Fedora Linux Rawhide kernel performance is extremely poor due to too many debug options

Fedora Linux Rawhide kernel performance is extremely poor due to too many debug options

Fedora Linux Rawhide kernel performance is extremely poor due to too many debug options.

Fedora Linux provides a number of debugging options during its “Rawhide” development phase to diagnose problems during testing.

But Richard Jones, a Linux developer at Red Hat, found that these debug options cost a lot of performance, making the Fedora Rawhide kernel incredibly slow.

The current Fedora Rawhide kernel is too slow to run libguestfs tests with Koji builds.

They run in a qemu VM, running the Rawhide kernel, emulated using software virtualization (TCG). But now it times out frequently because these kernel debugging options are just too slow.

Richard Jones then examines the performance cost of various debugging options used by the Rawhide kernel.

It was found that the Fedora Rawhide kernel with all debug options increased the test case runtime by 143%, from 12.3 seconds without debug options to over 30 seconds.

According to foreign media Phoronix , the debugging options that currently have the greatest impact on Fedora Rawhide kernel performance include:

• PROVE_LOCKING
• LOCK_STAT
• DEBUG_WW_MUTEX_SLOWPATH
• DEBUG_KMEMLEAK
• DEBUG_LOCK_ALLOC
• PAGE_TABLE_CHECK_ENFORCED

Richard Jones outlines his test results on the Fedora kernel mailing list and has an extensive discussion of debugging options for the Fedora Rawhide kernel.

He wants to check whether these kernel debugging options are degraded upstream, causing the performance of the Fedora Rawhide kernel to plummet, and is also considering whether to drop some expensive debugging options.