Re: [PATCH 03/24] perf: Add build id data in mmap2 event

[Jiri Olsa]

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.

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

> 
> Also, perhaps it is time to use F to indicate that @size is in 8 instead
> of 1 ? That would increase our max entry size to 512K, people seem to
> hit his 64K limit (insane as it is).

nice idea, todo updated ;-)

thanks,
jirka