Re: [PATCH v4 09/12] perf record: document parallel data streaming mode

[Andi Kleen]

> +--threads=<spec>::
> +Write collected trace data into several data files using parallel threads.
> +<spec> value can be user defined list of masks. Masks separated by colon
> +define cpus to be monitored by a thread and affinity mask of that thread
> +is separated by slash. For example user specification like the following:
> +<cpus mask 1>/<affinity mask 1>:<cpu mask 2>/<affinity mask 2> specifies

You need to be more clear on the exact syntax of a mask. Ideally
some full examples too.

> +parallel threads layout that consists of two threads with corresponding
> +assigned cpus to be monitored. <spec> value can also be a string meaning
> +predefined parallel threads layout:
> +    cpu    - create new data streaming thread for every monitored cpu
> +    core   - create new thread to monitor cpus grouped by a core
> +    socket - create new thread to monitor cpus grouped by a socket
> +    numa   - create new threed to monitor cpus grouped by a numa domain
> +Predefined layouts can be used on systems with large number of cpus in
> +order not to spawn multiple per-cpu streaming threads but still avoid LOST
> +events in data directory files. Option specified with no or empty value
> +defaults to cpu layout. Masks defined or provided by the option value are
> +filtered through the mask provided by -C option.
>  
> 
>