DISCLAIMER. English language used here only for compatibility (ASCII only), so any suggestions about my bad grammar (and not only it) will be greatly appreciated.

понедельник, 31 января 2011 г.

Speed comparison for some framebuffer drivers

Speed comparison for frambuffer drivers (uvesafb, vesafb) in two modes:
    - with 8bpp  (1680x1050-8@60) and
    - with 32bpp (1680x1050-32@60).


 *========*=============================================================================================*
 #   \    #                                        scroll method                                        #
 #     \  #-------------------------------*------------------------------*------------------------------*
 # mtrr  \# redraw                        | ypan                         | ywrap                        # 
 *--------*===============================*==============================*==============================*
 #        #                                       uvesafb                                               #
 #        #                                      ---------                                              #
 # 0      #                               #                              # (2.180s, --) @ (12.261s, fb) #
 # 2 (wb) # (15.010s, --) @ (58.550s, fb) # (2.180s, --) @ (12.155s, fb) # (2.180s, --) @ (12.157s, fb) #
 # 3 (wc) # (2.202s,  --) @ (4.230s,  --) # (1.011s, --) @ (6.715s,  -b) # (1.011s, --) @ (6.720s,  -b) #
 *========*=============================================================================================*
 #        #                                       vesafb                                                #
 #        #                                      --------                                               #
 # 0      #                               #                              #                              #
 # 2 (wb) #                               #                              # (3.181s, ??) @ (12.305s, ??) #
 # 3 (wc) # (2.256s,  ??) @ (4.312s,  ??) # (0.235s, ??) @               # (0.289s, ??) @ (6.762s,  ??) #
 *========*=============================================================================================*
 vga text console = (1.263s, --)

 where

    (`cat`_time, [forward_scroll_lag][backward_scroll_lag]) @ (  ...   )
                  8 bpp                                     @   32 bpp

    (TIMEs, [f-][b-]) @ (..)
        
        () @    before @ is measurements for 8bpp mode.
        @ ()    after @ is measurements for 32bpp mode.
        TIME    is real time for command `time cat kernel-parameters.txt`.
        f       means that forward scroll lags in `less` or `vim`.
        b       means that backward scroll lags in `less` or `vim`.
        -       means that scroll in corresponding direction does not lag.


Notes:
    - As expected 'ypan'/'ywrap' scroll methods are faster than 'redraw' for
      both 8bpp and 32bpp with mtrr=2. But with mtrr=3 for 32bpp unexpectedly
      'redraw' scroll method becomes the fastest. Though for 8bpp situation
      remains the same.
    - Also, that's strange, but i don't notice any scroll lag with 'redraw'
      scroll and mtrr=2 for 8bpp, though `cat` time for this mode is long
      enough.
    - results for vesafb is almost the same as for uvesafb, though `cat` time
      for 8bpp with mtrr=3 and 'ywrap'/'ypan' scroll is even lesser (and,
      also, suprisingly lesser, than for vga text console).
    - For mtrr=4 results are the same as for mtrr=2.

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