Messages in this thread | | | From | "Peter T. Breuer" <> | Subject | Re: [RFC] mount flag "direct" | Date | Tue, 3 Sep 2002 19:30:18 +0200 (MET DST) |
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"A month of sundays ago David Lang wrote:" > Peter, the thing that you seem to be missing is that direct mode only > works for writes, it doesn't force a filesystem to go to the hardware for > reads.
Yes it does. I've checked! Well, at least I've checked that writing then reading causes the reads to get to the device driver. I haven't checked what reading twice does.
If it doesn't cause the data to be read twice, then it ought to, and I'll fix it (given half a clue as extra pay ..:-)
> for many filesystems you cannot turn off their internal caching of data > (metadata for some, all data for others)
Well, let's take things one at a time. Put in a VFS mechanism and then convert some FSs to use it.
> so to implement what you are after you will have to modify the filesystem > to not cache anything, since you aren't going to do this for every
Yes.
> filesystem you end up only haivng this option on the one(s) that you > modify.
I intend to make the generic mechanism attractive.
> if you have a single (or even just a few) filesystems that have this > option you may as well include the locking/syncing software in them rather > then modifying the VFS layer.
Why? Are you advocating a particular approach? Yes, I agree that that is a possible way to go - but I will want the extra VFS ops anyway, and will want to modify the particular fs to use them, no?
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