Messages in this thread | | | Date | Tue, 10 Nov 2020 15:55:06 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH 03/24] perf: Add build id data in mmap2 event |
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Em Tue, Nov 10, 2020 at 07:23:34PM +0100, Jiri Olsa escreveu: > On Tue, Nov 10, 2020 at 11:10:46AM +0100, Jiri Olsa wrote: > > On Tue, Nov 10, 2020 at 09:28:51AM +0100, Peter Zijlstra wrote: > > > On Mon, Nov 09, 2020 at 10:53:54PM +0100, Jiri Olsa wrote: > > > > There's new misc bit for mmap2 to signal there's build > > > > id data in it: > > > > > > > > #define PERF_RECORD_MISC_BUILD_ID (1 << 14) > > > > > > PERF_RECORD_MISC_MMAP_BUILD_ID would be consistent with the existing > > > PERF_RECORD_MISC_MMAP_DATA naming.
Agreed.
> > ok
> > > > > > Also, AFAICT there's still a bunch of unused bits in misc. > > > > > > 012 CDEF > > > |||---------|||| > > > > > > Where: > > > 0-2 CPUMODE_MASK > > > > > > C PROC_MAP_PARSE_TIMEOUT > > > D MMAP_DATA / COMM_EXEC / FORK_EXEC / SWITCH_OUT > > > E EXACT_IP / SCHED_OUT_PREEMPT > > > F (reserved) > > > > > > Maybe we should put in a comment to keep track of the hole ? > > > > ook > > how about the change below.. I also switch the build_id with the size, > but I kept the build_id size 20, because I think there's bigger chance > we will use those reserved bytes for something, than that we will need > those extra 3 bytes in build_id array > > struct { > u8 build_id_size; > u8 __reserved_1; > u16 __reserved_2; > u8 build_id[20]; > };
For "maybe we'll use it for something else" doesn't require that it gets before build_id, i.e. to use it for something else it can be as above or
struct { u8 build_id_size; u8 build_id[20]; u8 __reserved_1; u16 __reserved_2; };
that groups build_id size with it, but nah, this is getting funny by now.
My suggestion was not about increasing build_id to 23, just to leave the unused (reserved) bytes after it.
- Arnaldo
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