Date: Sat, 11 Jun 2011 13:49:47 -0700 From: Doug Barton <dougb@FreeBSD.org> To: Kostik Belousov <kostikbel@gmail.com> Cc: Adrian Chadd <adrian@freebsd.org>, freebsd-arch@freebsd.org Subject: Re: [RFC] shipping kernels with default modules? Message-ID: <4DF3D4EB.5030805@FreeBSD.org> In-Reply-To: <20110611201703.GO48734@deviant.kiev.zoral.com.ua> References: <BANLkTin2AwKRT7N6HWqBctJcT72_mR=Otg@mail.gmail.com> <4DF3B532.6020908@FreeBSD.org> <D76B9160-327F-454F-AAD2-567D837BCD68@bsdimp.com> <20110611201703.GO48734@deviant.kiev.zoral.com.ua>
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On 6/11/2011 1:17 PM, Kostik Belousov wrote: > On Sat, Jun 11, 2011 at 02:00:20PM -0600, Warner Losh wrote: >> >> On Jun 11, 2011, at 12:34 PM, Doug Barton wrote: >>> On 6/11/2011 2:21 AM, Adrian Chadd wrote: >>>> Hi guys, >>>> >>>> Has there been any further thought as of late about shipping kernels >>>> with modules only by default, rather than monolithic kernels? >>>> >>>> I tried this experiment a couple years ago and besides a little >>>> trickery with ACPI module loading, it worked out fine. >>>> >>>> Is there any reason we aren't doing this at the moment? Eg by having a >>>> default loader modules list populated from the kernel config file? >>> >>> Has anyone benchmarked monolithic vs. modular? I think that should be done before we move in this direction. >> >> I haven't noticed a difference, but I haven't done any specific benchmarking. > > There might be some measurable difference on i386, where we use dso for > modules. As a consequence, the overhead of GOT/PLT indirection, and, more > important, stolen %ebx on the register-starved architecture, may make > a difference. I doubt that any difference can be measured on amd64. And no one has ever been surprised that assumptions proved invalid in the light of actual testing? :) Theorizing on this point is of less-than-zero utility. Who is going to volunteer to do the actual benchmarking? Doug -- Nothin' ever doesn't change, but nothin' changes much. -- OK Go Breadth of IT experience, and depth of knowledge in the DNS. Yours for the right price. :) http://SupersetSolutions.com/
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