emacs-devel
[Top][All Lists]
Advanced
[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

redisplay - very long lines

From: David Reitter
Subject: redisplay - very long lines
Date: Mon, 16 Feb 2009 08:44:23 -0500
The redisplay code seems to be unable to deal efficiently with very long lines, that is, lines that go beyond the currently displayed window.
This was pointed out by a blogger who wanted to abuse Emacs to make a quick change to a binary file. I could reproduce the problem using a 17MB binary file, which loaded and displayed fine initially. I then removed all newlines from the file, upon which redisplay gets unbearably slow (minutes to redisplay once).
Setting truncate-lines makes things faster, but not to the point where one could work.
This is in version 22 and 23. The profiler output (Shark) is below. Would it be possible to add a termination condition in move_it_to to stop after leaving the window vertically or horizontally (with truncate-lines)? Or simply use a large enough threshold? 



        0.0%    99.8%   Emacs   start   
        0.0%    99.8%   Emacs    main   
        0.0%    99.8%   Emacs     Frecursive_edit       
        0.0%    99.8%   Emacs      recursive_edit_1     
        0.0%    99.8%   Emacs       command_loop        
        0.0%    99.8%   Emacs        internal_catch     
        0.0%    99.8%   Emacs         command_loop_2    
        0.0%    99.8%   Emacs          internal_condition_case  
        0.0%    99.8%   Emacs           command_loop_1  
        0.0%    99.8%   Emacs            call3  
        0.0%    99.8%   Emacs             Ffuncall      
        0.0%    99.8%   Emacs              Fcall_interactively  
        0.0%    99.8%   Emacs               apply1      
        0.0%    99.8%   Emacs                Fapply     
        0.0%    99.8%   Emacs                 Ffuncall  
        0.0%    99.8%   Emacs                  funcall_lambda   
        0.0%    99.8%   Emacs                   Fbyte_code      
        0.0%    99.8%   Emacs                    Ffuncall       
        0.0%    99.8%   Emacs                     funcall_lambda        
        0.0%    99.8%   Emacs                      Fbyte_code   
        0.0%    99.8%   Emacs                       Ffuncall    
        0.0%    99.8%   Emacs                        funcall_lambda     
        0.0%    99.8%   Emacs                         Fbyte_code        
        0.0%    99.8%   Emacs                          Ffuncall 
        0.0%    99.8%   Emacs                           Freplace_match  
        0.0%    99.8%   Emacs                            replace_range  
        0.0%    99.8%   Emacs                             signal_after_change   
        0.0%    99.8%   Emacs                              run_hook_with_args   
        0.0%    99.8%   Emacs                               Ffuncall    
        0.0%    99.8%   Emacs                                Fgarbage_collect   
        0.0%    99.8%   Emacs                                 
truncate_undo_list        
        0.0%    99.8%   Emacs                                  call1    
        0.0%    99.8%   Emacs                                   Ffuncall        
        0.0%    99.8%   Emacs                                    funcall_lambda 
        0.0%    99.8%   Emacs                                     Fbyte_code    
        0.0%    99.8%   Emacs                                      Ffuncall     
        0.0%    99.8%   Emacs                                       
funcall_lambda      
        0.0%    99.8%   Emacs                                        Fbyte_code 
        0.0%    99.8%   Emacs                                         Ffuncall  
        0.0%    99.8%   Emacs                                          
funcall_lambda   
        0.0%    99.8%   Emacs                                           
Fbyte_code      
        0.0%    99.8%   Emacs                                            
Ffuncall       
        0.0%    99.8%   Emacs                                             
Fredisplay
0.0% 99.8% Emacs redisplay_preserve_echo_area 0.0% 99.8% Emacs redisplay_internal 0.0% 99.8% Emacs redisplay_windows 0.0% 99.8% Emacs redisplay_windows 0.0% 99.8% Emacs internal_condition_case_1 0.0% 99.8% Emacs redisplay_window_0 0.0% 99.8% Emacs redisplay_window 0.0% 99.8% Emacs move_it_vertically_backward 0.0% 62.3% Emacs move_it_to 8.9% 62.0% Emacs move_it_in_display_line_to 14.2% 30.5% Emacs x_produce_glyphs 2.1% 9.3% Emacs get_per_char_metric 7.1% 7.1% Emacs nsfont_text_extents 3.3% 6.5% Emacs get_char_face_and_encoding 0.5% 0.5% Emacs take_vertical_position_into_account 0.1% 0.1% Emacs nsfont_text_extents 8.3% 17.5% Emacs get_next_display_element 3.5% 4.4% Emacs set_iterator_to_next 0.4% 0.4% Emacs next_element_from_display_vector 0.1% 0.1% Emacs next_element_from_buffer 0.1% 0.1% Emacs get_char_face_and_encoding 0.0% 0.0% Emacs char_table_ref 0.1% 0.1% Emacs set_iterator_to_next 0.1% 0.1% Emacs x_produce_glyphs 0.1% 0.1% Emacs get_next_display_element 0.0% 0.0% Emacs recenter_overlay_lists 0.0% 37.3% Emacs move_it_by_lines 0.0% 0.1% Emacs back_to_previous_visible_line_start 0.0% 0.0% Emacs line_bottom_y 0.0% 0.0% Emacs try_window 0.0% 0.0% Emacs move_it_by_lines 0.0% 0.0% Emacs prepare_menu_bars 
        0.1%    0.1%    mach_kernel     lo_alltraps     
        0.0%    0.0%    mach_kernel     i386_astintr    
        0.0%    0.0%    mach_kernel     lo_unix_scall   
        0.0%    0.0%    mach_kernel     IOWorkLoop::threadMain()        
        0.0%    0.0%    mach_kernel     thread_continue 
        0.0%    0.0%    mach_kernel     ml_set_interrupts_enabled       
        0.0%    0.0%    mach_kernel     lo_mach_scall
reply via email to
[Prev in Thread] Current Thread [Next in Thread]