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SubjectRe: [PATCH v2 4/5] trace: Make removal of ring buffer pages atomic
On Mon, Aug 22, 2011 at 8:27 PM, Steven Rostedt <> wrote:
> On Tue, 2011-08-16 at 14:46 -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.
> Could you do the same with this patch, as this one fails to build as
> well. And probably should check patch 5 while your at it.
> -- Steve

I have corrected both the patches. I will make sure that I add
'allyesconfig' and 'allnoconfig' build targets also in my work flow to
avoid such issues.

Vaibhav Nagarnaik

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