From: "Jörn Engel" <joern@logfs.org>
To: Tim Bird <tim.bird@am.sony.com>
Cc: Oleg Verych <olecom@gmail.com>,
linux-embedded <linux-embedded@vger.kernel.org>,
linux-kbuild@vger.kernel.org
Subject: Re: Not as much ccache win as I expected
Date: Sun, 15 Jun 2008 19:58:35 +0200 [thread overview]
Message-ID: <20080615175835.GA15244@logfs.org> (raw)
In-Reply-To: <4852E245.4020502@am.sony.com>
On Fri, 13 June 2008 14:10:29 -0700, Tim Bird wrote:
>
> 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 differs
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.
Jörn
--
Public Domain - Free as in Beer
General Public - Free as in Speech
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Shared Source - Free as in "Work will make you..."
prev parent reply other threads:[~2008-06-15 17:58 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-06-13 19:06 Not as much ccache win as I expected Tim Bird
2008-06-13 20:54 ` Oleg Verych
2008-06-13 21:10 ` Tim Bird
2008-06-15 17:58 ` Jörn Engel [this message]
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