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Date: Sun, 27 Jun 2004 19:43:50 -0400
From: Christopher Faylor <cgf-no-personal-reply-please AT cygwin DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: higher-level IO very slow with cygwin1.dll 5.10 (due to set_flags?)
Message-ID: <20040627234350.GA13744@trixie.casa.cgf.cx>
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On Sun, Jun 27, 2004 at 05:29:50PM -0400, Pierre A. Humblet wrote:
>On Sun, Jun 27, 2004 at 03:42:05PM -0400, Christopher Faylor wrote:
>> On Sat, Jun 26, 2004 at 01:41:45PM -0400, Pierre A. Humblet wrote:
>
>> >Digging deeper, I see there is a function getc_unlocked. Using it
>> >instead of getc improves the speed by a factor 5. 
>> >Now that I know about it, I will redefine getc to getc_unlocked when
>> >porting single threaded applications.
>> >
>> >That issue may be a factor in the legendary slowness of Cygwin.
>> 
>> FWIW, I added some code to this particular locking function to avoid
>> doing any locks if there is only one thread.  I'm generating a snapshot
>> now.  It will be interesting to see if it improves things.  I didn't
>> do any benchmarking.  I just verified that it worked the way I thought
>> it should by looking at strace output.
>
>Here it is, using a slightly modified version of Joseph's program
>http://cygwin.com/ml/cygwin/2004-06/msg00877.html
>
>Your change makes getc work almost as fast a getc_unlocked.
>This is on Win98. Yesterday's results were on WinME, where the
>differences were larger. That hard drive died this morning :(

Sorry to hear that.  I've been going through hard disk problems
myself.

Thanks for verifying that the change worked.

cgf

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