Am 22.07.2014 um 22:06 hat Max Reitz geschrieben: > On 21.07.2014 17:52, Eric Blake wrote: > >On 07/19/2014 02:35 PM, Max Reitz wrote: > >>Many qemu-img subcommands only read the source file(s) once. For these > >>use cases, a full write-back cache is unnecessary and mainly clutters > >>host cache memory. Though this is generally no concern as cache memory > >>is freely available and can be scaled by the host OS, it may become a > >>concern with thin provisioning. > >> > >>For these cases, it makes sense to allow users to freely specify the > >>source cache mode (e.g. use no cache at all). > >> > >>This commit adds a new switch (-T) for the qemu-img subcommands check, > >>compare, convert and rebase to specify the cache to be used for source > >>images (the backing file in case of rebase). > >What mnemonic did you have in mind when choosing -T? Or was it just a > >universally available letter for the subcommands you were touching? > > To be honest, I just didn't know what -t stands for. Therefore I > just thought it might be remotely logical if the lower-cased letter > is used for destination and the upper-cased letter for source > caching.
Things might get a bit confusing there, though, because upper-case often means the "other image", i.e. destination or backing file, in other commands (create -F, compare -F, convert -O and -B, rebase -F). Of course, most of them are deprecated, so I wouldn't make that a reason to block this series, but perhaps we should consider using more long options instead of randomly assigning the letters that are still free. Kevin