Date: Mon, 16 May 2005 18:00:31 +1000 From: Peter Jeremy <peterjeremy@optushome.com.au> To: Nate Lawson <nate@root.org> Cc: Colin Percival <cperciva@freebsd.org> Subject: Re: cvs commit: src/sys/amd64/amd64 mp_machdep.csrc/sys/amd64/include cpufunc.h src/sys/i386/i386 mp_machdep.c src/sys/i386/include cpufunc.h Message-ID: <20050516080031.GD34537@server.vk2pj.dyndns.org> In-Reply-To: <4287AD84.6070600@root.org> References: <97079.1116154766@critter.freebsd.dk> <4287AD84.6070600@root.org>
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On Sun, May 15, 2005 at 01:13:56PM -0700, Nate Lawson wrote: >My point was that FreeBSD (like most general-purpose OS) has many timing >channels that are comparably as effective for an attacker as HTT. If you take the bandwidth of the timing channel into account, I don't believe there are any other timing channels that come anywhere near the HTT attack. Maybe Colin has a better idea of what other timing channels exist and how they compare to HTT. >Disabling HTT does not significantly reduce an attacker's likelihood of >success since they can just use another timing channel. However, it >does disable a useful feature. Are we going to disable SMP next? How useful is HTT on FreeBSD? FreeBSD does not have a HTT-aware scheduler at present and I don't believe there are even any plans to make either scheduler HTT-aware. Without this, you only gain a benefit if you are running fairly specific workloads. Peter
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