RE: Cygwin on Win10 much slower than Win7

["Nellis, Kenneth" <Kenneth dot Nellis at conduent dot com>]

From: Stephen John Smoogen
> Sent: Thursday, November 2, 2017 12:49
> To: cygwin@cygwin.com
> Subject: Re: Cygwin on Win10 much slower than Win7
> 
> On 2 November 2017 at 12:44, Nellis, Kenneth <Kenneth.Nellis@conduent.com>
> wrote:
> > From: cyg Simple
> >> On 11/2/2017 9:36 AM, Erik Bray wrote:
> >> > On Wed, Nov 1, 2017 at 3:50 PM, Nellis, Kenneth wrote:
> >> >> Since migrating from a Windows 7 laptop to one with Windows 10,
> >> >> I've noticed a significant speed decrease in opening a mintty/bash
> >> >> window from about 0.5s to 3.5s.
> >> >>
> >> >> I've narrowed it down to two bottlenecks in .bash_profile:
> >> >> to "cygpath" and "source".
> >> >>
> >> >> Each invocation of cygpath on Win10 takes about 0.12s while on
> >> >> Win7 takes only 0.016s. Both are running 64-bit Cygwin 2.9.0, and
> >> >> cygpath version 2.9.0.
> >> >>
> >> >> The files being sourced are the same, but for example, one file,
> >> >> .bash_aliases, only contains alias statements and a few variable
> >> >> assignments. On Win7, "time" says it takes 0.000s, but on Win10 it
> >> >> takes 0.023s.
> >> >>
> >> >> The Win7 CPU is "i7-4600M @ 2.90 GHz 2.90 GHz" while the
> >> >> Win10 CPU is "i7-6600U @ 2.60 GHz 2.81 GHz". I can't imagine this
> >> >> difference accounts for a 10x speed difference. Also the
> >> >> Win10 machine has an SSD compared to the Win7 machine's SCSI hard
> >> >> disk, which would favor the Win10 machine.
> >> >>
> >> >> I was wondering if anyone else noticed such a thing or could
> >> >> account for this speed difference. Can I simply blame Windows 10?
> >> >
> >> > There could be a real issue here, but for what it's worth I haven't
> >> > noticed such extreme slowdown.  But I don't have a Windows 7
> >> > machine to compare to.  I upgrade the one I'm on now from Windows 7
> >> > to Windows
> >> > 10 over a year ago, so if there ever was a difference maybe I just
> >> > got use to it and didn't notice.
> >> >
> >>
> >> Maybe a network drive connection timeout issue.  Are all of the
> >> drives that were mapped in Win7 still reachable in Win10?
> >>
> >> > I don't recall any major issues when I first upgraded either though
> >> > ¯\_(ツ)_/¯
> >> >
> >>
> >> I don't recall any either.
> >>
> >> --
> >> cyg Simple
> >
> > Yes, I dismounted all but one and same network drive on both machines,
> > and got the same results. The (faster) Win7 machine's network drive is
> > connected over WiFi while the (slower) Win10 machine over Gbit
> > Ethernet, which would seem to favor the slower machine. I hadn't
> > mentioned that the timing tests were all performed on my internal C:
> > drives, so don't think that network drives would be a factor.
> 
> One thing that might also help is how to duplicate what you are testing.
> Even without having network drives etc it could be useful for people to
> see if they are seeing speed differences or if there is something else.

I first noticed the problem with cygpath:
On Win 7:

$ time cygpath abc
abc

real    0m0.016s
user    0m0.000s
sys     0m0.015s
$

On Win 10:

$ time cygpath abc
abc

real    0m0.105s
user    0m0.000s
sys     0m0.062s
$

--Ken Nellis

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