William,
thanks for the idea. But I'd expect memory demands to rise
considerably, could you give some details on that? Does the 20% speed
gain pay off? The current Str handling is sort of the best time-space
compromise we managed to find. In particular, we tried to reduce the
load on the heap manager by implementing a memory arena where the
strings reside, which has helped a lot.
Tom Kaiser
> "Lee, William" wrote:
>
> Hi there,
>
> I'm working with the Sablotron 0.44 performance... and found out that
> most of the time it is spending on allocating little trunk of memory
> for small string and for appending small strings...
>
> To speed up the performance in this area, I have implement a new
> string class, which replaced both existing DStr and Str classes. The
> idea is as follows:
>
> Each Str object will now contains a pre-allocated buffer of size 1K
> (customizable in the source code, but 1K is the optimal so far to
> avoid stack overflow)... Any string assignment/append with work with
> this buffer unless it caused an overflow, and in that case, a dynamic
> allocated buffer will be used. The size of the dynamic allocated
> buffer is round up to the nearest 4K (again, customizable in the
> source code), and again, any string concatenation will be done within
> the same buffer, and will be "reallocated" to a bigger size when a
> bigger one is need.
>
> I have run some performance testing against the release/optimized
> version, and the result are:
> a small one (xml ~90K and xsl ~80K) which took 1050ms before
> is now takes only 800ms
> a medium size one (xml ~ 300K and xsl ~80K) improved from
> 2200ms to 1800 ms
> (i.e., the average is around 20% improvement).
>
> Since I'm new to this mailing list, could anyone let me know what is
> the procedure/steps to follows for this kind of changes? Or how can I
> submit the changes in order to get accepted/approved by the group?
>
> Also, I believed the following is a bug in datastr.cpp:
>
> int Str::compare(const char* otherChars) const
> {
> return (strcmp(operator char*(), otherChars) < 0);
> }
>
> which I believed it should be:
>
> int Str::compare(const char* otherChars) const
> {
> return (strcmp(operator char*(), otherChars));
> }
>
> Thanks in advance for your help.
> William Lee
>
> Name: datastr.cpp
> datastr.cpp Type: Emacs File
> (application/x-unknown-content-type-cppfile)
> Encoding: quoted-printable
>
> Name: datastr.h
> datastr.h Type: C Header file
> (application/x-unknown-content-type-hfile)
> Encoding: quoted-printable
