Messages in this thread | | | Subject | Re: Is there a "make hole" (truncate in middle) syscall? | From | Vladimir Saveliev <> | Date | Fri, 12 Dec 2003 16:28:18 +0300 |
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Hi
On Fri, 2003-12-12 at 15:55, Jörn Engel wrote: > On Thu, 11 December 2003 14:32:12 -0600, Rob Landley wrote: > > On Thursday 11 December 2003 13:48, Jörn Engel wrote: > > > > > > If you really do it, please don't add a syscall for it. Simply check > > > each written page if it is completely filled with zero. (This will be > > > a very quick check for most pages, as they will contain something > > > nonzero in the first couple of words) > > > > Cache poisoning, streaming writes to large RAID arrays... There are about 8 > > zllion reasons not to do this. Really. (It defeats the whole purpose of > > DMA, doesn't it?) >
Sorry, but doesn't truncate do almost exactly what "make hole" is supposed to do?
> Yes, the obvious and stupid implementation has a ton of problems. > Most likely the right approach is some sort of background deamon > (garbage collector, defragmenter, journald, whatever you may call it) > that does exacly this even after the fact for the last unchecked > writes. Asyncronous under load, possibly even synchronous when almost > idle. > > A stupid implementation would still help for some workload (few, while > hurting many) and already get the code tested, so even a stupid > implementation helps. > > Jörn
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