[svn.haxx.se] · SVN Dev · SVN Users · SVN Org · TSVN Dev · TSVN Users · Subclipse Dev · Subclipse Users · this month's index

Re: svn commit: r1344347 - /subversion/trunk/subversion/libsvn_subr/config_file.c

From: Ivan Zhakov <ivan_at_visualsvn.com>
Date: Tue, 25 Mar 2014 15:02:33 +0400

On 30 May 2012 20:52, <rhuijben_at_apache.org> wrote:
> Author: rhuijben
> Date: Wed May 30 16:52:36 2012
> New Revision: 1344347
>
> URL: http://svn.apache.org/viewvc?rev=1344347&view=rev
> Log:
> Remove about 15% of the cpu overhead of svnserve and httpd while running the
> test suite by introducing a very simple parser buffer in the config file parser
> code.
>
> The nice clean stream translation code had an 7 times overhead on this very
> performance critical code path, while clients of svnserve and httpd were
> waiting. (Before this patch the this code path used 22% of the cpu time,
> now just 3%)
>
> * subversion/libsvn_subr/config_file.c
> (parse_context_t): Add buffer and position variables. Use EOF as no ungetc var.
> (parser_getc): Skip '\r' characters as we only need the '\n' character for our
> config files. Use EOF as no ungetc var.
> (parse_option,
> parse_section_name): Rename pool argument to scratch_pool.
> (svn_config__parse_file): Create scratch pool and store the file and parse
> ctx in it. Update initialization and destroy scratch_pool after successfull
> parsing.
>
> Modified:
> subversion/trunk/subversion/libsvn_subr/config_file.c
>
> Modified: subversion/trunk/subversion/libsvn_subr/config_file.c
> URL: http://svn.apache.org/viewvc/subversion/trunk/subversion/libsvn_subr/config_file.c?rev=1344347&r1=1344346&r2=1344347&view=diff
> ==============================================================================
> --- subversion/trunk/subversion/libsvn_subr/config_file.c (original)
> +++ subversion/trunk/subversion/libsvn_subr/config_file.c Wed May 30 16:52:36 2012
> @@ -60,15 +60,19 @@ typedef struct parse_context_t
> /* The current line in the file */
> int line;
>
> - /* Cached ungotten character - streams don't support ungetc()
> - [emulate it] */
> + /* Emulate an ungetc */
> int ungotten_char;
> - svn_boolean_t have_ungotten_char;
>
> - /* Temporary strings, allocated from the temp pool */
> + /* Temporary strings */
> svn_stringbuf_t *section;
> svn_stringbuf_t *option;
> svn_stringbuf_t *value;
> +
> + /* Parser buffer for getc() to avoid call overhead into several libraries
> + for every character */
> + char parser_buffer[SVN_STREAM_CHUNK_SIZE]; /* Larger than most config files */
Hi Bert,

Did you have specific reasons for using deprecated
SVN_STREAM_CHUNK_SIZE (100 kb) instead of SVN__STREAM_CHUNK_SIZE
(16kb) constant for read buffer? I'm asking because it seems this
significantly increase memory footprint for high loaded servers due
APR allocator behavior and fragmentation.

I would like change this buffer to 16kb instead of 100kb, if you don't
have strong objections.

-- 
Ivan Zhakov
CTO | VisualSVN | http://www.visualsvn.com
Received on 2014-03-25 12:03:30 CET

This is an archived mail posted to the Subversion Dev mailing list.