linux-kernel - Re: [PATCH v8 13/14] KVM: selftests: Let dirty_log

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Message-ID: <20200401074821.2tii2x2pzungea44@kamzik.brq.redhat.com>
Date:   Wed, 1 Apr 2020 09:48:21 +0200
From:   Andrew Jones <drjones@...hat.com>
To:     Peter Xu <peterx@...hat.com>
Cc:     linux-kernel@...r.kernel.org, kvm@...r.kernel.org,
        Kevin Tian <kevin.tian@...el.com>,
        "Michael S . Tsirkin" <mst@...hat.com>,
        Jason Wang <jasowang@...hat.com>,
        Sean Christopherson <sean.j.christopherson@...el.com>,
        Christophe de Dinechin <dinechin@...hat.com>,
        Yan Zhao <yan.y.zhao@...el.com>,
        Alex Williamson <alex.williamson@...hat.com>,
        Paolo Bonzini <pbonzini@...hat.com>,
        Vitaly Kuznetsov <vkuznets@...hat.com>,
        "Dr . David Alan Gilbert" <dgilbert@...hat.com>
Subject: Re: [PATCH v8 13/14] KVM: selftests: Let dirty_log_test async for
 dirty ring test

On Tue, Mar 31, 2020 at 02:59:59PM -0400, Peter Xu wrote:
> Previously the dirty ring test was working in synchronous way, because
> only with a vmexit (with that it was the ring full event) we'll know
> the hardware dirty bits will be flushed to the dirty ring.
> 
> With this patch we first introduced the vcpu kick mechanism by using
> SIGUSR1, meanwhile we can have a guarantee of vmexit and also the
> flushing of hardware dirty bits.  With all these, we can keep the vcpu
> dirty work asynchronous of the whole collection procedure now.  Still,
> we need to be very careful that we can only do it async if the vcpu is
> not reaching soft limit (no KVM_EXIT_DIRTY_RING_FULL).  Otherwise we
> must collect the dirty bits before continuing the vcpu.
> 
> Further increase the dirty ring size to current maximum to make sure
> we torture more on the no-ring-full case, which should be the major
> scenario when the hypervisors like QEMU would like to use this feature.
> 
> Signed-off-by: Peter Xu <peterx@...hat.com>
> ---
>  tools/testing/selftests/kvm/dirty_log_test.c  | 126 +++++++++++++-----
>  .../testing/selftests/kvm/include/kvm_util.h  |   1 +
>  tools/testing/selftests/kvm/lib/kvm_util.c    |   9 ++
>  3 files changed, 106 insertions(+), 30 deletions(-)
>

For the vcpu_kick and sem_wait stuff

Reviewed-by: Andrew Jones <drjones@...hat.com>