Re: [PATCH] tags: much faster, parallel "make tags"
From: Michal Marek
Date: Wed Apr 15 2015 - 05:37:01 EST
On 2015-04-14 22:24, Guenter Roeck wrote:
> On Tue, Apr 14, 2015 at 01:05:09PM -0700, Randy Dunlap wrote:
>> On 04/14/15 10:20, Alexey Dobriyan wrote:
>>> ctags is single-threaded program. Split list of files to be tagged into
>>> equal parts, 1 part for each CPU and then merge the results.
>>> Speedup on one 2-way box I have is ~143 s => ~99 s (-31%).
>>> On another 4-way box: ~120 s => ~65 s (-46%!).
>>> Resulting "tags" files aren't byte-for-byte identical because ctags
>>> program numbers anon struct and enum declarations with "__anonNNN"
>>> symbols. If those lines are removed, "tags" file becomes byte-for-byte
>>> identical with those generated with current code.
>>> Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
>>> scripts/tags.sh | 34 ++++++++++++++++++++++++++++++++--
>>> 1 file changed, 32 insertions(+), 2 deletions(-)
>>> --- a/scripts/tags.sh
>>> +++ b/scripts/tags.sh
>>> @@ -152,7 +152,24 @@ dogtags()
>>> - all_target_sources | xargs $1 -a \
>>> + NR_CPUS=1
>>> + if [ -e /proc/cpuinfo ]; then
>>> + NR_CPUS=$(grep -e '^processor : ' /proc/cpuinfo | wc -l)
>> That grep is rather arch-specific. If an arch does not have that string
>> (with an embedded tab), won't NR_CPUS be zero? so at least, set it back to 1?
>> or (if 'getconf' is installed):
>> NR_CPUS = `getconf _NPROCESSORS_ONLN`
> What is wrong with nproc ?
It's too new. 'getconf _NPROCESSORS_ONLN' has been available since 1996
according to glibc.git.
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/