Re: dvd+rw-tools update [6.0, DVD-R DL]
Bill Davidsen <davidsen@tmr.com> wrote:
> My belief is that if O_DIRECT is in the kernel headers it works. I would
> love to have time to test timing of O_DIRECT on (a) disk, (b) partition,
> (c) file on disk, and alignment on minimal vs. page size boundaries.
> Doing O_DIRECT writes of anything avoids buffer pool collisions. To test
> either hack mkisofs to write with O_DIRECT or pipe into Dwriter or
> similar and see the difference in create time of a DVD image. I may
> actually do the hack and enable it when -o is used (and on Linux). If I
> do I'll put up the patch and post a link here. Then Joerg can reject it
> because it makes mkisofs run faster on Linux.
Statements like this one from self called "Linux specialists" are an important
reason why "Linux specialists" constantly disqualify themself :-(
If you take the time you needed to write this for running a test, you would
know that O_DIRECT makes file I/O slower than by using the standard method.
Star needs only 40% of the system CPU time when using O_DIRECT, but slows
down by 30%.
And BTW: You cannot use O_DIRECT on Linux without defining __USE_GNU
but doing this uncovers broken prototypes that prevent compilation.
I used 040000 instead of O_DIRECT for my tests.
Jörg
--
EMail:joerg@schily.isdn.cs.tu-berlin.de (home) Jörg Schilling D-13353 Berlin
js@cs.tu-berlin.de (uni)
schilling@fokus.fraunhofer.de (work) Blog: http://schily.blogspot.com/
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