cygwin/x symantec antivirus conflict
Sun Oct 10 13:40:00 GMT 2004
Christopher Faylor wrote:
> <>On Wed, Oct 06, 2004 at 10:36:22PM -0400, Philip Gladstone wrote:
>>The slowness that I see with Symantec Antivirus is due to the 'select'
>>emulation in cygwin. Whenever XWin.exe does a select (which is nearly
>>all the time), the select emulation creates a new thread, creates a new
>>TCP socket and then connects to it. I suspect that the Symantec firewall
>>is getting in the picture here and making this a very slow operation.
>Cygwin should not be actually creating threads in this scenario. It
>should be reusing thread from a thread pool.
>If there are a lot of sockets being waited on (which doesn't seem to
>be the case here) then the pool could be exhausted and new threads could
>be created. If that was the issue then we could bump up the size of
>the thread pool.
It doesn't seem to the be the cost of creating the thread, but creating
A simple test program (running in a pure windows environment with
norton) shows that it takes 8-10ms to create a socket.It only takes 30us
to send a udp packet from one socket to another. [This is on a fairly
old and tired machine -- 1.4GHz Athlon --, however I would expect the
ratio to be valid] You could argue that this is a huge problem with
symantec, but I'm not sure that would be helpful!!!!!!!
The select emulation (as I recall) creates 2 TCP Sockets and then
connects from one to the other. This takes around 20ms on my system --
thus limiting me to performing 50 selects per second.
You can find the test program (needs visual studio to build) at
http://pond.gladstonefamily.net/udpself.zip The zip file does contain a
prebuilt exe if you are brave.
* Check out the live pondcam at http://pond.gladstonefamily.net
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