This is the mail archive of the cygwin mailing list for the Cygwin project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

Re: cygwin copy problems usb 2.0


On Thu, 3 Aug 2006, Corinna Vinschen wrote:

> On Aug  3 01:54, Eric Blake wrote:
> > > >I'm really seeing the non-optimized cygwin cp behaviour causing bad
> > > >reputation, which could be easily patched and maybe even accepted
> > > >upstream. Who knows. Eric what do think? Would it be worthful to think
> > > >about?
> >
> > I don't really want to maintain a Windows API patch, and doubt that
>
> Good.
>
> > it would be accepted upstream.  Now if there were something more
> > POSIX-y that we could do to speed things up, such as posix_fadvise,
>
> posix_fadvise can't be implemented nicely, AFAICS.  The POSIX semantics
> require an already opened file and the advice is given for an offset and
> a length.  The Windows semantics only allow to give the advice for the
> whole file, and only switching between FILE_SEQUENTIAL_ONLY or "normal",
> using ZwSetInformationFile.  By re-opening the file using ZwOpenFile it
> would also be possible to toggle the FILE_RANDOM_ACCESS flag.  Still,
> it's always for the whole file, not for an area giving offset and length.

Theoretically, it's possible to implement posix_fadvise only for offset=0
and length=<length-of-file>, and have it fail with EINVAL otherwise...
While technically not POSIX-compliant, it would still allow for better
implementation of things like copy...
	Igor
-- 
				http://cs.nyu.edu/~pechtcha/
      |\      _,,,---,,_	    pechtcha@cs.nyu.edu | igor@watson.ibm.com
ZZZzz /,`.-'`'    -.  ;-;;,_		Igor Peshansky, Ph.D. (name changed!)
     |,4-  ) )-,_. ,\ (  `'-'		old name: Igor Pechtchanski
    '---''(_/--'  `-'\_) fL	a.k.a JaguaR-R-R-r-r-r-.-.-.  Meow!

"Las! je suis sot... -Mais non, tu ne l'es pas, puisque tu t'en rends compte."
"But no -- you are no fool; you call yourself a fool, there's proof enough in
that!" -- Rostand, "Cyrano de Bergerac"

--
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple
Problem reports:       http://cygwin.com/problems.html
Documentation:         http://cygwin.com/docs.html
FAQ:                   http://cygwin.com/faq/


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]