Re: [PATCH] Add 2-pass mode to gtags

[Hideki IWAMOTO]

Hi.

> Since there are a lot of changes in the parser, the output should be seen by
> a lot of people before the formal release, I think.

When bree cache is small, current implementation of 2-pass mode is slower than 
default mode.

$ foreach cpumask ( 1 3 )
foreach? foreach label ( default 2pass )
foreach? echo ==== cpumask:$cpumask label:$label ====
foreach? foreach cachesize ( 8388608 16777216 33554432 67108864 )
foreach? rm -fr linux-2.6.31; tar xfj ~/download/linux/linux-2.6.31.tar.bz2; 
sync
foreach? (cd linux-2.6.31; time taskset $cpumask env GTAGSLABEL=$label 
GTAGSCACHE=$cachesize gtags)
foreach? end
foreach? end
foreach? end
==== cpumask:1 label:default ====
114.267u 24.085s 3:09.48 73.0%  0+0k 0+0io 1pf+0w
115.367u 20.521s 2:55.73 77.3%  0+0k 0+0io 0pf+0w
116.227u 18.081s 2:32.98 87.7%  0+0k 0+0io 0pf+0w
116.671u 16.093s 2:24.36 91.9%  0+0k 0+0io 0pf+0w
==== cpumask:1 label:2pass ====
91.353u 19.205s 3:48.79 48.3%   0+0k 0+0io 0pf+0w
92.317u 16.501s 3:05.40 58.6%   0+0k 0+0io 0pf+0w
92.797u 13.580s 2:08.52 82.7%   0+0k 0+0io 0pf+0w
93.929u 11.080s 1:56.03 90.4%   0+0k 0+0io 0pf+0w
==== cpumask:3 label:default ====
112.507u 23.593s 2:48.80 80.6%  0+0k 0+0io 1pf+0w
112.991u 18.965s 2:30.06 87.9%  0+0k 0+0io 0pf+0w
113.591u 17.305s 2:13.30 98.1%  0+0k 0+0io 0pf+0w
114.831u 16.113s 2:11.92 99.2%  0+0k 0+0io 0pf+0w
==== cpumask:3 label:2pass ====
88.773u 18.929s 3:17.01 54.6%   0+0k 0+0io 0pf+0w
90.085u 15.108s 2:35.38 67.6%   0+0k 0+0io 0pf+0w
90.877u 12.204s 1:44.62 98.5%   0+0k 0+0io 0pf+0w
91.217u 10.540s 1:29.74 113.3%  0+0k 0+0io 0pf+0w

It seems that moving use of defined() from gtags-parser to gtags is bad idea.
I will reimplement 2-pass mode in another way.
Since new 2-pass mode is implemented by adding tag type to output of 
gtags-parser,
the specifications of parser will be compatible with default mode.


On Thu, 22 Oct 2009 15:44:28 +0900, Shigio YAMAGUCHI wrote...
> Hi Hideki,
> 
> > To improve the performance of gtags, this patch adds 2-pass mode. 
> > 
> > The following three points are improved by moving use of function defined()
> > from gtags-parser to gtags. 
> >  1. Decreases the frequency of parsing source file from three times to two 
> > times.
> >  2. Decreases reading of GTAGS by keeping cache of GTAGS
> >     beyond the duration of parser process. 
> >  3. Increases parallelism of gtags-parser and gtags on multiprocessor 
> > system. 
> 
> Great!!! I named your code 'Giant steps'.
> 
> Since there are a lot of changes in the parser, the output should be seen by
> a lot of people before the formal release, I think.
> How about releasing twice like follows?
> 
>                         include Giant steps?    enable Giant steps by default?
> ------------------------------------------------------------------------------
> GLOBAL-5.7.7(beta)      Yes                     No
> GLOBAL-5.8(formal)      Yes                     Yes
> 
> Thank you for your wonderful 'Giant steps'!
> --
> Shigio YAMAGUCHI <address@hidden>
> PGP fingerprint: D1CB 0B89 B346 4AB6 5663  C4B6 3CA5 BBB3 57BE DDA3

----
Hideki IWAMOTO  address@hidden