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Date: Thu, 11 Apr 2002 17:19:00 -0000
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To: gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org, leitner@fefe.de,
  nobody@gcc.gnu.org
From: rth@gcc.gnu.org
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  leitner@fefe.de, nobody@gcc.gnu.org, gcc-gnats@gcc.gnu.org
Subject: Re: libstdc++/4150: catastrophic performance decrease in C++ code
X-SW-Source: 2002-04/txt/msg00637.txt.bz2
List-Id: <gcc-prs.sourceware.org>

Synopsis: catastrophic performance decrease in C++ code

State-Changed-From-To: open->analyzed
State-Changed-By: rth
State-Changed-When: Thu Apr 11 17:19:06 2002
State-Changed-Why:
    Still present in 3.1.  We're seeking unnecessarily, even after
    adding a sync_with_stdio(false) to the source (which I now attach
    to the PR).  Strace shows
    
    _llseek(4, 8192, {8192}, SEEK_SET)      = 0
    read(4, "AOL (Traffic-Server/1.1.6 [1])\""..., 8192) = 8192
    _llseek(4, 8192, {8192}, SEEK_SET)      = 0
    _llseek(4, 16384, {16384}, SEEK_SET)    = 0
    read(4, "cur=0&skip=10\" \"Mozilla/4.0 (c"..., 8192) = 8192
    _llseek(4, 16384, {16384}, SEEK_SET)    = 0
    
    which indeed agrees with what basic_filebuf<>::underflow is
    doing.  To my mind this is appalling waste.  Surely this is
    not necessary when sync is off?

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=4150