[Bug symtab/11198] New: Performance problem in find_minsym_and_objfile

[Bug symtab/11198] New: Performance problem in find_minsym_and_objfile

[andre dot poenitz at nokia dot com]

Each time I step the first time into code belonging to some library like QtCore
or QtGui, gdb goes to 100% CPU for 10-20 seconds. That time is spent almost
entirely in find_minsym_and_objfile (char *name, struct objfile **objfile_p) in
glibc-tdep.c. The change below removes the delay and does not seem to have ill
side-effects for me.

--- glibc-tdep.c.orig   2010-01-20 16:00:22.000000000 +0100
+++ glibc-tdep.c        2010-01-20 17:04:41.000000000 +0100
@@ -41,15 +41,12 @@
   ALL_OBJFILES (objfile)
     {
         struct minimal_symbol *msym;
-      ALL_OBJFILE_MSYMBOLS (objfile, msym)
-       {
-         if (SYMBOL_LINKAGE_NAME (msym)
-             && strcmp (SYMBOL_LINKAGE_NAME (msym), name) == 0)
-           {
+        msym = lookup_minimal_symbol (name, NULL, objfile);
+        if ( msym ) 
+         {
              *objfile_p = objfile;
              return msym;
-           }
-       }
+         }
     }

-- 
           Summary: Performance problem in find_minsym_and_objfile
           Product: gdb
           Version: 7.0
            Status: UNCONFIRMED
          Severity: normal
          Priority: P2
         Component: symtab
        AssignedTo: unassigned at sourceware dot org
        ReportedBy: andre dot poenitz at nokia dot com
                CC: gdb-prs at sourceware dot org
 GCC build triplet: i486-linux-gnu
  GCC host triplet: i486-linux-gnu
GCC target triplet: i486-linux-gnu


http://sourceware.org/bugzilla/show_bug.cgi?id=11198

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug symtab/11198] Performance problem in find_minsym_and_objfile

[tromey at redhat dot com]

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
                 CC|                            |tromey at redhat dot com


http://sourceware.org/bugzilla/show_bug.cgi?id=11198

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug symtab/11198] Performance problem in find_minsym_and_objfile

[tromey at redhat dot com]

------- Additional Comments From tromey at redhat dot com  2010-01-20 19:00 -------
Created an attachment (id=4543)
 --> (http://sourceware.org/bugzilla/attachment.cgi?id=4543&action=view)
proposed patch

Please try this patch.
If it works for you, I will check it in.
Thanks.

-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=11198

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug symtab/11198] Performance problem in find_minsym_and_objfile

[andre dot poenitz at nokia dot com]

------- Additional Comments From andre dot poenitz at nokia dot com  2010-01-21 14:45 -------
Yes, it solves the performance problem. 

Time for the initial step into  libQtCore.so is down to 0.4 seconds from 10.2
seconds, both "real" time averaged over four "warm" runs.


-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=11198

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug symtab/11198] Performance problem in find_minsym_and_objfile

[cvs-commit at gcc dot gnu dot org]

------- Additional Comments From cvs-commit at gcc dot gnu dot org  2010-01-21 17:12 -------
Subject: Bug 11198

CVSROOT:	/cvs/src
Module name:	src
Changes by:	tromey@sourceware.org	2010-01-21 17:12:19

Modified files:
	gdb            : ChangeLog minsyms.c symtab.h glibc-tdep.c 

Log message:
	PR symtab/11198:
	* symtab.h (lookup_minimal_symbol_and_objfile): Declare.
	* minsyms.c (lookup_minimal_symbol_and_objfile): New function.
	* glibc-tdep.c (find_minsym_and_objfile): Remove.
	(glibc_skip_solib_resolver): Use
	lookup_minimal_symbol_and_objfile.

Patches:
http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/gdb/ChangeLog.diff?cvsroot=src&r1=1.11284&r2=1.11285
http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/gdb/minsyms.c.diff?cvsroot=src&r1=1.70&r2=1.71
http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/gdb/symtab.h.diff?cvsroot=src&r1=1.144&r2=1.145
http://sources.redhat.com/cgi-bin/cvsweb.cgi/src/gdb/glibc-tdep.c.diff?cvsroot=src&r1=1.12&r2=1.13



-- 


http://sourceware.org/bugzilla/show_bug.cgi?id=11198

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.

[Bug symtab/11198] Performance problem in find_minsym_and_objfile

[tromey at redhat dot com]

------- Additional Comments From tromey at redhat dot com  2010-01-21 17:15 -------
Thanks for trying this.
I've checked in the fix.

-- 
           What    |Removed                     |Added
----------------------------------------------------------------------------
             Status|UNCONFIRMED                 |RESOLVED
         Resolution|                            |FIXED


http://sourceware.org/bugzilla/show_bug.cgi?id=11198

------- You are receiving this mail because: -------
You are on the CC list for the bug, or are watching someone who is.