waits' ? Informix Dynamic Server Version 7.30.UC5 (HPUX-11.00) VP Scheduler Statistics: vp pid class semops busy waits spins/wait 1 1495 cpu 29 31 967 2 1508 adm 0 0 0 3 1509 cpu 280334 280893 999 4 1510 lio 2 0 0 5 1515 pio 2 0 0 6 1517 aio 19 0 0 7 1522 msc 1287 0 0 8 1524 aio 14 0 0 -----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own
darren_m_rogers@my-dejanews.com wrote: > Hi, > > Could anyone explain what may cause a large number of 'busy waits' ? > > Informix Dynamic Server Version 7.30.UC5 (HPUX-11.00) > > VP Scheduler Statistics: > vp pid class semops busy waits spins/wait > 1 1495 cpu 29 31 967 > 2 1508 adm 0 0 0 > 3 1509 cpu 280334 280893 999 > 4 1510 lio 2 0 0 > 5 1515 pio 2 0 0 > 6 1517 aio 19 0 0 > 7 1522 msc 1287 0 0 > 8 1524 aio 14 0 0 > For vp 3 (a cpu vp) it has does a busy wait 280893 times. This counter isincremented once for every time the last running thread on this vp yields, and when this vp checks to see if there are any threads it can run, but upon checking, it finds that there are no threads it can run. So instead of automatically doing some operation which would take it off of the physical cpu of the machine, it performs a spin type operation and when done if there is still nothing for it to do, it will then yield the physical cpu and wait to be woken up by an vp when it has something to do, or if it does find a thread to run, it will run it. Jacques ******************************************************************** * Jacques P. Renaut "I'd dazzle you with brilliance * * Informix Advanced Support if I only had the knack..." * * email: jrenaut@informix.com #include <disclamier.h> * ********************************************************************
In article <78kcue$kng$1@nnrp1.dejanews.com>, darren_m_rogers@my-dejanews.com wrote: > Hi, > > Could anyone explain what may cause a large number of 'busy waits' ? > > Informix Dynamic Server Version 7.30.UC5 (HPUX-11.00) > > VP Scheduler Statistics: > vp pid class semops busy waits spins/wait > 1 1495 cpu 29 31 967 > 2 1508 adm 0 0 0 > 3 1509 cpu 280334 280893 999 > 4 1510 lio 2 0 0 > 5 1515 pio 2 0 0 > 6 1517 aio 19 0 0 > 7 1522 msc 1287 0 0 > 8 1524 aio 14 0 0 > > -----------== Posted via Deja News, The Discussion Network ==---------- > http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own > This is probably not a big deal. When a cpu vp has no work to do, it will go into a busy wait so that UNIX does not swap the process out. After roughly 1000 spins, the vp will check again. At this point, if there is still no work to be done, a semop is performed and UNIX swaps the cpu vp process out to the UNIX queue. If your system is relatively inactive, this is nothing to worry about as your primary cpu vp is handling most of the work. If your system is loaded, however, this could be indicative of a lower level problem. Hope this helps. Bob ---------- -----------== Posted via Deja News, The Discussion Network ==---------- http://www.dejanews.com/ Search, Read, Discuss, or Start Your Own