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    SubjectRe: [PATCH 26/30] ext4: do not send discards as barriers
    On Mon 30-08-10 15:56:43, Jeff Moyer wrote:
    > Jan Kara <> writes:
    > > An update: I've set up an ext4 barrier testing in KVM - run fsstress,
    > > kill KVM at some random moment and check that the filesystem is consistent
    > > (kvm is run in cache=writeback mode to simulate disk cache). About 70 runs
    > But doesn't your "disk cache" survive the "power cycle" of your guest?
    Yes, you're right. Thinking about it now the test setup was wrong because
    it didn't refuse writes to the VM's data partition after the moment I
    killed KVM. Thanks for catching this. I will probably have to use the fault
    injection on the host to disallow writing the device at a certain moment.
    Or does somebody have a better option?
    My setup is that I have a dedicated partition / drive for a filesystem
    which is written to from a guest kernel running under KVM. I have set it up
    using virtio driver with cache=writeback so that the host caches the writes
    in a similar way disk caches them. At some point I just kill the qemu-kvm
    process and at that point I'd like to also throw away data cached by the


    Jan Kara <>
    SUSE Labs, CR

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      Last update: 2010-08-30 22:23    [W:0.028 / U:15.280 seconds]
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