Messages in this thread | | | Subject | Re: [PATCH v6 1/3] trace: Make removal of ring buffer pages atomic | From | Steven Rostedt <> | Date | Wed, 02 May 2012 21:55:18 -0400 |
| |
On Wed, 2012-04-25 at 14:18 -0700, Vaibhav Nagarnaik wrote: > This patch adds the capability to remove pages from a ring buffer > without destroying any existing data in it. > > This is done by removing the pages after the tail page. This makes sure > that first all the empty pages in the ring buffer are removed. If the > head page is one in the list of pages to be removed, then the page after > the removed ones is made the head page. This removes the oldest data > from the ring buffer and keeps the latest data around to be read. > > To do this in a non-racey manner, tracing is stopped for a very short > time while the pages to be removed are identified and unlinked from the > ring buffer. The pages are freed after the tracing is restarted to > minimize the time needed to stop tracing. > > The context in which the pages from the per-cpu ring buffer are removed > runs on the respective CPU. This minimizes the events not traced to only > NMI trace contexts. > > Signed-off-by: Vaibhav Nagarnaik <vnagarnaik@google.com>
Hmm, something in this patch breaks buffers_size_kb and friends.
-- Steve
| |