drop CPU VPs....

Hi, ifx 11.50 FC8 - AIX 6.1 I'm trying remove some CPU VPs and not able to do... Some VPs was dropped. When the message "cannot drop..." appear, no more VPs are dropped. This is part of a "test tuning" what we executed on our production, where grow from 16 to 112 CPUs VPs and now need to back to 16 again. Now still have 70 VPs and just don't drop... 10/25/11 13:26:52 Logical Log 83496 - Backup Started 10/25/11 13:26:52 Logical Log 83496 - Backup Completed 10/25/11 13:28:13 *** _aiostop(): Pid = 6881608 10/25/11 13:28:15 *** _aiostop(): Pid = 9240606 10/25/11 13:28:16 Cannot drop the VP as a thread hard bound to it 10/25/11 13:28:16 Cannot drop the VP as a thread hard bound to it 10/25/11 13:28:16 Cannot drop the VP as a thread hard bound to it 10/25/11 13:28:16 Cannot drop the VP as a thread hard bound to it Someone know if have some kind of approach to drop this CPUs without bounce the instance?? I'm trying : onmode -c block onmode -p -10 cpu onmode -c unblock Works on first try and second try... but, after that... just "cannot drop..." messages... Cesar

Hi, once a CPU-VP has been started it may take over an important task that cannot be dismissed and therefore the CPU-VP cannot be dropped. E.g. the Admin Guide says: If you attempt to drop a CPU virtual processor that is running a poll thread, you receive the following message: onmode: failed when trying to change the number of cpu virtual processor by -number. Possibly there are other tasks that cause such a situation. Certain tasks in the server usually are performed by threads. Opposed to POSIX threads, the threads running in the Informix VPs are a homegrown implementation (that was started long ago, when POSIX threads were not yet available, at least not on all the platforms supported by Informix at the time). Therefore you have to execute a command like "onstat -g ath" (ath -> all threads) to see all the existing threads. The output of this command will also tell you, on which VP a particular thread is running. With this info you should be able to figure out, why you cannot drop those remaining CPU-VPs. Regards, Martin -- Martin Fuerderer IBM Informix Development Munich, Germany Information Management Read about the Informix Warehouse Accelerator: http://tinyurl.com/the-iwa-blog IBM Deutschland Research & Development GmbH Chairman of the Supervisory Board: Martin Jetter Board of Management: Dirk Wittkopp Corporate Seat: Boeblingen, Germany Reg.-Gericht: Amtsgericht Stuttgart, HRB 243294 ids-bounces@iiug.org wrote on 10/25/2011 08:25:56 PM: > [image removed] > > drop CPU VPs.... [25279] > > Cesar Inacio Martins > > to: > > ids > > 10/25/2011 08:26 PM > > Sent by: > > ids-bounces@iiug.org > > Please respond to ids > > Hi, > > ifx 11.50 FC8 - AIX 6.1 > > I'm trying remove some CPU VPs and not able to do... > > Some VPs was dropped. When the message "cannot drop..." appear, no more VPs > are dropped. > > This is part of a "test tuning" what we executed on our production, where grow > from 16 to 112 CPUs VPs and now need to back to 16 again. > Now still have 70 VPs and just don't drop... > > 10/25/11 13:26:52 Logical Log 83496 - Backup Started > 10/25/11 13:26:52 Logical Log 83496 - Backup Completed > 10/25/11 13:28:13 *** _aiostop(): Pid = 6881608 > 10/25/11 13:28:15 *** _aiostop(): Pid = 9240606 > 10/25/11 13:28:16 Cannot drop the VP as a thread hard bound to it > 10/25/11 13:28:16 Cannot drop the VP as a thread hard bound to it > 10/25/11 13:28:16 Cannot drop the VP as a thread hard bound to it > 10/25/11 13:28:16 Cannot drop the VP as a thread hard bound to it > > Someone know if have some kind of approach to drop this CPUs without bounce > the instance?? > > I'm trying : > onmode -c block > onmode -p -10 cpu > onmode -c unblock> > Works on first try and second try... but, after that... just "cannot drop..." > messages... > > Cesar > > > ******************************************************************************* > Forum Note: Use "Reply" to post a response in the discussion forum. >

Hi Martin, Few minutes after post this email here, I discovery exactly what you said, I just check which is the last CPU VP with "onstat -g glo" , use the "onstat -g cpu" to found all sessions what running more over it and killed only this session with more cpu utilization.. then I'm able to remove the CPU VP. I just consider this very very very impracticable on production environments because is more and more common the requirement to execute all mantaince / tunning over the database online, without bounce it or kill user sessions. I open a PMR to request this as new feature... some way where the engine "force out" the thread from the cpu vp and keep the administration of the database able to do with 100% flexibility for tunning... thanks for your answer, help me to confirm about the behave of this situation "drop cpu vp". Regards Cesar On 26/10/2011 06:01, Martin Fuerderer wrote: > Hi, > > once a CPU-VP has been started it may take over an > important task that cannot be dismissed and therefore > the CPU-VP cannot be dropped. E.g. the Admin > Guide says: > > If you attempt to drop a CPU virtual processor that is > running a poll thread, you receive the following message: > > onmode: failed when trying to change the number > > of cpu virtual processor by -number. > > Possibly there are other tasks that cause such a situation. > > Certain tasks in the server usually are performed by > threads. Opposed to POSIX threads, the threads running > in the Informix VPs are a homegrown implementation > (that was started long ago, when POSIX threads were > not yet available, at least not on all the platforms supported > by Informix at the time). Therefore you have to execute > a command like "onstat -g ath" (ath -> all threads) to see > all the existing threads. The output of this command will > also tell you, on which VP a particular thread is running. > With this info you should be able to figure out, why you > cannot drop those remaining CPU-VPs. > > Regards, Martin