++
AssignedTo: unassigned at gcc dot gnu dot org
ReportedBy: tstarling at wikimedia dot org
GCC build triplet: i486-linux-gnu
GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu
http://gcc.gnu.org/bugzilla/show_bug.cgi?id=45574
--- Comment #2 from tstarling at wikimedia dot org 2010-09-07 10:46 ---
(In reply to comment #1)
> If the problem is in the stdio sync code, then file a glibc PR.
>
I mean the "stdio sync code" as in the code in libstdc++ which synchronises
with glibc, not actual code
--- Comment #4 from tstarling at wikimedia dot org 2010-09-07 17:18 ---
Benchmarking on Solaris indicates that cin.getline() takes only 1us per
iteration there, but I don't think the source code is available, so it's hard
to provide details.
However, I think that a huge spe
--- Comment #8 from tstarling at wikimedia dot org 2010-09-08 01:34 ---
(In reply to comment #5)
> For sure we cannot add virtual functions to basic_streambuf without breaking
> the ABI.
I'm mostly looking for a long-term fix, to improve the speed of libstdc++
application
--- Comment #9 from tstarling at wikimedia dot org 2010-09-08 02:36 ---
Created an attachment (id=21732)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21732&action=view)
10 lines, 500 bytes per line
Test file attached as requested, compressed with gzip. Test code
--- Comment #14 from tstarling at wikimedia dot org 2010-09-09 02:31
---
(In reply to comment #11)
> So? We are not changing glibc here. The C++ library does *not* use buffering
> in
> the synced mode, and it does otherwise, for fstreams in particular. Where do
> y
--- Comment #18 from tstarling at wikimedia dot org 2010-09-09 14:12
---
Created an attachment (id=21752)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21752&action=view)
gprof output
I haven't managed to get libstdc++ to compile with -pg, but compiling the test
--- Comment #19 from tstarling at wikimedia dot org 2010-09-09 14:28
---
(In reply to comment #16)
> The *_unlocked versions are faster a lot actually, at least for the one
> character ops, because no locking is performed and the calls are inlined.
> But the question is whethe
--- Comment #23 from tstarling at wikimedia dot org 2010-09-10 00:17
---
(In reply to comment #21)
> Anyway, not sure which STL getline we are talking about here, because e.g.
> src/istream.cc getline seems to access the stdio buffer directly:
> streamsi
--- Comment #24 from tstarling at wikimedia dot org 2010-09-10 15:25
---
Created an attachment (id=21766)
--> (http://gcc.gnu.org/bugzilla/attachment.cgi?id=21766&action=view)
dynamic_cast<> hack
The attached patch uses a dynamic_cast<> hack to avoid the need
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