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Subject: Re: slow handling of large sets of files?
From: Ken Sheldon <Ken_Sheldon AT ACM DOT org>
To: cygwin AT cygwin DOT com
Content-Type: text/plain
Date: Tue, 01 Feb 2005 13:28:50 -0600
Message-Id: <1107286130.3063.65.camel@slb163188094105.sugar-land.nam.slb.com>
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I too have been seeing a problem with very slow file access in large
directories.

Specifically,

On a Cygwin/Win2k box, I have a mirror of an FTP site.  The site has 2.5
million files spread between 100 directories.  
(20,000 - 30,000 files per directory)  I have previously run this number
of files in an NT4 NTFS filesystem without significant performance
problems.

In this site, operations like these are __VERY__ slow.
ls ${some_dir}
ls ${some_dir}/${some_path}
cp ${some_file} ${some_path}
cp -R ${some_path_with _only_a_few_files} ${some_path}


If I look at the performance monitor, I can see a queue depth of 1-2 and
300-500 disk reads per second.  (That's real.  It's a fast array)  The
reads appear to be single-block reads, as the throughput during these
events is 1.5 - 3MB/sec.

I am beginning to think the disk activity relates to NTFS permission
checking, which can be complex under Win2k.

I don't know how to debug or tune this.

Any ideas?


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