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From: "John Pollock" <jpollock AT curl DOT com>
To: <cygwin AT sourceware DOT cygnus DOT com>
Subject: cygwin's filesystem activity
Date: Fri, 17 Nov 2000 13:34:17 -0500
Message-ID: <NEBBJPGNBOKKDAEIIMIKAEMACCAA.jpollock@curl.com>
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While i was trying to debug some of the -j2 hangs using cygwin-1.1.5-7
(knowing that Chris has already reported he knows what the problem is and is
working on it), i started using filemon (a tool for monitoring read/writes
to the filesystem) to see what cygwin was doing at the moment of the hang,
just for my own edification.  I filtered out all noise except traffic
generated by bash or make.  There was still a great deal of noise, but then
i noticed a strange and repetitive set of entries: buffer overflows coming
from IRP_MJ_QUERY_VOLUME_INFORMATION and IRP_MJ_QUERY_INFORMATION (and only
these two calls, i might add; no other kinds of calls generated this
overflow).  These messages were generated by both bash and make activity, as
seen by the examples below:

1059	0.00000649	bash.exe	IRP_MJ_QUERY_VOLUME_INFORMATION
C:\cygwin\bin\make.exe	BUFFER OVERFLOW	FileFsVolumeInformation
1060	0.00001067	bash.exe	IRP_MJ_QUERY_INFORMATION	C:\cygwin\bin\make.exe
BUFFER OVERFLOW	FileAllInformation
1456	0.00000568	make.exe	IRP_MJ_QUERY_VOLUME_INFORMATION
C:\cygwin\usr\local\include	BUFFER OVERFLOW	FileFsVolumeInformation
1457	0.00001077	make.exe	IRP_MJ_QUERY_INFORMATION
C:\cygwin\usr\local\include	BUFFER OVERFLOW	FileAllInformation

There is also a pattern of cygwin creating a directory (at least, if
i read the IRP_MJ_CREATE correctly) but then getting an INVALID_DEVICE error
when trying to read it:

1033846	0.00004414	bash.exe	IRP_MJ_CREATE
C:\cygwin\scratch\jpollock\build-installer\socket	SUCCESS	Attributes: N
Options: Open
1033847	0.00000532	bash.exe	IRP_MJ_READ
C:\cygwin\scratch\jpollock\build-installer\socket	INVALID DEVICE REQUEST
Offset: 0 Length: 3

And there's also some interesting attempts by cygwin to check for .exe
versions of some directories:

21409	0.00008309	make.exe	IRP_MJ_CREATE
U:\jpollock\checkouts\curl-installer\gfx\Texture\RCS.exe	SUCCESS	Attributes:
Any Options: Open
21410	0.00110612	make.exe	FASTIO_QUERY_BASIC_INFO
U:\jpollock\checkouts\curl-installer\gfx\Texture\RCS.exe	NO SUCH FILE
Attributes: Error

I was hoping someone could help me understand these calls.

Thanks much!
John


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