Messages in this thread | | | Date | Fri, 7 Sep 2012 19:25:05 +0200 | From | Robert Richter <> | Subject | Re: [PATCH] perf, ibs: Check syscall attribute flags |
| |
On 07.09.12 11:11:56, David Ahern wrote: > On 9/7/12 11:07 AM, Robert Richter wrote: > >> Am I reading this right - if exclude_guest is set then perf_ibs_init > >> returns -EINVAL? > > > > Yes, the hardware does not support this. I will look for a solution > > which emulates this is software. > > ugh, that's exactly we need for Intel: if precise is set, exclude_guest > must be set. > > In perf I would like to set exclude_guest if precise is set -- what I > mentioned yesterday for the patch https://lkml.org/lkml/2012/7/20/437. > With my patch -e cycles:p on AMD will then fail EINVAL.
You may set this bit per default. On EINVAL perf falls back and clears the bit. I tested exactly this for ibs and it works.
So, on Intel, if the guest_exclude bit is not set, the kernel simply throws an EINVAL too, but since perf sets it per default with the precise modifier there shouldn't be any problem here.
-Robert
-- Advanced Micro Devices, Inc. Operating System Research Center
| |