From mboxrd@z Thu Jan 1 00:00:00 1970 From: Simon Glass Date: Sat, 15 Feb 2014 19:51:34 -0700 Subject: [U-Boot] [PATCH v8 0/38] Switch over to real Kbuild In-Reply-To: References: <1390998395-18567-1-git-send-email-yamada.m@jp.panasonic.com> <20140203124630.481C.AA925319@jp.panasonic.com> <20140206211012.GI7049@bill-the-cat> Message-ID: List-Id: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: u-boot@lists.denx.de Hi Masahiro, On 15 February 2014 18:30, Simon Glass wrote: > Hi Masahiro, > > On 6 February 2014 14:10, Tom Rini wrote: >> On Mon, Feb 03, 2014 at 12:46:30PM +0900, Masahiro Yamada wrote: >> >>> Hello Simon and Tom, >>> >>> >>> This is my analysis of Kbuild performance. >> [snip] >>> Conclusion: >>> The main reasons of the slow down with Kbuild are "fixdep" and "arg-check". >>> Both of them are really important features for Kbuild and Kconfig. >>> - "fixdep" is mandatory for our better life with Kconfig. >>> - "arg-check" is for perfect dependency tracking. >>> > > Thanks for your detailed analysis of this. The slower build time is > unfortunate but I think it is worth it. The fixdep thing is similar to > the penalty from the autoconf series I did a while ago. Maybe the > scripts can be sped up, I'm not sure. I'm not sure whether to start a new thread or not, but here in one observations which might be useful. With current master, a 'null' build (with nothing changed) takes about 5s for me. time CROSS_COMPILE=/opt/linaro/gcc-linaro-arm-linux-gnueabihf-4.8-2013.08_linux/bin/arm -linux-gnueabihf- ARCH=arm make -j1 real 0m4.978s user 0m1.144s sys 0m0.360s With the kbuild series, it takes a lot longer: real 0m46.600s user 0m17.628s sys 0m8.664s There seem to be noticeable pauses between things happening. I'm not quite sure how to dig into it more. Is it possible that cc-option is no-longer caching the various compiler options? Regards, Simon