Re: libstdc++/5457: Writing to buffer stream writes each byte using a system write() call.

Re: libstdc++/5457: Writing to buffer stream writes each byte using a system write() call.

[paolo]

Synopsis: Writing to buffer stream writes each byte using a system write() call.

Responsible-Changed-From-To: unassigned->paolo
Responsible-Changed-By: paolo
Responsible-Changed-When: Tue Jan 22 14:01:13 2002
Responsible-Changed-Why:
    Analyzed	
State-Changed-From-To: open->feedback
State-Changed-By: paolo
State-Changed-When: Tue Jan 22 14:01:13 2002
State-Changed-Why:
    Could you please check if your applications benefit from
    calling:
    
      std::ios::sync_with_stdio(false);
    
    before any I/O operation??
    
    Thanks,
    Paolo.
    
    P.S. For some details on this, see, f.i., Josuttis, pp. 682.

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5457

Re: libstdc++/5457: Writing to buffer stream writes each byte using a system write() call.

[paolo]

Synopsis: Writing to buffer stream writes each byte using a system write() call.

State-Changed-From-To: feedback->closed
State-Changed-By: paolo
State-Changed-When: Tue Jan 22 15:53:40 2002
State-Changed-Why:
    Fine. I'm closing this.
    Cheers, Paolo.
    
    P.S. Good catch!

http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5457

Re: libstdc++/5457: Writing to buffer stream writes each byte using a system write() call.

[Edward Maros]

The following reply was made to PR libstdc++/5457; it has been noted by GNATS.

From: Edward Maros <emaros@ligo.caltech.edu>
To: paolo@gcc.gnu.org, gcc-bugs@gcc.gnu.org, gcc-prs@gcc.gnu.org,
        nobody@gcc.gnu.org, gcc-gnats@gcc.gnu.org
Cc:  
Subject: Re: libstdc++/5457: Writing to buffer stream writes each byte using a 
 system write() call.
Date: Tue, 22 Jan 2002 15:28:06 -0800

 paolo@gcc.gnu.org wrote:
 
 > Synopsis: Writing to buffer stream writes each byte using a system write() call.
 >
 > Responsible-Changed-From-To: unassigned->paolo
 > Responsible-Changed-By: paolo
 > Responsible-Changed-When: Tue Jan 22 14:01:13 2002
 > Responsible-Changed-Why:
 >     Analyzed
 > State-Changed-From-To: open->feedback
 > State-Changed-By: paolo
 > State-Changed-When: Tue Jan 22 14:01:13 2002
 > State-Changed-Why:
 >     Could you please check if your applications benefit from
 >     calling:
 >
 >       std::ios::sync_with_stdio(false);
 >
 >     before any I/O operation??
 >
 >     Thanks,
 >     Paolo.
 >
 >     P.S. For some details on this, see, f.i., Josuttis, pp. 682.
 >
 > http://gcc.gnu.org/cgi-bin/gnatsweb.pl?cmd=view%20audit-trail&database=gcc&pr=5457
 
 This does address my issue. Thank you for your help.
 
 Ed
 
 --
 ------
 Edward Maros                            emaros@ligo.caltech.edu
 
 
 

libstdc++/5457: Writing to buffer stream writes each byte using a system write() call.

[emaros]

>Number:         5457
>Category:       libstdc++
>Synopsis:       Writing to buffer stream writes each byte using a system write() call.
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    unassigned
>State:          open
>Class:          pessimizes-code
>Submitter-Id:   net
>Arrival-Date:   Tue Jan 22 13:46:05 PST 2002
>Closed-Date:
>Last-Modified:
>Originator:     emaros@ligo.caltech.edu
>Release:        gcc-3.0.3
>Organization:
>Environment:
RedHat 7.2 Linux/Intel
Reading specs from /ldcg/lib/gcc-lib/i686-pc-linux-gnu/3.0.3/specs
Configured with: ../configure --prefix=/ldcg --with-prefix=/ldcg --enable-long-long
Thread model: single
gcc version 3.0.3
>Description:
When writing to cout, each character is being written via
the system write() call.Ouput of strace:

...
fstat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 7), ...}) = 0
mmap2(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40206000
ioctl(1, TCGETS, {B38400 opost isig icanon echo ...}) = 0
write(1, "H", 1H)                        = 1
write(1, "e", 1e)                        = 1
write(1, "l", 1l)                        = 1
write(1, "l", 1l)                        = 1
write(1, "o", 1o)                        = 1
write(1, " ", 1 )                        = 1
write(1, "W", 1W)                        = 1
write(1, "o", 1o)                        = 1
write(1, "r", 1r)                        = 1
write(1, "l", 1l)                        = 1
write(1, "d", 1d)                        = 1
write(1, "!", 1!)                        = 1
write(1, "\n", 1
)                       = 1
munmap(0x40206000, 4096)                = 0
_exit(0)                                = ?
>How-To-Repeat:
g++ t.cc
strace ./a.out
>Fix:

>Release-Note:
>Audit-Trail:
>Unformatted:
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