All of lore.kernel.org
 help / color / mirror / Atom feed
* About the operator "??="
@ 2010-12-01  1:57 Xu, Dongxiao
  2010-12-08 10:30 ` Richard Purdie
  0 siblings, 1 reply; 19+ messages in thread
From: Xu, Dongxiao @ 2010-12-01  1:57 UTC (permalink / raw)
  To: Richard Purdie; +Cc: poky@yoctoproject.org

Hi Richard,

Recently when investigating the file parsing speed, I found the implementation of "??=" is another hot spot. This operator will not apply the default assignment until the end of the parse, which is different from "?=". According to current poky, the users for "??=" is mostly the scm revisions stored in poky-default-revisions.inc.

Currently the final assignment logic for "??=" is added in finalize(), which costs about 20% parsing time. 

The differences between "??=" and "?=" are straight forward, however I don't fully understand in which senario the "??=" should be used. Or in other word, why those scm revisions should use "??=". Could you help to clarify a bit? Thanks so much!

BTW, I noticed that openembedded doesn't use this operator.

Best Regards,
-- Dongxiao 

^ permalink raw reply	[flat|nested] 19+ messages in thread
* Re: About the operator "??="
@ 2010-12-08  3:00 Xu, Dongxiao
  0 siblings, 0 replies; 19+ messages in thread
From: Xu, Dongxiao @ 2010-12-08  3:00 UTC (permalink / raw)
  To: Richard Purdie; +Cc: poky@yoctoproject.org

Hi Richard,

Do you have comments on this one?

Thanks,
Dongxiao

Xu, Dongxiao wrote:
> Hi Richard,
> 
> Recently when investigating the file parsing speed, I found the
> implementation of "??=" is another hot spot. This operator will not
> apply the default assignment until the end of the parse, which is
> different from "?=". According to current poky, the users for "??="
> is mostly the scm revisions stored in poky-default-revisions.inc.    
> 
> Currently the final assignment logic for "??=" is added in
> finalize(), which costs about 20% parsing time. 
> 
> The differences between "??=" and "?=" are straight forward, however
> I don't fully understand in which senario the "??=" should be used.
> Or in other word, why those scm revisions should use "??=". Could you
> help to clarify a bit? Thanks so much!   
> 
> BTW, I noticed that openembedded doesn't use this operator.
> 
> Best Regards,
> -- Dongxiao



^ permalink raw reply	[flat|nested] 19+ messages in thread

end of thread, other threads:[~2010-12-13 16:24 UTC | newest]

Thread overview: 19+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2010-12-01  1:57 About the operator "??=" Xu, Dongxiao
2010-12-08 10:30 ` Richard Purdie
2010-12-08 11:35   ` Tian, Kevin
2010-12-08 11:59     ` Xu, Dongxiao
2010-12-08 14:37       ` Richard Purdie
2010-12-09  3:32         ` Xu, Dongxiao
2010-12-09  4:57           ` Tian, Kevin
2010-12-09  7:59             ` Xu, Dongxiao
2010-12-09 11:24               ` Richard Purdie
2010-12-09 12:13                 ` Xu, Dongxiao
2010-12-09 12:45                   ` Richard Purdie
2010-12-09 14:44                     ` Xu, Dongxiao
2010-12-10 23:42                       ` Richard Purdie
2010-12-10 23:58                         ` Chris Larson
2010-12-13 16:24                           ` Scott Garman
2010-12-11  2:48                         ` Xu, Dongxiao
2010-12-08 12:49     ` Tian, Kevin
2010-12-08 13:02       ` Xu, Dongxiao
  -- strict thread matches above, loose matches on Subject: below --
2010-12-08  3:00 Xu, Dongxiao

This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.