On 10/21/2016 11:25 PM, Vince Weaver wrote: > On Fri, 21 Oct 2016, Wang Nan wrote: > >> context_switch : 1, /* context switch data */ >> - >> - __reserved_1 : 37; >> + write_backward : 1, /* Write ring buffer from end to beginning */ >> + __reserved_1 : 36; > > This removes a blank line, not sure if intentional or not. Maybe it would be better to keep it. I don't feel too strongly about this though. >> +.IR "write_backward" " (since Linux 4.6)" > > It didn't committed until Linux 4.7 from what I can tell? Yes, that's my recollection too. > >> +This makes the resuling event use a backward ring-buffer, which > resulting > >> +writes samples from the end of the ring-buffer. >> + >> +It is not allowed to connect events with backward and forward >> +ring-buffer settings together using >> +.B PERF_EVENT_IOC_SET_OUTPUT. >> + >> +Backward ring-buffer is useful when the ring-buffer is overwritable >> +(created by readonly >> +.BR mmap (2) >> +). > > A ring buffer is over-writable when it is mmapped readonly? > Is this a hard requirement? > Can you set the read-backwards bit if not mapped readonly? Wang Nan, could you perhaps clarify this in the next version of the patch? > > Otherwise the documentation seems reasonable. > > Reviewed-by: Vince Weaver <vincent.weaver@xxxxxxxxx> Thanks for reviewing both patches, Vince. Wang Nan, please include the Reviewed-by: in the next patch iteration. Cheers, Michael -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/ -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
