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[Bug libfortran/21820] Really, really, horrible IO performance
- From: "sgk at troutmask dot apl dot washington dot edu" <gcc-bugzilla at gcc dot gnu dot org>
- To: gcc-bugs at gcc dot gnu dot org
- Date: 31 May 2005 16:48:37 -0000
- Subject: [Bug libfortran/21820] Really, really, horrible IO performance
- References: <20050530143227.21820.kargl@gcc.gnu.org>
- Reply-to: gcc-bugzilla at gcc dot gnu dot org
------- Additional Comments From sgk at troutmask dot apl dot washington dot edu 2005-05-31 16:48 -------
Subject: Re: Really, really, horrible IO performance
On Tue, May 31, 2005 at 07:38:41AM -0000, fxcoudert at gcc dot gnu dot org wrote:
> First thing: I can reproduce the timings differences on my i386-linux,
> with ext3 filesystem.
>
> Second thing: Steve, your patch truncates files, which is not correct!
> Given the following modified testcase
Yes, I know. See http://gcc.gnu.org/ml/fortran/2005-05/msg00420.html.
Note, I played with various combination of mmap flags with
no notice difference in performance. Also, I run FreeBSD with
debugging kernel features, which causes a significant increase
over non-debugging kernels. I've observed that if the file
does not exist, the execution time is on order of 0.01 s. With
a debugging kernel, I see execution times on the order of 70 s.
With a non-debugging kernel, I see times on the order of 1 s.
--
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=21820