Here are few quick notes of what I just went through trying to resolve heavy CPU usage by the kswapd process. Hopefully these can help out any others fighting similar issues:
I have a current RH 7.0 box running kernel 2.2.19. This box was to be replaced by a RH 7.2 box. I built and patched the new server running RH 7.2 all the way to kernel 2.4.9 kernel. I noticed that even with very little running on the box (just starting gnome would do this), CPU utilization would go quite high (consistently stay above 85%). The biggest hog of the CPU would be the kswapd process. I poked around on the web and found out that there is a possible bug in the 2.4.x kernel. Not being a kernel hacker (actually I am somewhat of a newbie to Linux), I did not understand the full details of the bug but it had something to do with Linux making a change somewhere that was resulting in lots of looping somewhere in kswapd (I probably just mangled reality here, but this is what the description of the bug appeared to me). The new server could not be put into production the way it was, since in production it would be running Cyrus imapd, twig, apache + ssl, cvsupd, and Novell's eDirectory for Linux. I decided to try out the 2.4.17 kernel from RedHat's rawhide site to see if fixed the problem. The first issue in trying to install the kernel sources for the 2.4.17 rawhide kernel were the dependencies the kernel source RPM had. I ended up upgrading a bunch of other RPMs to versions from RawHide to be able to get the 2.4.17 kernel source RPM to install. Once all was said and done, I compiled the new kernel, installed, and rebooted. The machine would panic as soon as it launched init (some message about the kernel dereferencing a NULL pointer). I was pretty sure this could not be a bug in the kernel sources (I was hoping RedHat would not put sources with a bug like that on RawHide). I remembered having to upgrade the gcc rpm to version 3 in order to get the kernel sources to install. Knowing RedHat's bad habit of going with beta versions of gcc and glib stuff in the past, I checked out the gcc web site and found that version 3 was NOT recommended for compiling the kernel. Since the 2.4.17 kernel sources were already installed, I figured the gcc 3.x RPM could be back rev'ed to whatever latest 2.x version I could find. I installed gcc-2.96-98 from the RedHat RPM, re-compiled and installed the 2.4.17-01 kernel and rebooted. The machine works great! The heavy CPU usage caused by kswapd is gone and everything seems to be working fine. The only problem I have now is gnome refuses to run (I probably broke a dependency somewhere during the upgrade of various and sundry RPMs in order to get the 2.4.17-01 kernel sources RPM to install). It appears that the heavy CPU usage by kswapd bug introduced in the 2.4 kernel is finally resolved in the 2.4.17-01 kernel available on RedHat's Rawhide site. At this point I just need to figure out how to get gnome running again, but this is not a show stopper as far as going ahead with various types of software installed on this new server. --Moby _______________________________________________ Redhat-list mailing list [EMAIL PROTECTED] https://listman.redhat.com/mailman/listinfo/redhat-list
