On Thu, 18 Oct 2007, Mike Gerdts wrote: > On 10/18/07, Bill Sommerfeld <[EMAIL PROTECTED]> wrote: >> that sounds like a somewhat mangled description of the cross-calls done >> to invalidate the TLB on other processors when a page is unmapped. >> (it certainly doesn't happen on *every* update to a mapped file). > > I've seen systems running Veritas Cluster & Oracle Cluster Ready > Services idle at about 10% sys due to the huge number of monitoring > scripts that kept firing. This was on a 12 - 16 CPU 25k domain. A
Monitoring scripts and mmap users ... URGH :( That runs into procfs' notorious keenness on locking the address spaces of inspected processes. Even as much as an "ls -l /proc/<PID>/" is acquiring address space locks on that process, and I can see how/why this leads to CPU spikes when you have an application that heavily uses mmap()/munmap(). One could say, if you want this workload to perform well, trust it to perform well and restrain the urge to watch it all the time ... > quite similar configuration on T2000's had negligible overhead. > Lesson learned: cross-calls (and thread migrations, and ...) are much > cheaper on systems with lower latency between CPUs. And quantum theory tells us: If you hadn't looked, that cat might still be living happily ever after ... /proc isn't for free. FrankH. > > -- > Mike Gerdts > http://mgerdts.blogspot.com/ > _______________________________________________ > zfs-discuss mailing list > zfs-discuss@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/zfs-discuss > _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
