Re: XeConTeXt bug report I: strange benchmark

[Yue Wang <yuleopen@gmail.com>]

On Tue, May 12, 2009 at 10:50 PM, Hans Hagen <pragma@wxs.nl> wrote:
> Yue Wang wrote:
>>
>> On Tue, May 12, 2009 at 8:54 PM, Hans Hagen <pragma@wxs.nl> wrote:
>>>
>>> Yue Wang wrote:
>>>
>>>
>>>> moreover, can you tell me why pdftex load these fonts so fast? (also 6
>>>> families * 3 sizes)
>>>
>>> i don't know; as the same code is used so it must be xetex itself then
>>
>> Then let me tell you why: ConTeXt tries to load lmmono10-regular at
>> least 6 times, failed after two testing, then succeed in the end.
>> However, try to testing whether a loaded font is \nullfont or not is
>> quite slow in XeTeX (Jonathan already mentioned that in
>> \testFontIsAvailable). we should definately avoid that.
>> But why pdftex is so fast? because it does not involve font testing.
>>
>> So why XeTeX is spending 6 seconds aimlessly? since ConTeXt asked it
>> to search for a non-existed font.
>
> well, even locating a font 6 times should be no big deal
>


loading 6 fonts, each fonts will be scanned for 3 times. so there are
18 searching. 12 of them are fc searches, and these are quite slow.

> btw, you can try to change the following into
>
> \def\defaultfontfile{file:lmmono10-regular}
>

After changing like this, XeTeX runs like a blink. (It wasted 6
seconds for each compile. now it won't)

> but even then ... if that one is used then there is something else going on
> so best find out what happens ... in context we can have 4 extra math
> families and in most cases only two are used (MathAlpha and MathBeta) while
> (just in onder to catch errors) MathGamma etc then automatically will
> trigger the default font to be used (other approached would demand more
> definitions at the user end and/or a more low level implementation); the
> only optimization i can imagine is more clever sharing of the default font
> but as in other cases one expects the default to be properly scaled it not
> that simple; after all, users also expect proper error recovery (and in many
> cases missing some specific fonts is no real problem until it's used); so,
> you can hardly blame context for the fact that xetex has a certain logix on
> locating fonts that happens to be not that good a match for context
>
> The fact that xetex uses this mixture of "" en [] does not help either as
> context uses [] itself so parsing is somewhat complicated (the file/name
> prefix was introduced to circumvent this problem);
>
> Hans
>
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