Re: [ft] Minimizing small file reads

[☂Josh Chia (谢任中)]

Hi 

If you're talking about mmap(), yes my system has mmap, but I'll have to check whether I have it enabled in my freetype build.  I notice that freetype is reading little pieces of data, like a long here and there.  I also see larger chunks of 4k being read, but ideally, I would like to have everything in memory so that I don't need any calls to read() after some initial read(s).  Perhaps, there's a way to prefetch entire font files?

If mmap() can be used to avoid small reads, I should probably investigate how to make use of it.

Josh

On Mon, Nov 17, 2008 at 9:34 PM, suzuki toshiya <address@hidden> wrote:

Hi,

In the system supporting memmap() and FreeType2 is configured
to use it, the number of system call would be much reduced in
comparison with the system without memmap. In the target platform
which you're working for, memmap() is available? Or, available
and configured to use it, but you think still too many read
system call is executed?

Regards,
mpsuzuki

☂Josh Chia (谢任中) wrote (2008/11/18 10:39):

Hi,

I notice that freetype makes a lot of small reads, resulting in a lot of
SYS_read calls.  I'm using freetype in an app that runs in a ptrace sandbox,
so performance is sensitive to system calls.  Is there a simple way to
prevent the numerous small reads (via ft_ansi_stream_io), such as
configuring freetype to prefetch into a large buffer when reading, and
making it assume that font files never change?  Will I need to make some
configuration changes or do I need to make code changes?  Thanks!

Josh

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