Up until 5.4, DCSS was not a serious solution as it was very limited - people tried it because it was cool, but dot com was cool too.
The performance of vdisk is well understood, we know how to minimize it's impact with multiple vdisks of smaller sizes, we know that it gets paged out when not referenced and we know when it gets paged out. With DCSS, will it be first fit, or moving cursor allocation? First fit is optimal, vdisk is moving cursor. DCSS should be paged out with the same rules as vdisk, but this needs to be verified in real life. The CPU savings are "obvious", but are we talking 1 percent of 1 percent of an IFL? Swapping at 1000 per second to vdisk used about 10% of an 890 CPU for reference. That is a pretty sizable target on an 890, not so sizeable on a z10, and nobody swaps at 1000 per second regularly. most installations swap even across 100 servers a total of less than 100 per second, with the average generally being less than 1. So if swap rate is high, then probably there is a configuration problem, and if swapping is low, what is the gain? Pieter Harder wrote:
Hi list, I am starting to think about the possibilities 2GB above the bar DCSS in z/VM 5.4 will provide for replacing large Vdisk swap. But I can't find any usable documentation on how to do swap to DCSS. The basics are documented on dw and I can probably manage, but when anyone has been there and done that can you please post some pointers and save us all the trouble of finding out again. Performance information is quite welcome as well. Best regards, Pieter Harder [EMAIL PROTECTED]<mailto:[EMAIL PROTECTED]> tel +31-73-6837133 / +31-6-47272537 Brabant Water N.V. Postbus 1068 5200 BC 's-Hertogenbosch http://www.brabantwater.nl Handelsregister: 16005077 ---------------------------------------------------------------------- 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
begin:vcard fn:Barton Robinson n:Robinson;Barton adr;dom:;;PO 390640;Mountain View;CA;94039-0640 email;internet:[EMAIL PROTECTED] title:Sr. Architect tel;work:650-964-8867 note:If you can't measure it, I'm just not interested x-mozilla-html:FALSE url:http://velocitysoftware.com version:2.1 end:vcard
