Performance optimization in av::fixup - use buffered IO, not mapped file

Christopher Faylor
Wed Dec 12 19:19:00 GMT 2012

On Wed, Dec 12, 2012 at 06:27:33PM +0100, Corinna Vinschen wrote:
>On Dec 12 18:15, Corinna Vinschen wrote:
>> On Dec 12 12:11, Christopher Faylor wrote:
>> > On Wed, Dec 12, 2012 at 12:06:08PM -0500, Ryan Johnson wrote:
>> > >It's painfully reproducible. It takes nearly two hours for a gcc 
>> > >bootstrap compiler to configure the various bits of the next stage. It's 
>> > >the same for emacs unexec (as OP reported).
>> > 
>> > I'd like to see a small controlled test case which demonstrates the
>> > problem.  If the claims here are all true then it should be very easy to
>> > demonstrate without resorting to bootstrapping the compiler.
>> > 
>> > And, given my comment about setup.exe, I suspect that this isn't going
>> > to be as alarming an issue for the normal Cygwin user as it is for
>> > people who, e.g., rebuild their own compilers.
>> Which would speak for adding a "nosparse" mount option.
>...or not.  The problem is not to add the mount option, but to make sure
>people know that option and use it when "cygwin is slow".  This rather
>speaks for making nosparse the default and "sparse" the option, I guess.

Actually, if the assertions here are correct then wouldn't mounting /bin
as "cygexec" also make things better?

(Yes, I know that this screws up mingw binaries like strace and cygcheck)


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