Description of problem: When using an encrypted filesystem on LVM, whether an encrypted PV or LV, the kernel frequently blocks for long periods of time waiting for I/O. top shows anywhere from 20% to 100% CPU time waiting for I/O. Affected processes freeze for several seconds, up to a minute or more, waiting for even small disk reads/writes. Version-Release number of selected component (if applicable): kernel-2.6.25.6-55.fc9.x86_64 How reproducible: Random Steps to Reproduce: 1. Install Fedora 9 to encrypted PV. 2. Use moderately disk intensive processes such as firefox, thunderbird or liferea. Actual results: Some disk operations take dozens of seconds to complete. Expected results: Disk operations should complete in a reasonable time. Additional info: Issue did not occur with Fedora 8. Help tracking this down would be greatly appreciated.
this is likely another case of the 'firefox fsyncs too much' bug. (it calls fsync every time it updates the history db - ie, each time you view a new page. unfortunatly fsync on ext3 means 'write everything in memory out to disk, not just the data from this process'.
There is commit in 2.6.26 kernel (adding cond_resched()) in dmcrypt code, which should help in this situation. (System still need wait for io to finish, but other running application should be more responsible.)
cond_resched() call is in 2.6.26+ kernels, it should help in some situations. There are still some situations when system will wait for IO - mainly if you have multiple LVs but only one encrypted PV... closing this rahwide, there is already kernel with this patch.