On Tue, Jul 26, 2022 at 3:27 AM Paolo Bonzini <pbonzini@xxxxxxxxxx> wrote: > > On 7/26/22 10:33, Andrei Vagin wrote: ... > > == Execute system calls from a user-space VMM == > > > > In this case, the Sentry is always running in VM, and a syscall handler in GR0 > > triggers vmexit to transfer control to VMM (user process that is running in > > hr3), VMM executes a required system call, and transfers control back to the > > Sentry. We can say that it implements the suggested hypercall in the > > user-space. > > > > The sentry syscall time is 2100ns in this case. > > > > The new hypercall does the same but without switching to the host ring 3. It > > reduces the sentry syscall time to 1000ns. > > Yeah, ~3000 clock cycles is what I would expect. > > What does it translate to in terms of benchmarks? For example a simple > netperf/UDP_RR benchmark. * netperf in gVisor with the syscall fast path: $ ./runsc --platform kvm --network host --rootless do netperf -H ::1 -p 12865 -t UDP_RR MIGRATED UDP REQUEST/RESPONSE TEST from ::0 (::) port 0 AF_INET6 to ::1 (::1) port 0 AF_INET6 : interval : first burst 0 Local /Remote Socket Size Request Resp. Elapsed Trans. Send Recv Size Size Time Rate bytes Bytes bytes bytes secs. per sec 212992 212992 1 1 10.00 95965.18 212992 212992 * netperf in gVisor without syscall fast path: $ ./runsc.orig --platform kvm --network host --rootless do netperf -H ::1 -p 12865 -t UDP_RR MIGRATED UDP REQUEST/RESPONSE TEST from ::0 (::) port 0 AF_INET6 to ::1 (::1) port 0 AF_INET6 : interval : first burst 0 Local /Remote Socket Size Request Resp. Elapsed Trans. Send Recv Size Size Time Rate bytes Bytes bytes bytes secs. per sec 212992 212992 1 1 10.00 58709.17 212992 212992 * netperf executed on the host without gVisor $ netperf -H ::1 -p 12865 -t UDP_RR MIGRATED UDP REQUEST/RESPONSE TEST from ::0 (::) port 0 AF_INET6 to ::1 (::1) port 0 AF_INET6 : interval : first burst 0 Local /Remote Socket Size Request Resp. Elapsed Trans. Send Recv Size Size Time Rate bytes Bytes bytes bytes secs. per sec 212992 212992 1 1 10.00 146460.80 212992 212992 Thanks, Andrei
