From mboxrd@z Thu Jan 1 00:00:00 1970 From: =?utf-8?B?SsO2cm4=?= Engel Subject: Re: Not as much ccache win as I expected Date: Sun, 15 Jun 2008 19:58:35 +0200 Message-ID: <20080615175835.GA15244@logfs.org> References: <4852C51D.30206@am.sony.com> <8499950a0806131354u7d2431b2n2df50b7b6c98f18d@mail.gmail.com> <4852E245.4020502@am.sony.com> Mime-Version: 1.0 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: Content-Disposition: inline In-Reply-To: <4852E245.4020502@am.sony.com> Sender: linux-kbuild-owner@vger.kernel.org List-ID: Content-Type: text/plain; charset="iso-8859-1" To: Tim Bird Cc: Oleg Verych , linux-embedded , linux-kbuild@vger.kernel.org On Fri, 13 June 2008 14:10:29 -0700, Tim Bird wrote: >=20 > Maybe I should just be grateful for any ccache hits I get. ccache's usefulness depends on your workload. If you make a change to include/linux/fs.h, close to 100% of the kernel is rebuilt, with or without ccache. But when you revert that change, the build time differ= s dramatically. Without ccache, fs.h was simply changed again and everything is rebuild. With ccache, there are hits for the old version and all is pulled from the cache - provided you have allotted enough disk for it. If you never revert to an old version or do some equivalent operation, ccache can even be a net loss. On a fast machine, the additional disk accesses are easily more expensive than the minimal cpu gains. J=C3=B6rn --=20 Public Domain - Free as in Beer General Public - Free as in Speech BSD License - Free as in Enterprise Shared Source - Free as in "Work will make you..." -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild"= in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html