Messages in this thread | | | Date | Wed, 26 Nov 2008 13:21:07 +0100 | From | Andi Kleen <> | Subject | Re: [patch 23/24] perfmon: kernel documentation |
| |
On Wed, Nov 26, 2008 at 12:43:00AM -0800, eranian@googlemail.com wrote:
I assume you'll be also submitting manpages with the same information?
> + > + A monitoring session is uniquely identified by a file descriptor obtained > + when the session is created. File sharing semantics apply to access the > + session inside a process. A session is never inherited across fork. The file > + descriptor can be used to receive counter overflow notifications or when the > + sampling buffer is full. It is possible to use poll/select on the descriptor > + to wait for notifications from multiple sessions. Similarly, the descriptor > + supports asynchronous notifications via SIGIO.
What happens when the fd is passed between processes using unix sockets fd passing?
> + > + We have released a simple monitoring tool to demonstrate the features of > + the interface. The tool is called pfmon and it comes with a simple helper > + library called libpfm. The library comes with a set of examples to show
I don't think "simple" is the right word to describe pfmon/libpfm @)
> + There maybe other tools available for perfmon.
s/maybe/are/ ?
> + > + To destroy a session, the regular close() system call is used.
...
Some simple syscall examples would be nice. e.g. how to set up a counter that it can be accessed using RDPMC on x86.
> + /sys/kernel/perfmon/arg_mem_max(read-write): > + > + Maximum size of vector arguments expressed in bytes. > + It can be modified but must be at least a page. > + Default: PAGE_SIZE
Is there any good reason ever to enlarge this beyond a page?
If it just depends on future hardware it would make more sense to let a driver patch for that adjust it.
-Andi -- ak@linux.intel.com
| |