If you are talking about what is actually residing on the swap device, then I would agree with you. And from the perspective of z/VM and VDISK, you would also be right. But the question was asking about what *Linux* thought was out there. The idea was that Linux thought that 100 paging slots were *in use* and could not have other pages written in to them. I still say that would not be the case. If you could examine the control blocks, Linux would think those 99 other slots were available for use.
Mark Post -----Original Message----- From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of Barton Robinson Sent: Monday, February 28, 2005 4:55 PM To: [email protected] Subject: Re: Anyone running WebSphere under Linux on z/Series AND using ws admin scripts for application deployment? Sorry Mark, I would have to say YES, there are 99 stale copies.... I assume these are virtual disks? And you measure from z/VM, and not Linux? If measuring from Linux and the swap full goes up, then you have a "swap cancer" and that is bad. Linux uses a moving cursor algorithm for swap space allocation. You have done the right thing by having 3 swap disks, prioritized. I think it was Rob van der Heij that came up with this technique. BUT, they may be - or likely are too large. The moving cursor algorithm will allocate all of the first disk, and then go back and re-use it until it is full, then ONLY when the first disk is full, the second disk will be utilized. Thus the optimum configuration is for the first swap disk to be the correct size at peak period. The second disk is just for occassional overflow. If the first disk is too large, then you WILL have 99 stale copies. If sized correctly, then linux will write over the old ones. Look at the Linux data to understand the maximum that Linux thinks it has allocated as swap. That is the size of the first virtual disk.... >I would have to say no, you don't have 99 stale copies taking up paging >slots. > > >Mark Post > >-----Original Message----- >From: Linux on 390 Port [mailto:[EMAIL PROTECTED] On Behalf Of >James Melin >Sent: Friday, February 25, 2005 11:45 AM >To: [email protected] >Subject: Re: Anyone running WebSphere under Linux on z/Series AND using >wsadmin scripts for application deployment? > > >From what I've read this morning, I think I am being victimized by the >2.4 kernel design, as far as swapping is concerned. > >If I have 3 swap volumes: > >pequot:~ # swapon -s >Filename Type Size Used Priority >/dev/dasde1 partition 1201576 0 -1 >/dev/dasde2 partition 1202392 0 -2 >/dev/dasda1 partition 801256 0 -3 > >When will the operating system attempt to clean up swap? When all three >swap spaces are filled? If I swap out a page, swap it in again, swap it >out again, and in again... lets say I do this 100 times.... do I have >99 'stale' copies of the page on the swap volume? "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 /************************************************************/ ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390 ---------------------------------------------------------------------- For LINUX-390 subscribe / signoff / archive access instructions, send email to [EMAIL PROTECTED] with the message: INFO LINUX-390 or visit http://www.marist.edu/htbin/wlvindex?LINUX-390
