[CentOS-virt] Xen performance (very slow) problem with 4GB of RAM.
olson at irinim.net
Sun Feb 3 17:23:10 UTC 2008
I just took the x64 CentOS 5.1/Xen system I've been working on and
upgraded from 2GB to 4GB of memory. Fresh minimal install of the OS (to
remove some 3.2 stuff I had done trying to make PCI passthrough work).
No special options, just a flat out default install.
Dom0 is incredibly slow, I haven't tried DomU's yet to see if they are
affected. X in particular is impressively slow (you can watch the screen
be filled in one little block at a time, with several seconds between
blocks) but it's not just video apps, it takes a considerable amount of
time for the Xend daemon to start during boot. Before worrying about it
I updated everything, same problem. Nothing interesting looking in dmesg
I tried out the vanilla kernel and it booted/ran well, no sign of the
Next, I tried Dom0 limited to 1.5GB (kernel /xen.gz-2.6.18-53.1.6.el5
dom0_mem=1536M), and it performed well.
This workaround is probably adequate for me, I haven't found what the
boundary conditions are on the problem and I haven't tested DomU
performance yet. A Google and BugTracker search didn't turn this problem
described elsewhere, is this known or is this something unique to me?
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