On Mon, Mar 09, 2020 at 06:25:34PM -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@xxxxxxxxxx>
> ---
> 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(-)
>
> diff --git a/tools/testing/selftests/kvm/dirty_log_test.c b/tools/testing/selftests/kvm/dirty_log_test.c
> index 134637267af4..b07e52858e87 100644
> --- a/tools/testing/selftests/kvm/dirty_log_test.c
> +++ b/tools/testing/selftests/kvm/dirty_log_test.c
> @@ -13,6 +13,9 @@
> #include <time.h>
> #include <pthread.h>
> #include <semaphore.h>
> +#include <sys/types.h>
> +#include <signal.h>
> +#include <errno.h>
> #include <linux/bitmap.h>
> #include <linux/bitops.h>
> #include <asm/barrier.h>
> @@ -59,7 +62,9 @@
> # define test_and_clear_bit_le test_and_clear_bit
> #endif
>
> -#define TEST_DIRTY_RING_COUNT 1024
> +#define TEST_DIRTY_RING_COUNT 65536
> +
> +#define SIG_IPI SIGUSR1
>
> /*
> * Guest/Host shared variables. Ensure addr_gva2hva() and/or
> @@ -135,6 +140,12 @@ static uint64_t host_track_next_count;
> /* Whether dirty ring reset is requested, or finished */
> static sem_t dirty_ring_vcpu_stop;
> static sem_t dirty_ring_vcpu_cont;
> +/*
> + * This is updated by the vcpu thread to tell the host whether it's a
> + * ring-full event. It should only be read until a sem_wait() of
> + * dirty_ring_vcpu_stop and before vcpu continues to run.
> + */
> +static bool dirty_ring_vcpu_ring_full;
>
> enum log_mode_t {
> /* Only use KVM_GET_DIRTY_LOG for logging */
> @@ -156,6 +167,33 @@ enum log_mode_t {
> static enum log_mode_t host_log_mode_option = LOG_MODE_ALL;
> /* Logging mode for current run */
> static enum log_mode_t host_log_mode;
> +pthread_t vcpu_thread;
> +
> +/* Only way to pass this to the signal handler */
> +struct kvm_vm *current_vm;
nit: above two new globals could be static
