This is the mail archive of the
libstdc++@gcc.gnu.org
mailing list for the libstdc++ project.
Re: Killing two birds with a one-line configuration change
- From: Richard Henderson <rth at redhat dot com>
- To: rittle at labs dot mot dot com
- Cc: libstdc++ at gcc dot gnu dot org
- Date: Thu, 11 Apr 2002 19:02:59 -0700
- Subject: Re: Killing two birds with a one-line configuration change
- References: <200204120145.g3C1j9c82731@latour.rsch.comm.mot.com>
On Thu, Apr 11, 2002 at 08:45:09PM -0500, Loren James Rittle wrote:
> If someone on a Linux platform could *please* just try my suggested fix ...
With your suggested fix, runtime is 13.74 seconds instead of 14.03.
The lseeks are still present in the strace output.
I really didn't expect your patch to help, because _GLIBCPP_AVOID_FSEEK
merely emulates lseek with displacement 1 with getc/ungetc. However,
my main point is that we shouln't have any lseeks whatsoever!
> [1] libstdc++-v3 adheres to the standard in ways that affect
> performance that libstdc++-v2, as shipped with gcc 2.95.2, did not.
What ways are these?
I should add that if not affecting the read cursor is for some
unexplained reason absolutely required by the standard, then we
should be using pread instead of lseek+read+lseek.
r~