Thanks Jan, I have http://git.kiszka.org/?p=linux.git;a=commitdiff;h= 70671bb3cd47fe70b9a7076625e09d0411d58de9 <http://www.google.com/url?q=http%3A%2F%2Fgit.kiszka.org%2F%3Fp%3Dlinux.git%3Ba%3Dcommitdiff%3Bh%3D70671bb3cd47fe70b9a7076625e09d0411d58de9&sa=D&sntz=1&usg=AFQjCNHqW-k5allMU9o8u7ykJebRDcEbvQ> applied at the non-root cell, How can i verify it takes effect? Actually I see clock_getres() still returns low resolution, it is supposed to report 1ns, in case of hires timers.
Dan On 27 February 2017 at 15:32, Jan Kiszka <[email protected]> wrote: > On 2017-02-26 21:47, Dan Zach wrote: > > Made the root cell to be 4.8.2-rt as well. With Jailhouse on, it runs > > the same test with typical jitter of 2-3uS and worse case of 35uS. > > > > > > COUNTER SUM PER > > SEC > > > > vmexits_total 445327 1136 > > vmexits_virt_irq 430071 1107 > > vmexits_mmio 10073 15 > > vmexits_virt_sgi 4552 8 > > vmexits_hypercall 623 7 > > vmexits_management 14 0 > > vmexits_cp15 0 0 > > vmexits_maintenance 0 0 > > vmexits_psci 0 0 > > > > > > > > - Is the root cell handled differently on IRQ handling then non-root? > > Nope. > > > - Why aren't there any CP15 exits, while the non-root cell with the same > > kernel, runs 3.5K/sec on timer rearming? > > The root cell booted with a hardware-provided broadcast timer and, thus, > can switch to hires timer mode (it actually did that prior to loading > Jaihouse). The non-root cell needs the patch Ralf pointed you to already. > > > > > > > And now the interesting part: > > > > _*If the root cell itself*_ runs real-time 1ms task, the non-root cell > > average jitter drops to 12uS (from 50) and worth case to 70uS. > > How about that for a puzzle? > > That can be caching effects (keeping a core busy with cache-bound tasks > means it can request less from RAM and, thus, cause less pressure on > that shared link), or it is related to power management (the idle root > cell may enable power savings that have side effects on other cores). > > Jan > > -- > Siemens AG, Corporate Technology, CT RDA ITP SES-DE > Corporate Competence Center Embedded Linux > -- You received this message because you are subscribed to the Google Groups "Jailhouse" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. For more options, visit https://groups.google.com/d/optout.
