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SubjectRe: Special Kernel Modification
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bodnar42@phalynx.dhs.org said:
> > Mounting it synchronous will disable caching in the VM.
> Who told
> you that? Synchronous mounting turns off write buffering. Even with
> "-o sync" writes will still end up in the page cache, they'll just be
> commited immediately.

Ummm, how about O_DIRECT instead of O_SYNC (or maybe as well, my googling
hasn't been clear on whether O_DIRECT bypasses the cache on writes as well)?

All IO bypasses the virtual machine cache, so there's no multiple caching.

> Er, it will be shared in the host's context, but each VM will still
> have their own copy in the page cache. This is no better than a
> COW'ed block device

Nope. You O_DIRECT here as well.

Jeff

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