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Re: Performance optimization in av::fixup - use buffered IO, not mapped file
On Dec 12 14:19, Christopher Faylor wrote:
> 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?
No. /bin isn't the problem. Running self-built executables is. If you
have a build system which runs self-built executables as part of the
build process (xgcc), you'd end up with a very slow build, apparently.
Idle musing: It would be interesting to know if building and testing a
gcc toolchain would run much faster if we disable the automatic
spare-file creation in lseek/write.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Project Co-Leader cygwin AT cygwin DOT com
Red Hat
- References:
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file
- Re: Performance optimization in av::fixup - use buffered IO, not mapped file