Groups | Search | Server Info | Keyboard shortcuts | Login | Register [http] [https] [nntp] [nntps]
Groups > linux.kernel > #1637966
| From | Jiri Olsa <jolsa@redhat.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH v6 2/7] perf/x86/intel: Record branch type |
| Date | 2017-05-09 10:30 +0200 |
| Message-ID | <tF8GR-7BJ-1@gated-at.bofh.it> (permalink) |
| References | <tybJv-4aP-3@gated-at.bofh.it> <tybJv-4aP-19@gated-at.bofh.it> <tzqdr-LO-13@gated-at.bofh.it> <tzAmt-7Jg-13@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
On Mon, Apr 24, 2017 at 08:47:14AM +0800, Jin, Yao wrote:
>
>
> On 4/23/2017 9:55 PM, Jiri Olsa wrote:
> > On Thu, Apr 20, 2017 at 08:07:50PM +0800, Jin Yao wrote:
> >
> > SNIP
> >
> > > +#define X86_BR_TYPE_MAP_MAX 16
> > > +
> > > +static int
> > > +common_branch_type(int type)
> > > +{
> > > + int i, mask;
> > > + const int branch_map[X86_BR_TYPE_MAP_MAX] = {
> > > + PERF_BR_CALL, /* X86_BR_CALL */
> > > + PERF_BR_RET, /* X86_BR_RET */
> > > + PERF_BR_SYSCALL, /* X86_BR_SYSCALL */
> > > + PERF_BR_SYSRET, /* X86_BR_SYSRET */
> > > + PERF_BR_INT, /* X86_BR_INT */
> > > + PERF_BR_IRET, /* X86_BR_IRET */
> > > + PERF_BR_JCC, /* X86_BR_JCC */
> > > + PERF_BR_JMP, /* X86_BR_JMP */
> > > + PERF_BR_IRQ, /* X86_BR_IRQ */
> > > + PERF_BR_IND_CALL, /* X86_BR_IND_CALL */
> > > + PERF_BR_NONE, /* X86_BR_ABORT */
> > > + PERF_BR_NONE, /* X86_BR_IN_TX */
> > > + PERF_BR_NONE, /* X86_BR_NO_TX */
> > > + PERF_BR_CALL, /* X86_BR_ZERO_CALL */
> > > + PERF_BR_NONE, /* X86_BR_CALL_STACK */
> > > + PERF_BR_IND_JMP, /* X86_BR_IND_JMP */
> > > + };
> > > +
> > > + type >>= 2; /* skip X86_BR_USER and X86_BR_KERNEL */
> > > + mask = ~(~0 << 1);
> > is that a fancy way to get 1 into the mask? what do I miss?
you did not comment on this one
> >
> > > +
> > > + for (i = 0; i < X86_BR_TYPE_MAP_MAX; i++) {
> > > + if (type & mask)
> > > + return branch_map[i];
> > I wonder some bit search would be faster in here, but maybe not big deal
> >
> > jirka
>
> I just think the branch_map[] doesn't contain many entries (16 entries
> here), so maybe checking 1 bit one time should be acceptable. I just want to
> keep the code simple.
>
> But if the number of entries is more (e.g. 64), maybe it'd better check 2 or
> 4 bits one time.
ook
jirka
Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread
Re: [PATCH v6 2/7] perf/x86/intel: Record branch type Jiri Olsa <jolsa@redhat.com> - 2017-05-09 10:30 +0200
Re: [PATCH v6 2/7] perf/x86/intel: Record branch type "Jin, Yao" <yao.jin@linux.intel.com> - 2017-05-09 14:00 +0200
Re: [PATCH v6 2/7] perf/x86/intel: Record branch type Jiri Olsa <jolsa@redhat.com> - 2017-05-09 14:40 +0200
Re: [PATCH v6 2/7] perf/x86/intel: Record branch type "Jin, Yao" <yao.jin@linux.intel.com> - 2017-05-10 02:20 +0200
csiph-web