Re: Display performance degradation

[Jan Djärv]

YAMAMOTO Mitsuharu skrev:
> I can observe significant display performance degradation on Emacs
> 23.1.90 compared with 23.1, especially when scrolling TUTORIAL.ja on a
> frame that uses the xft font backend.  I also observe the increase of
> the total number of xftfont_draw calls, and a string in a single font
> and color, which was originally displayed by one call, is now
> unnecessarily divided into smaller units.

Can you try again?  I've reinstored the part below, but with some changes.

Thanks,

        Jan D.

> As an experiment, I tried restoring the following change, and then the
> performance became comparable to 23.1.
>
> 2009-11-17  Jan Djärv  <address@hidden>
>
>         * font.c (font_open_entity): Do not use cache, it does not pick up new
>         fontconfig settings like hinting.
>
> *** 2975,2985 ****
> --- 2987,3001 ----
>     else if (CONSP (Vface_font_rescale_alist))
>       scaled_pixel_size = pixel_size * font_rescale_ratio (entity);
>   
> + #if 0
> +   /* This doesn't work if you have changed hinting or any other parameter.
> +      We need to make a new object in every case to be sure. */
>     for (objlist = AREF (entity, FONT_OBJLIST_INDEX); CONSP (objlist);
>          objlist = XCDR (objlist))
>       if (! NILP (AREF (XCAR (objlist), FONT_TYPE_INDEX))
>         && XFONT_OBJECT (XCAR (objlist))->pixel_size == pixel_size)
>         return  XCAR (objlist);
> + #endif
>   
>     val = AREF (entity, FONT_TYPE_INDEX);
>     for (driver_list = f->font_driver_list;
>
> The added comment implies that the simple removal of #if 0 causes
> another problem for some cases, but I think creating a new font object
> for each call is too much for the usual cases.  Perhaps this part
> needs some improvement.
>
>                                      YAMAMOTO Mitsuharu
>                                 address@hidden