From: Corinna Vinschen <corinna-cygwin@cygwin.com>
To: cygwin@cygwin.com
Subject: Re: calloc speed difference
Date: Fri, 12 Jan 2018 20:41:00 -0000 [thread overview]
Message-ID: <20180112204149.GF24623@calimero.vinschen.de> (raw)
In-Reply-To: <b7ab3fe3-fa81-432d-33ad-9c0d7948b044@gmail.com>
[-- Attachment #1: Type: text/plain, Size: 1760 bytes --]
On Jan 12 14:59, cyg Simple wrote:
> On 1/12/2018 9:33 AM, Corinna Vinschen wrote:
> > On Jan 12 15:06, Christian Franke wrote:
> >> Timing [cm]alloc() calls without actually using the allocated memory might
> >> produce misleading results due to lazy page allocation and/or zero-filling.
> >>
> >> MinGW binaries use calloc() from msvcrt.dll. This calloc() does not call
> >> malloc() and then memset(). It directly calls:
> >>
> >> mem = HeapAlloc(_crtheap, HEAP_ZERO_MEMORY, size);
> >>
> >> which possibly only reserves allocate-and-zero-fill-on-demand pages for
> >> later.
> >>
> >> Cygwin's calloc() is different.
> >
> > But then again, Cygwin's malloc *is* slow, particulary in
> > memory-demanding multi-threaded scenarios since that serializes all
> > malloc/free calls.
> >
> > The memory handling within Cygwin is tricky. Attempts to replace good
> > old dlmalloc with a fresher jemalloc or ptmalloc failed, but that only
> > means the developer (i.e., me, in case of ptmalloc) was too lazy...
> > busy! I mean busy... to pull this through.
> >
> > Having said that, if somebody would like to take a stab at replacing
> > dlmalloc with something leaner, I would be very happy and assist as
> > much as I can.
>
> Corina, how reliable is the Cygwin time function on a non-Cygwin
> executable? Isn't this a comparison of apples to oranges?
I wasn't comparing, in fact. I was just saying that Cygwin's malloc
is slow, partially because dlmalloc is not the fastest one, partially
due to the serialization overhead in multithreading scenarios.
Corinna
--
Corinna Vinschen Please, send mails regarding Cygwin to
Cygwin Maintainer cygwin AT cygwin DOT com
Red Hat
[-- Attachment #2: signature.asc --]
[-- Type: application/pgp-signature, Size: 833 bytes --]
next prev parent reply other threads:[~2018-01-12 20:41 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-01-12 7:19 Lee
2018-01-12 8:38 ` Eliot Moss
2018-01-12 9:07 ` Marco Atzeri
2018-01-12 10:52 ` Lee
2018-01-21 11:01 ` Marco Atzeri
2018-01-12 14:05 ` Christian Franke
2018-01-12 14:33 ` Corinna Vinschen
2018-01-12 19:59 ` cyg Simple
2018-01-12 20:07 ` cyg Simple
2018-01-12 20:41 ` Corinna Vinschen [this message]
2018-01-12 22:34 ` cyg Simple
2018-01-13 10:48 ` Lee
2018-01-13 10:04 ` Lee
2018-01-12 22:00 ` Eliot Moss
2018-01-13 8:35 ` Lee
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20180112204149.GF24623@calimero.vinschen.de \
--to=corinna-cygwin@cygwin.com \
--cc=cygwin@cygwin.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).