Re: [RFC] Tracer Ring Buffer splice() vs page cache [was: Re: Perf and ftrace [was Re: PyTimechart]]

Peter Zijlstra
2010-05-18T15:24:48Z

On Tue, 2010-05-18 at 11:16 -0400, Mathieu Desnoyers wrote:
> > Also, suppose it was still in the page-cache and still dirty, a steal()
> > would then punch a hole in the file.
>
> page_cache_pipe_buf_steal starts by doing a wait_on_page_writeback(page); and
> then does a try_to_release_page(page, GFP_KERNEL). Only if that succeeds is the
> action of stealing succeeding.

If you're going to wait for writeback I don't really see the advantage
of stealing over simply allocating a new page.