On Tue, 29 Oct 2024 17:06:09 +0000, Raghavendra Rao Ananta <rananta@xxxxxxxxxx> wrote: > > On Tue, Oct 29, 2024 at 9:27 AM Marc Zyngier <maz@xxxxxxxxxx> wrote: > > > > On Mon, 28 Oct 2024 23:45:33 +0000, > > Raghavendra Rao Ananta <rananta@xxxxxxxxxx> wrote: > > > > > Did you have a chance to check whether this had any negative impact on > > actual workloads? Since the entry/exit code is a bit of a hot spot, > > I'd like to make sure we're not penalising the common case (I only > > wrote this patch while waiting in an airport, and didn't test it at > > all). > > > I ran the kvm selftests, kvm-unit-tests and booted a linux guest to > test the change and noticed no failures. > Any specific test you want to try out? My question is not about failures (I didn't expect any), but specifically about *performance*, and whether checking the flag without a static key can lead to any performance drop on the hot path. Can you please run an exit-heavy workload (such as hackbench, for example), and report any significant delta you could measure? Thanks, M. -- Without deviation from the norm, progress is not possible.
