Re: big latency while under HV
From: Diana Craciun <hidden>
Date: 2013-09-10 09:24:45
Hi, Just to be on the same page, are you using the Freescale Embedded Hypervisor provided with the Freescale SDK or other embedded hypervisor? Anyway, the question is not much related with the Linux kernel, so you should probably redirect your question to Freescale support. You can reach Freescale support at support@freescale.com. Diana On 09/09/2013 06:19 PM, Ivan Krivonos wrote:
Hi, i`m working on the embedded hypervisor targeting QorIQ platforms (p3041/p4080). I have working prototype starting custom RTOS on just single core in the guest space. What I see is the big latency (up to 3 times more) in RTOS running atop of HV comparing to RTOS running bare-metal. I`m using lmbench utility. It shows nteger mul: 3.48 nanoseconds integer div: 30.44 nanoseconds integer mod: 13.92 nanoseconds int64 bit: 1.75 nanoseconds int64 add: 1.42 nanoseconds int64 mul: 6.95 nanoseconds HV:hvpriv_count 60000 int64 div: 447.56 nanoseconds int64 mod: 385.42 nanoseconds float add: 7.12 nanoseconds float mul: 6.95 nanoseconds float div: 33.05 nanoseconds double add: 7.11 nanoseconds double mul: 8.70 nanoseconds double div: 57.36 nanoseconds float bogomflops: 46.98 nanoseconds double bogomflops: 73.09 nanoseconds The bare-metal results are 3x better. Does anybody have any ideas on what may be the source of such latency ? I forward all the exceptions to the guest w/o affecting HV. Only hvpriv is processed, it takes not more than 2 bus cycles. Sorry for poor english _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev