On Thu 2018-01-04 21:23:59, Alan Cox wrote: > On Thu, 4 Jan 2018 21:39:24 +0100 (CET) > Jiri Kosina <jikos@xxxxxxxxxx> wrote: > > > On Thu, 4 Jan 2018, Alan Cox wrote: > > > > > You never go from one user process to another except via the kernel. We > > > have no hardware scheduling going on. That means that if the kernel > > > and/or CPU imposes the correct speculation barriers you can't attack > > > anyone but yourself. > > > > So how does this work on HT with the shared BTB? There is no context > > switch (and hence no IBPB) happening between the threads sharing it. > > > > If you are paranoid in that case you either need to schedule things that > trust each other together or disable the speculation while that situation > occurs. However the kernel is always in the position to make that > decision. Actually... I'm not paranoid but would like to run flightgear on one core (smt cpu #0), with smt cpu#1 being idle, while running compilations on second core (smt cpus #2 and #3). Is there easy way to do that? Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html
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