On Thu, Feb 12, 2009 at 2:24 AM, Frank Swarbrick <[email protected]> wrote:
> We also have migrated some WebSphere stuff to Z and apparently it's noticably > slower as well, especially "start up". A lot of performance issues that are casually attributed to "System z" are actually virtualization issues. When you share a resource, you have to behave social. Applications developed on/for discrete servers often follow a different strategy (if any). We did identify a (design) issue in JVM 5 that will make Java applications use more CPU when starting in a CPU constrained environment. Note that this is "double bad luck" - not only does it take longer to get your share of CPU, the Linux server also requires more CPU because there is less available :-( <img src=death-spiral.jpg> The problem is most visible in the startup of large application servers with many deployed applications. Some Web Application Servers are more complicated than necessary when the application developers left all kind of additional (sample) applications in after they finished playing with it. Without instrumentation it is hard to confirm, but when you notice that starting different Linux servers after each other takes in total less time than starting them in parallel, then you're probably impacted by it. Rob -- Rob van der Heij Velocity Software http://www.velocitysoftware.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
