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Date: Tue, 16 Jan 2007 12:47:16 -0600
From: Brian Ford <Brian DOT Ford AT FlightSafety DOT com>
Reply-To: cygwin AT cygwin DOT com
To: cygwin AT cygwin DOT com
Subject: Re: Snapshot speed on managing files
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On Sat, 13 Jan 2007, Corinna Vinschen wrote:
> On Jan 12 10:34, Brian Ford wrote:
> > On Fri, 12 Jan 2007, Corinna Vinschen wrote:
> > > Current CVS contains a change which is probably the cause for that.
> > > Before deleting a file, the file is moved to the recycle bin.
> >
> > Couldn't we make this conditional only if a "regular" delete fails because
> > the file is in use?  Would it then only penalize deletes of open files?
> >
> > (Incidentally, I've noticed this as well.)

Ok, I only noticed this anecdotally, not scientifically.  See below...

> Ok, next thing is taking the time with the current implementation
> which always moves the file to the bin:
>
>   $ ./deltest.sh
>   Creating files... Ok.
>   Deleting files ...
>   real    0m2.546s
>   user    0m0.233s
>   sys     0m0.578s

With this test case, I'm in your league:

$ ./deltest.sh
Creating files... Ok.
Deleting files ...
real    0m2.828s
user    0m0.296s
sys     0m1.531s

I'm also running "VirusScan Enterprise 8.0.0 On Access Scanner
Enabled" (corporate policy).

With On Access Scan disabled, I can reproduce the OP's result:

$ ./deltest.sh
Creating files... Ok.
Deleting files ...
real    1m45.333s
user    0m0.093s
sys     0m1.359s

A quick look via Filemon doesn't show where the time is going.  But since
I don't regularly run this way, I'm not that interested in pursuing this
further.

I regularly delete 100,000 files at a time under 1.5.18, and the rm return
is rather snappy.  About two weeks ago I was cleaning space of my drive
under a then current CVS build with On Access Scan enabled (before my 64k
I/O change, although I don't think that's relevant), and deleting a few
thousand files was very slow comparatively.  So, I presumed I had seen the
problem.

Since I can't duplicate this observation now, I'm sorry for the wasted
effort.

-- 
Brian Ford
Lead Realtime Software Engineer
VITAL - Visual Simulation Systems
FlightSafety International
the best safety device in any aircraft is a well-trained crew...



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