Messages in this thread | | | From | Daniel Phillips <> | Subject | Re: [ANNOUNCE] Ramback: faster than a speeding bullet | Date | Sat, 15 Mar 2008 13:47:00 -0800 |
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On Saturday 15 March 2008 14:33, Pavel Machek wrote: > On Sat 2008-03-15 12:22:47, Daniel Phillips wrote: > > On Saturday 15 March 2008 06:32, Pavel Machek wrote: > > > On Wed 2008-03-12 22:50:55, Daniel Phillips wrote: > > > > On Wednesday 12 March 2008 23:30, David Newall wrote: > > > > > Daniel Phillips wrote: > > > > > >> Your idea seems predicated on throwing large amounts of RAM at the > > > > > >> problem. What I want to know is this: Is it really 25 times faster than > > > > > >> ext3 with an equally huge buffer cache? > > > > > > > > > > > > Yes. > > > > > > > > > > Well, that sounds convincing. Not. You know this how? > > > > > > > > By measuring it. time untar -xf linux-2.2.26.tar; time sync > > > > > > Thats cheating. Your ramback ignores sync. > > > > > > Just time it against ext3 _without_ doing the sync. That's still more > > > reliable than what you have. > > > > No, that allows ext3 to cheat, because ext3 does not supply any means > > of flushing its cached data to disk in response to loss of line power, > > and then continuing on in a "safe" mode until line power comes back. > > Ok, it seems like "ignore sync/fsync unless on UPS power" is what you > really want? That should be easy enough to implement, either in > kernelor as a LD_PRELOAD hack.
Sure, let's try it and then we will have a race. I would be happy to lose that race, but... let's just see who wins.
> So... untar with sync is fair benchmark against ramback on UPS power > and untar without sync is fair benchmark against ramback on AC power. > > But you did untar with sync against ramback on AC power. > > That's wrong.
It is consistent and correct. You need to supply the missing features that ramback supplies before you have a filesystem-level solution. I really encourage you to try it, then we can compare the two approaches with both of them fully working.
Daniel
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