Messages in this thread | | | Date | Thu, 6 Apr 2017 18:56:18 +0200 | From | Peter Zijlstra <> | Subject | Re: [PATCH v1 1/5] perf/core: Define the common branch type classification |
| |
On Thu, Apr 06, 2017 at 10:43:19PM +0800, Jin, Yao wrote: > > > On 4/6/2017 5:25 PM, Peter Zijlstra wrote: > > On Thu, Apr 06, 2017 at 04:21:06PM +0800, Jin, Yao wrote: > > > Hi, otherwise we have to maintain 2 branch type copies between kernel and > > > user-space. > > > > > > For example, currently X86_BR_* are defined in lbr.c. To display the branch > > > type in user-space, the user-space has to maintain the same copy for > > > X86_BR_*. I didn't get a better idea. > > I still don't understand what you want; or why it would matter. > > > > Those specific macros are for hardware LBR filter emulation/fixup. What > > does that have to do with any userspace crud? > > I just want to provide a new feature that the user can directly check branch > type > in perf report, instead of looking it up in the binary. Binary could be not > available > later, so it's possible that userspace can't get the branch type. > > The X86_BR are generated when disassembling the branch instruction in > kernel. > They can be considered as the x86 branch types. > > It's easy to let kernel return the x86 branch types to userspace, and then > userspace > shows the branch type in perf report. > > While kernel and userspace have to maintain the X86_BR definitions. One copy > is in > kernel and the other copy is in userspace. To avoid the duplicate > definitions , I define > the common branch type in perf_event.h to share between kernel and > userspace. > That's why I do that.
Argh, fix your mailer. That is unreadable.
/me reflows...
> I just want to provide a new feature that the user can directly check > branch type in perf report, instead of looking it up in the binary. > Binary could be not available later, so it's possible that userspace > can't get the branch type. > > The X86_BR are generated when disassembling the branch instruction in > kernel. They can be considered as the x86 branch types. > > It's easy to let kernel return the x86 branch types to userspace, and > then userspace shows the branch type in perf report. > > While kernel and userspace have to maintain the X86_BR definitions. > One copy is in kernel and the other copy is in userspace. To avoid the > duplicate definitions , I define the common branch type in > perf_event.h to share between kernel and userspace. That's why I do > that.
See, that's so much better..
Oh, so you _ARE_ adding a kernel feature? I understood you only wanted to change perf-report.
WTH didn't you Cc the maintainers?
Also, if you do this, you need to Cc the PowerPC people, since they too implement PERF_SAMPLE_BRANCH_ bits.
| |