Messages in this thread | | | Date | Sat, 6 Dec 2003 01:25:22 +0200 (MET DST) | From | Szakacsits Szabolcs <> | Subject | Re: Is there a "make hole" (truncate in middle) syscall? |
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On Fri, 5 Dec 2003, [iso-8859-1] M?ns Rullg?rd wrote: > Szakacsits Szabolcs <szaka@sienet.hu> writes: > > >> What are the downsides of holes? [...] is there a performance penalty to > >> having a file with 1000 4k holes in it, etc...) > > > > Depends what you do, what fs you use. Using XFS XFS_IOC_GETBMAPX you might > > get a huge improvement, see e.g. some numbers, > > > > http://marc.theaimsgroup.com/?l=reiserfs&m=105827549109079&w=2 > > > > The problem is, 0 general purpose (like cp, tar, cat, etc) util supports > > it, you have to code your app accordingly. > > I found this paragraph in the man page of GNU cp: > > --sparse=WHEN
I meant using XFS_IOC_GETBMAPX. tar and cp sparse support is extremely inefficient (Helge also misunderstood what I meant). Only XFS provides support doing it the fastest way, without reading and analysing the data.
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