(sorry for the formatting) On Mon, 10 Dec 2018, 12:00 Andrii Anisov, <andrii.ani...@gmail.com> wrote:
> Hello All, > > On 27.11.18 23:27, Stefano Stabellini wrote: > > See the following: > > > > https://marc.info/?l=xen-devel&m=148668817704668 > So I did port that stuff to the current staging [1]. > Also, the correspondent tbm, itself is here [2]. > Having 4 big cores on my SoC I run XEN with the following command line: > > dom0_mem=3G console=dtuart dtuart=serial0 dom0_max_vcpus=2 > bootscrub=0 loglvl=all cpufreq=none tbuf_size=8192 loglvl=all/none > guest_loglvl=all/none > > The TBM's domain configuration file is as following: > > seclabel='system_u:system_r:domU_t' > name = "DomP" > kernel = "/home/root/ctest-bare.bin" > extra = "console=hvc0 rw" > memory = 128 > vcpus = 1 > cpus = "3" > > This gives me setup where Domain-0 runs on cores 0 and 1 solely and TBM > runs exclusively on core 3. So that we can rely that it shows us a pure IRQ > latency of hypervisor. > My board is Renesas Salvator-X with H3 ES3.0 SoC and 8GB RAM. Generic > timer runs at 8.333 MHz freq, what gives my 120ns resolution for > measurements. > XEN hypervisor is build without debug and TBM does wfi in the idle loop > for all experiments. > With that setup IRQ latency numbers are (in ns): > What are the numbers without Xen? Which version of Xen are you using? > Old vgic: > AVG MIN MAX WARM MAX > credit, vwfi=trap 7706 7560 9480 8400 > credit, vwfi=native 2908 2880 3120 4800 > credit2, vwfi=trap 7221 7200 9240 7440 > credit2, vwfi=native 2906 2880 3120 5040 > > New vgic: > AVG MIN MAX WARM MAX > credit, vwfi=trap 8481 8040 10200 8880 > credit, vwfi=native 4115 3960 4800 4200 > credit2, vwfi=trap 8425 8400 9600 9000 > credit2, vwfi=native 4227 3960 5040 4680 > > Here we can see that the new vgic underperforms the old one in a trivial > use-case modeled with TBM. > The vwfi=trap does not look so bad (10%) but indeed the vwfi=native adds a bigger overhead. This also tells you that in the trap case the vGIC is not the bigger overhead. I am pretty sure that this can be optimized because we mostly focused on reliability and specification compliance for the first draft. So yes the old vGIC performs better but at the price of unreliability and non-compliance. > Old vgic with optimizations [3] (without [4], because it breaks the setup): > AVG MIN MAX WARM MAX > credit, vwfi=trap 7309 7080 8760 7680 > credit, vwfi=native 3007 3000 4320 3120 > credit2, vwfi=trap 6877 6720 8880 7200 > credit2, vwfi=native 2680 2640 4440 2880 > This is with all your series applied but [4], correct? Did you try to see the perfomance improvement patch by patch? Cheers > > > [1] https://github.com/aanisov/xen/tree/4tbm > [2] https://github.com/aanisov/tbm/commits/4xen > [3] > https://lists.xenproject.org/archives/html/xen-devel/2018-11/msg03328.html > [4] > https://lists.xenproject.org/archives/html/xen-devel/2018-11/msg03288.html > > -- > Sincerely, > Andrii Anisov. > > _______________________________________________ > Xen-devel mailing list > Xen-devel@lists.xenproject.org > https://lists.xenproject.org/mailman/listinfo/xen-devel
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